Transcripts
1. Trailer Lecture to the Course: Hey guys, It's Samir on behalf of the ps Mobile Packet Data Core. I would love to present this course about PS mobile data core in two G, three G, and four G, to everyone in need of it and to those of you who seek more information in this field. Now this game-changing course in which we'll be talking about the PS4 networks and everything associated with it. If you don't watch this video, I guarantee that you'll be missing out on a lot. As I'll be showing you here some tips and secrets that can change you as a telecom core engineer, either in your work career or even if you're a fresh graduate and you want to be employed in one of the mobile operators. As I know how frustrating it can be not to be employed after finishing university. Or even if you can't get promoted due to lack of core networks information. I do understand that every minute that a core engineer can spare is important. Some here to help you. And in this case, I offer my course non-stop and is available 24, 7 with easy accessibility. Now, let's have a look at the course content. So we have 10 chapters in this course where we will start first with a basic introduction about the packet switching networks, explaining its roles and benefits. Then we'll be hitting the packet-switching network architecture, defining the function of each network node in it. After that, we'll be talking about identifiers in packet networks and what is the role of each of them. Then we will go to the interface chapter detailing each interface packet network. Then we'll be talking about the PDP context, explaining how it is created and how it's him, and it's important characteristics as well. After that, we will explain briefly the EU ISTE management in packet network. And after that, we will start explaining the packet coordinate with contexts. Then we will get to know all the mobility management timers in any packet data network. Then the most important chapter, which is the scenarios chapter, explaining how I u e attaches to a network and how PDP context is created and what is done inside an active session. In the scenarios chapter, we will focus on the signaling messages and the parameters inside each of them. And last but not least, the final chapter, which is the packet switching key features, stating some features in Packet Core network like the FSGS and pull. So this is all the content of our course. What are you waiting for? No. Buckle up your seat belts and let's go through the strike together.
2. Basics of Packet Core Networks & Difference between it with the Circuit Switching: Hi guys, How are you? Today we'll be speaking about the introduction to the PS4. First thing we will explain the difference or evolution of the core network in all mobile generations, whether in 2D or 3D or 4D, and differences between them as well. So in two G network as an example, but core represents the CNS, which is the circuit switching and packet switching core. Meaning if the subscriber is on two G network, which means is attached to a 2D site, which means he is under the two g coverage area. The subscriber will connect to the z-score by MSC. And we'll also connect two ps, which is the back switch important by S. S M is just a node called SGA, etc. Well, the subscriber under the two G network be able to make voice pulse and how he will. You actually do voice calls by CS circuit switching or as we mentioned, the surfaces that are presented by the CS core, our voice calls, SMS and facts. All these are services presented by the SEA score. Score, what is it and once it's use anyway, actually the Peace Corps is so you can make data sessions, which is called the packet switching core. So this subscriber, what we're destroying himself on GSM and the packet switching. So he can make it that assertion, either browsing the Internet or downloading or even sending WhatsApp messages. All of this is by packs which report? What's the difference between m3g? They're actually both the same core. So in 2D it CS and BS, and m3g it CSM ps as well. Now, what's the difference between two G and three G? And let's say the core is constant. The difference will be in the radio or the networks. As we said to G has PSC and the packet control unit. So it can connect on the score to EEG is equivalent to the PSC plus PCU, which is the R and C. So the RNC replaces the PSC and packet control unit. And also in the air interface technique or the technology in the air interface and sending or receiving data. In 2D, we use a combination between FDMA and TDMA. But in 3D, we use only CDMA, which is the code division multiple access, which gives us a higher data rate. So you'll find 3D data rates higher than two g. So this is as far for the 3D and 2D. Okay, So how about Fuji? Fuji is a totally different core, so we removed completely CS MBS. So now 40 subscriber will not connect on a totally new core called EPC, which is the Evolved Packet Core. This EBC is closest to who exactly is closer to the PLS score, which gives the packet switching record. But what's this main function? It makes the subscriber's be able to do data sessions. They can connect to Internet as an example. All right, we'll talk about this a bit more in details and the forging force, okay? So in this case, 40 is four G. In this Fuji, there is no cs. And as I mentioned, the EPC or Evolved Packet Core is similar to the packet switching more. So does anyone know how the voice itself will be done? Meaning, let's say if a forgery subscriber under 40 coverage area and it's connected to a forgery cycle. And this subscriber wants to make Paul, he wants to get out his SFO and megacolon. And he's connected to the EPC, which is the pact, which is packet switching. And the only function of EPC is to help you connect to the packet data network, which may be the Internet. But what are the subscriber walks make a voice call. What will he do? He will do it by something called the IMS. Ims, the solution. But how is it done? Not the solution in vehicles, but where is the IMS exactly? So the IMS is a brand new network. You can say a totally different core network. Is attached or connected by EPC. In other words, you can make a voice over LTE call. Voice over LTE is the IMS. So no one gets just mixed up in these abbreviations if you don't want, of course. So Voice over LTE or faulty is the IMS. Ims is the network name itself or the solution itself, which is the IP multimedia sessions. Plus voltage is voice over LTP. Okay guys, So let's go through another part. Oh, the main function of EPC is to provide or to give you access only PDM, which is the packet data network. Whatever this PDM is or whether it's internet or IMS network. If you want to talk voice over LTE. And as we said, it's equivalent to PS, packet switching war. But the nodes itself are different. So inside the PS4 itself, the two most important nodes are the FSGS, n, and the g, GSM. And how about the EPC? The main nodes or primary nodes are. So you find something like MMAE, which is the mobility management entity. Mme, in very small words, is a node that is in charge of session management. So it's responsible for each session for any user. And it also is responsible for tracking user location. And also it authenticates the user. So let's say there is a user that wants to connect to the Packet Core on the EBC mode will do the authentication. Who will see if you are authorized to access the network? It is the MME. So talking about the 40 Ohm, not two or even three G. I'm talking about the four G, which its core is the EPC, which is the Evolved Packet Core. One of the nodes in the EPC is the gateway. The S-Gateway has multiple functions. And one of these functions is that it takes those data sessions and gives it to the P-Gateway, which is the interface with the packet data network. So if I want to access the Internet, I have to pass the P-Gateway. All right. So what is IMS? It's a vacuum that enamel work. It's a network just like the Internet. So here's an example. Let's say the subscriber can access the Internet. He accessed through the EPC. So the EVC is connected with the Internet network. The EPC is also connected to another network called the IMS network. And view the IMS network. He can make Voice over LTE normally. In that case, the subscriber will stay on the 40 coverage. Here. We'll do this voice call and we'll stay on forging. There's also another solution of course, we can go to before we go to the IMS. The network provider itself sends or gets four G and gets EPC and builds many Fuji sides. So before we think about IMS behalf to come up with another solution so that the poor geez subscriber can do voice calls. What can they do, or what other solutions might be, have. The CS fall back or circuit switching fallback, which means that this 40 subscriber decided to make a call. So automatically what happens? He will go down to see a spore back. He will jump to 2D or 3D numbers. And in this case, he will use the CS core network so he can make his call. What if he's receiving a call, he will drop to two or three G. And will you make his call on the CS core network? So what does this mean exactly? This means that if the subscriber, or in other words, if you are a subscriber, you'll find a lot of your, Let's say yourselves experiencing the situation as before G or IMS. And certain countries is not actually that why the spreader or not all the providers did the provisioning to all subscribers. Alright? An example of a provider, we are forced matching. Amy has, say an example has 20 million subscribers. This means that this company get provisioning to only 10 million, maybe even less. So there are a lot of people left that actually hadn't been provisioned on the IMS network. What does provisioning mean anyway? It means I think these people and configure them on the IMS step so that this person is under the Fuji coverage area. He will actually do a call through the faulty or IMS. What if I didn't provision them? They will go to CSF far back. So when he makes a call, he will go through CSF fallback. I'm Rob to make the call on two G and three G. So for the amount of loss that will actually read on his mobile for G, but when he makes the call, you're finding is mobile cognitive to geo-region and buy. And of course, Let's go. If you have a problem and are bolted provision. If you're provisioned on the IMS and you can make Voice over LTE. But there's a problem in the IMS, whatever this problem may be, and anything in the beginning or in the beginning of any integration of any new service has to have a lot of problems. So we can understand it clearly. So we can actually saturated. And the situation and the problems start decreasing dramatically. As we said in the beginning, there will always be many problems. So if you have a problem in the voice over LTE or IMS network, then what automatic doesn't disconnect the call and it tells you the call actually failed. No. But actually, the network automatically takes the other solution, which is the CS, fall back on biopsy to 2D or 3D networks. So you can do your voice box. So now we actually thought about record network evolution in different mobile generations in two G, three G, and G as well. Okay, so let's go to another place. Let's take a quick review on the CS core notes. All right, as we said, is yes, on the circuits, which that is the core in two G and three G, the score is responsible for the voice calls or SMS or facts. So if you want to make a voice call or send an SMS or facts, it's done by the CS4 or circuit switching word. Cs4 also gives us a guarantee that we can connect on other networks. In other words, let's say you want to connect to another provider or another provider quarter. This has core of the other provider. So let's say you have a provider and want to connect to an external provider. In case you have a subscriber that wants to call another subscriber. This is done by circuit switching or by the MSC. The key player in CS core networks is the MSC. This is the most important node in CS. Cs also provides the user plan and control plan. If you remember the difference between user plane and control-plane, the control plan. So let's go over this part again. The control plan signals, messages, flows, NDCS core network or control plan actually does the signaling of the message itself. But how about the user plan? This is the traffic where speech, which is also supported by the SEA score. Alright? Who's responsible to the user, this user plan or the traffic indices score. It's the media gateway, which is responsible for traffic or speech traveling through the circuit switching war. So as we said, the circuit switching has something like a split architecture. And the split is that the MSC was caught and deployed into two things, which are, which are the MSC server and the media gateway. And we mentioned that this is a C has two functions, control signaling messages, and also get the speech traffic. How about the split? Architecturally divided them, as we mentioned before, into two things, the MSC server and the mitigate way. So the MSC server is responsible for the signaling and the media gateway is responsible for the traffic. And at the same time, the media gateway is also responsible for the connection with any external network. So if I want to send my speech traffic from one provider to another, I need to be connected on both media gateways. The most important node in the circuit switching is the NSC server, which is responsible for switching and routing the users. So the connection is responsible if a person wants to talk to another person. So the MSC is actually responsible for connecting these two people. It initiates the connection with them so they can actually call each other. You can also do non-service related tasks, more related to cause, such as maybe authenticating the subscriber. In other words, not any. One can connect to the ECS coordinate work, either attach or even register to the MSC, which is inside VCS or network. It's also responsible for some non-circular related matters. And as I do the core itself, as authentication process, as it provides the authentication parameters from the AUC to the MSC and also has a role in the location update. Its role is to know the subscriber is registered under which MSC. And in the same time, it gives the NSC all the information and profile of the subscriber. We have another node called the gateway. The gateway MSC is what we said in the CS course, is not a stand-alone. I didn't just bring a node and call that a gateway. I want to go through a network and, or call maybe anyone in an external member to go through gateway MSC. Begin we MSC in an eternal function available in the MSE server. As an example, if I give ten MSE servers, if I select four or five of them, and I'll put a gate, we function because if any subscriber, I have wants to call another such fiber from another network that will appear through his Gateway or through this gateway. So the gateway MSC is a good way to external networks. So I can connect to external networks. It has to be through gateway MSC. Again, we function which is available in some MSE service. So we can be more precise. Okay? So what happens? The MSC must authenticate the subscriber and see if he's authorized to access this network or not. And also provides a location of or if the subscriber moved from one location or area to another location or area, who confirms this task? It's the MSC server. And at the same time, the MSC server contains a small database server called the VLR, which is a or the visitor location register. Vlr function is to store the subscriber data to any subscriber attached under this MSC. So me as an MSC, any subscriber below me and registered with me, I will be responsible to store all subscriber information under the VLR. Another node that is important in the SEA score is the HLR, which is the home location register. As we said, the MSC server contains a VLR, which is a small database for all the subscribers available in the MSC. What about the HLR? This is a huge database for all the subscribers that are in my network. Any subscriber attached or connected to the CS court will be done by the HLR. So it's profiling information is stored on the HLR. So it's a centralized database that have all the subscriber data in the network. Hlr also gives through some signaling procedures which are circuit waited. An example is like looking forever be number on the MSC of an a number. It sends the HLR and asks where this person is at. I want to talk to him. Where is he exactly on which MSC? So HLR tells him he's on this MSC. And we mentioned how on the CS core course. Then I have the EIR, which is the equipment identity registered in AR is a database for all the handsets in my network. So anyone who registered under the MSC or under my network, I think the MEE, which is the identifier of the handset or the Mobile itself and registered with the EIR to check with the EIR If it is waitlisted or blacklisted, I had to do I have to actually check if this mobile equipment is polar or not. And based on this check, I will allow this person to access my network or not. This mobile may be sold him, so he won't be able to ask my network. This happens through the EIR. Then I have the SMS center. This is responsible for sending and receiving the SMS and also give some functions as identifying the text format. It takes the text format you send and thus the identification process and has a banding function. So if there is a problem in the network, or maybe the resources. As an example, the network has low resources. I won't be able to channel this message to be sent to the other subscriber. As I have a limitation in the resource itself. So the SMS Center has a function called bagging function. Its role is to store the SMS until there's a bacon resource or channel that I can send this message through. As we mentioned before, we give the priority to the voice box. So if I have a limitation in channels, I give priority to voice pulse to happen first to the channels are available. Again, this high utilization that happens decreases a bit. Then I start sending these messages. Or till I send these messages, they are actually stored in the SMS seminar. Another node called the F and art, which has the flexible number registered. As we said in some operators, they have a solution called MMP, which is the mobile number portability. What is the function of MMP or the F and R? Its function as a subscriber. For example, if you have a specific number attached with a certain provider and you want to change it to another provider. And you don't want to lose this specific number that all your friends know. So why the FINRA, you can move to another provider with the same number. So FMR or NNP gives us the capability to let this subscriber, or let the subscriber go to multiple buyer within the same number. And this scene number will also be owned by the other providers as well. Now the last thing is that the AUC or the authentication center. This is used to generate the authentication parameters so it can affect authenticate its subscribers. In other words, it generates authentication parameters to see if this subscriber, once registered or attach under this network, Is he authorized to access that work or not? So this was just a quick brief about the CS core network. Alright, so now we're done with this part. Let's go to a very small comparison here. I just wanted to show you. Alright. This is more comparison between circuit switching and packet switching network. We're just going to state the difference between them. Of course, the CSF core network, it's most important and main function is the voice calls. As it enables the subscribers to make voice calls so they can talk to each other. The packet switching network. What's its main function? It lets us subscribers duty data sessions as browsing or Internet downloading to specific data chatting. As an example of this is by packet-switched court. If of course you're opening a data set. So the main function of a CS is voice call and the BS is datasets. There are some features or aspects for each technology or each core network. As an example, the channel assignment in the SSS circuit switching core network. How does it look like? In the circuit switching core? I give a channel, so only one user. So I give this subscriber a channel to make his call or his trophic call on. And once he's done with the score, I let this channel Bible again. So I can let another subscriber or another to subscribers that want to use the channel be available. How about the ps? Packet-switching? Know, I can't give more than one channel, so more than one user. But this can cause motivate. But in packet switching, delay is more acceptable than voice. As an example, invoice, you can't do a call and your voice is, see just saying, how are you George, the other person only heard how are you And his name George. A period after two seconds. So the lay invoice is unacceptable. But in the packet, you can browse or download, a small delay may happen. And you won't even feel, how about the data transmission and the CS? I send the data in one pass so I don't divide it, or I take this link and send it and send the data itself through it and comes another link to send other data on it as well. No, it's just one link. I send that out. That's it. Okay. How about packet switching? I can send data through more than one bank. How does this happen? You send the data through multiple links. You'd have all your packets, then you send a few through each. And in the end, you put a router that collects all this data. But it's organized of course. And this gives more delay in packet reaching network. But I send all my data one time in one pass. But in the packet switching, I sent it through multiple passes on multiple links, and then I collect them. So it gives me more delay. But as we mentioned, the packet core or PS, the laser bit acceptable more than the CNS. But in voice calls, it's not even acceptable to even have a delay. Okay, So due to sending the data or my traffic on one channel, or take, I would say I take this one channel or one user in one pass. So here I have fixed bid rate. The bit rate doesn't change, but I send in the packet switching in more than one pass. So the bit rate may decrease or increase because I don't actually own this channel. So the delay may occur. This multiple passes may also have problem or anything that may happen to them. So I have a variable bit rate. Even if you are downloading, you won't find your bit rate stable. It may give you one mega, sometimes, maybe even 100 kilobytes. It keeps increasing and decreasing. There is a variable. Among the voice. You speak on a steep of bigger. The charging in CS or circuit switching. You got charged per time. How many minutes you're actually consuming when the packet switching, it's per volume. So how much did you download, how many megabytes did you actually use? Cs delay is less than P S. And we said this is accepted and this is not. How about the CS core? Access them of water connected to the same axis backwards, which are the 2D and 3D snaps. Unlike the EPC, which is the Evolved Packet Core and forge, it does not work on 2D or 3D only on Fuji. Alright? Now, the last thing for the core networks, the CS is the same for two G and three, G and P. S is also the same for 2D and 3D. So this is just a quick review on the Pietro. Thank you so much for your time, guys.
3. Packet Switching Network Architecture Part:1: Let's now talk about the ps, the packet-switching network. As we said. What is packet switching? It is the technology that allows data transfers between users in cellular networks with central external networks. An example is a user in my network who wants to do that, associates, who wants to make browsing, downloading, or even chatting. It will be done by the Packet Core network inside the mobile operator and by an external network as the Internet. What is the most important function for the packet-switching worked? It is the data transfer, which is you being able to transfer your data from the user to the internet, or vice versa, from the Internet to the user. As an example. What are the benefits of packet-switching coordinate work? Dps gives me a higher data rate compared to see us as the CNS is a fixed bit rate around 9.6 kilobits per second. And packet switching starts from 56 kilobit per second. And it depends if you are two or three or even 3.5 G. All these rates are different. In Packet Core, resources are reserved once needed. Unlike the CS, I'll leave the resource or channel to the user. Unbelief finishes what he's doing. Fun the packet, the user might be doing a data session, but he sat there for a small while. So I took a bit of a resource and once he's back again, I give him those same resource again. And in this small while, what I can do, what can't, what actually can I do? I can give it to another user. As we said, delay may happen. This packet connection setup time is lost and packet-switching compared to CS, which is circuits which, which means if I want to do a data session, it would be faster than doing a voice call. Of course, the packet switching or P S corps has higher flexibility to do more services on. I can design anything I want. Now, let's talk a bit about the packet switching core architecture. What are the network nodes available and what are its functions? You will find in the Peace Corps, the most important node is the SG SN, and it's an abbreviation for serving GPRS support node. The most important function of the GSM is the routing of packets or data to or from a mobile station. So it's responsible to take these packets from a mobile station and deliver it to PDF, which is the packet data network, like the Internet for example. And in the same time, take the packets from the PDN or packet data network, internet and send it to the user or mobile station. So this is the main function of as GSM. It is also an entry point to the core network, exactly like the MSC. So let's say the MSC is the important or the key note in the CS4 network. So the FSGS N is the most important in the packet switching or network. It's an entry point. So if anyone wants to register or connected to the packet switching court, the Connect by the S GSM. It is responsible for the registration of any user. Any user who wants to connect the packet core. The registered themselves first on the SGA asset. And it is also responsible of tracking user location. So any user that does routing Area Update and just moves from a routing area to another routing area. He registers the last routing area he was into the GSM. And why does he do that? It's actually because of the GASGAS n has a data session, the Internet or packets from the internet and going through the user. So it can find where this user is. It must have the location or routing area where the user was present. So it tracks this user by the routing Area Update. And it also is responsible for the authentication of a subscriber or the user authentication. So if a subscriber wants to attach or register a packet switching network, he has to have authentication. The SG ISN must see if he is authorized to access this network or not. It works as a tunneling or makes IP packets, which is tunneling, which means it takes the packets from the 2-AG subscriber. Even if the subscriber is on 2D or 3D network. It takes those packets and makes a tunneling process through the G, G, S, N, which has a role in the interface with the packet data network. When I say PDN, always know that I'm talking about the Internet or the IP network or the Internet Protocol network. So the FSGS and does tunneling to those packets. As gs n is also used for two things. As the old MSC, as in the legacy architecture, as we said, that the MSC is used in signaling and user plan as it handled signaling messages. And in the same time, traffic or speech trap. It's also responsible for the mobility management. As we said, the routine are an update and registration office is called mobility management. So let me rephrase that again. It's also responsible for mobility management. And as we said, the routine of any update and registration is called the mobility management. The SG SN is also responsible for storing subscriber profiles which are registered or attached on it. As JSON also does offline charging as the MSC as well. And as the MSC generates CDRs to the subscribers phone calls as gs and generate CDRs for the data sessions of the postpaid subscribers. So if there is a postpaid subscriber, a person who has a bill and is doing a data session. So who generates the CDRs and count these? It is the GSM, which is the main node for the packet core switching network. Okay? The second most important core is the GG ASN, which is the gateway GPRS support node. As we said, the GG SN is the interface with any external network. Any external network connected to the packet switching or by the GI, GSM. So if I want to connect to the Internet, I guess I go to get or I get my gigi S N on this packet data network. Also is used in the pockets tunneling from the SG ASN to the packet data network. So the packets come from the user to the USGS, and then G, G, S, M, Then Gigi SN gives these packets or traffic to the Internet or packet data network. The DDGS n hosts all external network APIs. So does anyone know what an APN or access point names? All right. Let's pick more about it. The GGE SN has more than one APN. Each APN is linked to a specific PDM. So any external network, the score is actually linked through it and has an EPM stored in the GSM. So the GGE SN, I can find an APM or an IMS APN. And I can also find a corporate API. So each external network has an APM. So the APN is a logical name for each PDN or packet data network. As we mentioned, this PDM can be internet or IMS, or a corporate network for a company or bank. Pdm can be any of these, but most commonly used is the Internet. Of these external networks or PDMs have APN stored in the GG as n. Okay? So what's inside this APN? Apn has a pool of IP addresses. But what is the role of this IP address? Now, this subscriber once access the Internet or data session with the Internet. So what does he do? First, he registers himself or asks for an attached request on GSM. Second thing, he opens a PDB context, which is like a connection between him and the GSM and use your equipment. So it's like a full pass, which helps move the traffic from the user to the external network and from the user to the external network. So this is called the PDM or a PAD. A PDM contexts. Along with the user attaching on the Packet Core, he sends an attached requests stating that he wants to connect to the internet or he wants to have data sessions with the internet, which is available on the attached us. So here's what happens. The ISG SN goes to talk to the GSI and asks a to give it an empty IB from its IV pole. So this person can connect to the internet. So the SDS and a locates the IP address for this user from the Internet APN. So the subscriber can connect to the Internet. Let's give a small example here. Let's say that this is the Internet API in the GSM. And here is a corporate APM, and this is the third API, whatever it is they may be. So here I can tell that the Internet APN, the second is the IMS APN. And the third example, or for example, is the corporate network API. Inside this Internet, APN is a pool of IP addresses. Let's give an example of 1.1.1.11.1.1.21.1.21.3. And I can go further as an example till 3.3.3.3. And a user. And actually a user came one thing about a session with the Internet. So what happens? This user, as we mentioned, attaches on the as JSON, and in the same time when he sends the attached request, he says that we want to connect on the internet APM. So what does this as you send do? It advocates one of the IP addresses in the pool located in the Internet, APM. And let's say the SDS and decided to send to the GGE SN and VGG SN decided to give the IP address of 1.1.1.3 to the subscriber. So this is the subscriber. The soda subscriber will access the Internet using the IP of 1.1.1.3. Here, each external network has a specific PDN found in the GI GSM. So as we said, the internet has an intranet APN, hosted in the GI GSM. And the IMS has an IMS APN hosted in the GDS n. And the corporate network also has an APN hosted in the GG. This corporate can be a bank, for example, like how the ATMs you see on the streets are connected to the main network of the bank by APMs. They have like a, let's say a SIM card which takes an IP address so it can access the network of the main banks. All right? Okay. So let's talk a bit about like the other part, which is the network architecture. So let's talk about the roaming architecture inside the packet switching h4 on the high level. And we'll be talking about it of course in more details later in this course. But here we're talking about the network nodes and what scenarios that may happen on a high level. And everything will be discussed in details upfront. Alright? Roaming. For those who don't know what roaming is, it means that the user travels outside the coverage area of his network. For example, your subscriber for a network provider and you decided to travel. And you have the SIM card for this network provider. So you're outside the coverage area of this provider. The most important part about roaming is that you understand the difference between HPL and VP element. This is your network, the edge PLMN is your network and your coverage area. And it actually is, let's say, let's say you decided to travel to the UK. And there you will connect to a network that has an agreement with your provider. So this is, this other network will be your VP lm n, which is your visiting PLMN area. Both HPL and n and n are both mobile operators or networks. So the same notes are available. So here you connect to the as JSON, HLR, and G, G, S, M. And in the end, you connect on a packet data network. And here you will connect on the same as well. Here roaming means moving from HP to VPL m, n. So me is a core engineer. What are the types of brokers that I have? There is an Alba Romer and there's an inbound Romer. The album Romer, are the people that room outside my network, but there's still my subscribers. The inbound rumor is a subscriber from another network that registered or attach themselves through my network. Yet the point, okay. So I'm actually talking, talking from a view of a core engineer before we can continue in this part, the data sessions so we can subscribe to a data section what happens? As I said, he attached to a network, he attaches to the GSM. And they have a scenario. And we're going to mention it. But lots, we have lots to talk about on a high level. Now, after the subscriber attached, he opens the PDB contexts, which is a link between as GSM and G, G, S, N, and the RNC. Until it reaches the user. This full path is called BDB context. And this is how I transfer my packets from the subscriber till the Internet. So the normal scenario for packet travelling from user to the internet, or the internet to the user is from the UE to site two, RNC, USGS n to GG, SN till the packet data network or Internet. But what if the user will receive it will be, let's say, what if the user will receive? It will be the other way around. From the PDN to the GGE, SN 2, the SGA, SN 2, the RNC to the site, and then to the user equipment that's in case if it receives. So that's always my normal scenario. In case of roaming, what happens? How does my scenario go? In case of outbound roaming? One of my people want roaming. One of my people want roaming. So let me give you a clear example. What do people want to Rome on another network? But he's still with me. He wants to make a data session. And this person traveled and connected to the other network. The user will first connect on the site, whether it's two or three G, which is in the country and from the site to RNC to serve B and C. So I'm sorry, refers again as to the RNC, to the FSGS n. But the FSGS n here does a bit of a different thing by something called the DNS in which this as JSON, as this user is or belongs to the specific network by a node called DNS. So it will send his requests by the GSM and the g, gs, and we'll give it to pack data network, which is the internet. Okay? Now we're talking about the network architecture. So for this person to do a data session, his boss goes from the RNC to the GSM. But this as JSON will not go to It's Gigi SM, But we'll go to the DSN of his country, of the HPL. And by that, I can go to the packet data network. And what if an inbound Romer, same exact scenario, but vice versa. So he's not in my network, but from another network and came to register on my network. So you can make a data session. The user will send data or is traffic to this pass. So he will go to my S GSM and his GG ESA of his network that owns this subscriber. And from the CGS n, I will go to the packet data network, which is the internet. So this is the high level scenario and roaming. Thank you so much for your time guys.
4. Packet Switching Network Architecture Part:2: Hi guys. The last time we talked about the architecture of the packs, which encoder network. We said that the most important node in the score is the S GSM. And the SDS n is the serving GPRS support node. And the main function of D as GSM or packet switching or network, is to give you access to the external networks as the internet, for example. And one of the important functions of DES GSM is routing. The packets are data from or to the user. So it takes the packets from the UE, delivers it to the Internet or the external network, or takes the packet is coming from the Internet and to the user. As JSON plays two roles, it works in control plan and also the user time, which means it handles signaling messages and routing and goes through the packets, are trapped as it takes the packets and delivers bit from place to place, from user to SG, ASN, or GSM. And it also controls signaling messages. We also said that the GSM is like the MSC in the circuit switching as the MSE in circuit switching is the key node, as in packet switching, the GSM is the keynote. If also, it also actually authenticates if the subscriber is allowed to access this network or not. And in the same time in webs and the mobility management in which stores the user location and knows where the users below it in which routing area. Because if there are downlink packets coming from this user, from the internet, the GSM will know where this user is, so it comes forward with the packets. It also works in the offline charging as it creates CDRs from the users. And Benny charges there. As it takes all the detailed records and actually sees how much usage this username, the start imposing like a bill for this user. And will of course know how this is done upfront in the course. So at a high level, this is the main as JSON function. All right. The second keynote is the GSM, which is an abbreviation for the gateway GPRS support. No. It is the interface of the external network. So if I want to access the Internet, I have to pass the GSM. So before I go through any external network, I have to pass through the GDS. And for us. It also worked in packet tunneling. As it tunnels the packet coming from the SG SN and delivers it to the packet data network as an example. And it also works as all sorts vice versa, as it tunnels the packet from the packet data network, which the Internet and delivers it to the user. Third function is that it actually host the APMs, which is an abbreviation for Access Point Name. As we mentioned, that the APN is a logical name for any external network. So let's say I have an external network called the Internet. So automatically I'll have MIG, GSM, an APM for the Internet. And its function as if there is a user that wants to access the internet. This user attaches to a Packet Core or my packet switching, or normally, and after it he attaches, he takes an IP from the Internet, APM. In this GSM. And with this IP, you can access the Internet. So GSM hosts API, which is Access Point Name, and this APN is the logical name for any external network which has a bunch of IPs in it. And any user who wants to access the Internet takes an IP, and then he can access the Internet for browsing and babble. All right. Then we talked about architecture in robbing. And if this usually is roaming, whether he is inbound or outbound, what will happen exactly? Of course, without roaming. Let me just get back to this one. Of course, without roaming. We said if a user wants to make that assertion, first thing he registers on the packet core as he sends and attach request and attaches himself or the only GASGAS sensory. And after he registers what happens. These are all procedures that will be, of course. So like registration, authentication, VDB context, and a lot of things happen. We'll talk about all this. But at a high level, as we said, the user attaches to the network or the packet core network, specifically on the GSM. And what happens after the attachment. This user wants to access the Internet or wants to send traffic or packets through the Internet as he wants to browse, download or whatever, he wants to know how we finished the attachment part. Now as you finish the attachment point, so now he wants to prepare how to send his data or packets. So he has to open BDB contexts. And consider this context a tunnel that opens between the nodes themselves. So we can transfer the packets of data till it reaches the internet or comes to us from the internet. So consider this BDB context, a tunnel that opens from UE to SDS N, two G GSM. So I can transmit a packet that are coming from or to the user. So the second, Let's say the second part after detachment is the BDB contexts. So this is a normal scenario for any user who wants to make a data session or wants to send packets. Okay? What if this user is running? What, what is roaming anyway, let's recap that party guy. It is when the user leaves his network and travels and it's attached to this external network. But originally, he's still belongs to the network of his country. And as according to near, in this case, this user to me is called an outbound rower. What if a user team from a country and his network is not owned in my country and attached or registered under one of my networks. As he's coming from. Just like you see a short time or Greek time and just leaving up to them. So this person, to me, as an engineer is called an inbound Romer. Okay? In this case of inbound or outbound Romer, I like it all is the same scenario. Nothing changes here. As an example of an outbound user who left his network and traveled. So he found himself attached to that other network. As there are, let's see, there's an agreement between providers so they can facilitate people to access Internet as an example, but with maybe a higher cost depending on the provider, women. So this person, audience person scenario is that he must say census packets on the side of the country. He's actually is she in there? Rnc then goes to the GSM and the SES and we'll look at this person's requests from the APN of his country. This FSGS n will forward to the gigi S N and from the GCS and he can go to the packet data network. Okay. Let's talk a bit about the Dina's, which is the domain name server. This is a node in the packet core network. Sometimes it works on boys. But now we will know its function. To be honest. The function of DNS is that there comes a request from a node like the USGS. And DNS response to this request that you send or you have to go to a certain place. It asked like something you can ask directions from. So the nodes go to the DNS by domain name, and then DNS translates this domain name to IP. And this IP is the IP of the node that you're supposed to go to, or the destination node that is actually supposed to reach. So for example, here, I have a specific APM, the domain name of this API. And for example, is, let's say the Internet dot d slash or dash mobile. Butyrate is the APN, but the T dash mobile is actually the operator. Okay? So this means if I want to access the Internet, APN buy T-Mobile, which is the operator. You just explain that further. Now. The SDS and we'll go with the domain name of the Internet.org slash dot-dot slash mobile to the VNS. And Dina's wave to the GSM, which has the Internet ABN. So that will take this domain name and translate it to the IP address of the gigi S N, the TTS n where the bomb experiment, I'm sorry, but we're just prisoner gap. So the domain name and translate it to the IP address of the gigi S N, which has the Internet, APM. Apm. We have two types of DNS, which are the Internet and the external DNS. Internal DNS or an external DNS. All right, so the first thing is the internal DNS or the ideas. Before we explain, we must understand that in any mobile network, the operator or modern network operator, I don't have just one GSM know. I have 12345, multiple multiple judicial actually. They're all codes on her notes of APMs available in the GG SMS. I can put the Internet APN in this GSA and the IMS APN in this GSM and corporate, Let's say APM and the 30 GSM. So that means that not all TGS and carry all the APMs. And all the APMs are available in all GG SMS. So it may be available here and there, but not available in the second scenario is that you attach to the network and then ask BDB contacts. See you can send data or packets would be Internet, for example. When you create this BDB contexts in the request creation that you, do, you actually sent to the APM. You want to connect it. That's the whole point. So does this FSGS and nowhere the APN is? Actually no, it doesn't it doesn't know what the EPA is on which GSM, whether GG, SN1 or two or three. So who knows? It actually goes to the internal DNS. So this SGX, and we'll take this requested APM as this APM comes in a domain name as the Internet dot T dash mobile. And then the SG ASN takes this domain name to internal DNS and asks him that this person wants to connect to this API and take an IP from it so we can access it. So please tell me where, where the Epinions tell me the JSON that has the address. So the Ethernet dealers will actually respond with IP address of the CGS L, which is for example, 1.1.1.1. So now the as GSM will know the order of this IBMs and we'll ask to share connection with the Internet APN that you have. So now Dina's let the S GSM nowhere to go. Whereas the user or APN, which this user should connect on so he can access the internet. Okay? So now let's go through the DNS for it, okay. For the external DNS is used only during growing. I don't use it in my network. In my country. I only use it while roaming. How? During roaming, the user is connected to this as GSM. So let's give an example. Let's say user came from one country to another and now attach himself in that work of the other country you traveled. So now is attached to the SDS n of this country. And now this user is attached and we open our VDB contexts. So some packets with Internet, for example, as GSM. In the BDB contexts creation request, we'll be getting into mainly the API and domain. We said, how does the APM domain name look like? Let's say this is a man from England and now he wants to open ability contexts. So we will send an APM that looks like this. Internet dot vf UK. So this is domain name that comes to the FSGS. N will take as the main name and send it to the internal leanness. But the utility less will not understand what it is. What is Vf UK more Vodafone UK. Please bear in mind that this man is with Vodafone UK and isn't another country that also has Vodafone. He will send the B2B context that he wants with the domain name for the Internet will see Internet dot Vodafone UK. Which means he wants to access the Internet APM by Vodafone UK network. The CSM will not understand this domain name and doesn't know to which GPS and should it go through and doesn't know how to open the BDB contexts with which GSM. So it will send an IDMS, but ins will not understand what domain name is committed. What is Vodafone UK? As other domains I have is Vodaphone dot country. Let's say I'm in for example. For example, just let's say for the of IDMS by itself, not understanding, it starts to send the external DNS. It tells the external DNS that this domain name came. And I don't understand what is the external DNS has a connection with the G or X. Now, what is the GRS? It is international DNS. And now let's go through its function. For starters, direct is an international mode not specified to one operator for countries all over the world. So its function is to understand any available domain. But you knows that this domain is from the GSM, which is the SE for number X. In which this is like. It is actually in Vodafone, UK, which has an IP of 1.1.1.1. So the director will respond to the external DNS of 1.1.1.1. Then the external DNS will move it to IVANS and then to the GSM. And now the SUS and knows that it should send this to the GSM, which belongs to Vodafone UK. So now when the user said BDB context requests took an IP address from the API and address on his GSM in Vodafone, UK. By the external DNS and the GI tract, which is the international DNS. So the T-Rex has access to all the DNS all over the world. So it now, or let's say that the IP address of the DSM that the user was supposed to go to was 1.1.1.1 for an example. Alright. Alright. So from here, it's sending GS, GSM and asked him to open a B2B context with the GDS n of Vodafone, UK. And it gives him at IP and gives it to this person so he can access the internet with it. The DTS and this person's name or home network is responsible to assign or allocate this IP. So the node or the node after the DNS, which is the PCRF, which is an abbreviation for Policy and Charging Rules Function. What is the function of a PCRF? If function, it's actually, its function is to send to the GSM and asking what are the PCC rules that we need to apply on the subscriber. So let's say this subscriber wants to access Facebook, Instagram, WhatsApp, how will this person be charged? So let's say Facebook. How much will one mega cost? Or what's the speed he can actually have during Facebook browser? Or let's say he went to download. Can I do something called throttling? Probing actually means that I can speed to have orthogonal blocking specific traffic. Like in some countries where Whatsapp calls can be cutoff. So those are PCC rules applied on all subscribers. So PCRF function is to actually ask the GSM some pieces he rose to be applied on the subscribers and in the same time give it the quality of service that should be given to the subscriber. So it says priorities, for example, of who opens BDB contact contexts. And this is set by the quality of service. And who assigns this quality of service is actually a PCRF. Pcrf can actually lead me, rephrase that, which you can assign rules. As we mentioned, the PCC, maybe some small rules like traveling or blocking traffic or quality of traffic on a specific application. So example of blocking the WhatsApp voice is a PECC role or throwing the traffic of downloading a subscriber. That's the second rule. Or I can make WhatsApp chatting for free of charge. Thus they see a third piece is 0. So all these three together, the blocking, the free of charge, the throttling of traffic. These three combined, I call the RBM, which is the rule base name. Which are a bunch of PCC rules which should be applied on the subscriber. Okay. Now, let's understand more about the PCC rows. So visceral is charging only serviced Dataflow with different charging rates. So the provider can give you free Facebook all month, but when you start browsing, it actually cost you. So all these are PCC rows. When this person downloads. You can actually use this. We can actually use the throbbing to decrease traffic or betrayed to 50 percent. So he doesn't use a lot of Internet or this is why I say, as mentioned, we use the troubling part. So these are all ways that I can apply. And I can block a specific traffic stream as what's a voice, as it may be something political. And now the mobile operators are actually competing to give different charging rates to the subscribers. So they will come to you with an offer as you can go to WhatsApp or Facebook for free for one month if you subscribe in this specific, let's say package with so let's what is the type of charging or the type of charging is actually called based charging. Or the type of charging is called flow-based charging. How does this happen? As we said, the PCRF will instruct the GDS and to apply some PCC rules on the database. For example, it can ask it to put WhatsApp traffic on grading group number 10 is defined on GDS and then the waiting room number 10, or any traffic attached to this group is free of charge. And at the same time, it can ask for the traffic of Twitter and Telegram to be on reading group number 20. So we can, for example, throttle bit rate, the bit rate or traffic rate to 50 percent. And for example, we put Skype traffic on blocking. We put it on when group number 100. So this traffic or any service on this group number 100 will be identified by the DDGS, n would actually be blocked. So what does the rule base name C, for example? Mark WhatsApp on reading group number 10. So this person can use WhatsApp chat free of charge, Twitter and Telegram on re-group number 20. So that may mean one megabyte on them will cost half price, for example, or other traffic with reading group number 50. So if you browse anything, any megabyte will cause a specific fee. And also when you download, it will cost or asked to throttle your bit rate to, let's say 64 bits per second for example. And if you are making Skype costs, it will actually loved these costs. Now, let me explain this part. We're going to another node called the DPI, which is an abbreviation for deep packet inspection. We said that the PCRF sends to the GSM PCC rules that should be applied on specific traffic laws. For example, applied PCC rules on Facebook or Twitter, or Instagram, or downloading, or even browsing. All these are traffic streets. Now, how will the GDS and apply the PCC rules if it can identify what the traffic stream is. The GCS n has to know how to identify these kind of traffic. So it can know which pieces you rule to apply on this traffic. So it's a strophic, Facebook or Twitter or Instagram, or didn't know grabs in for example. So it can actually know which species rule to apply it. To enhance the capability of this GSM, we entered a new node called the DPI, which is a deep packet inspection. What is the DPI and function? The DPI Presley is a separate node. So some operators can get this DPI as a standalone node for a solution. Or some operators, can they get this DPI, an internal or something inside of the DSM? Now, the function is that any data service pole coming through the GDS and the duties and asks the DPI, what is the type of this traffic? So it's Facebook for example. There are applied the PCC who aren't. It's a free of charge or not. So that's all what the DPI actually does. So now we're actually finished with the part about the notes in the packet switching network. Thank you so much for listening guys, and hope you understood everything from Iran.
5. Identifiers in PS Network: Hi guys. Today we're going to go through a new chapter, which is the identifiers in the packet core or packet reaching core networks. All right. First thing we'll talk about is the location identifier's. So we have the PLMN, location area identifier, routing area identifier, CGI, and service area identifier. Okay. First thing is the PLMN, which is the abbreviation for public land mobile network, which is my network. So all the coverage area of a provider in a country is called the PLMN. So the PLM and consists of two things, which is the Mobile Country Code and the Mobile Network Code. The Mobile Country Code is stable in all the operators. But the one who differs is the mobile network as each provider has its own network. Second thing we're going to talk about. So the second thing is the location area. Here. I can identify that I have a location area exactly like the CNS. But each location area here has a bunch of routing areas. But the routing area is smaller than the locations. Each couple of sites forms a specific routing area. So each group of cells form a routing area. But each groups of routing area forms a location area. In Voice Network or CS networks. When I search for the subscriber, I searched for him in the location area. So I send the broadcast paging message to all subscribers. Dislocation area, okay? In the packet switching, what happens? I sent it to open subscribers in this rounding area. So I search per routing area, not per location here. This means that the routing area is stored as the FSGS and stores the rabbit areas of all its subscribers. So any subscriber that registers on the network does the area robbing update. So he can send to the GSM the last rounding area he was in. And based on that, if there were or there or downlink packets coming from the Internet and going to the GSM. The FSM sends those packets based on blast ramming area a bit that he registered on the STASS. So it's based on the last roaming area. This subscriber was available in. From here, I send a broadcast paging message on this routing area. So the owner, the owner of the PT MLP, will respond to the pockets he receives. All right. As we said, the location area identifier consists of Mobile Country Code and Mobile Network Code and location. Of course, all the location area that are available within the same network have the same country code. And the network code, what the difference is in location area code itself. So the location area identifier is different in the location area code. That is what makes a difference between one location area and another. How about the recovery area? You'll find the location area became a part of the rubbing it I don't mean that it is incited. I mean that the location area ID is a part of the welding area because all of the routing areas on the same location area will have the signal kitchen area. The only difference in the routing area code. I'm sorry, I wrote this here, the LAC. But all of these four together form the routing area identity. So the last thing in the location identifier's, which is the 2-AG site and the 3D site. And we said this part of this, yes. The energy cycle is called the CGI. So Google identifier. And in three G, I call it the service area identifier. The CGI consists of Mobile Country Code, network code, location area code, and in the end, the CI, which is B-cell identifier. And how about the surface here? It consists of Mobile Country Code, network, location area code, and service area. Let's talk about the user equipment identifies. First thing is the IMSI or MZ. We talked about it in the circuit switching, but we can revise it quickly in the packet. The MC is a unique identifier for any simpler. So any subscriber in my network has SIM card, has a specific identifier, which is the IMSI, which is an abbreviation for International Mobile Subscriber Identity. So what if you changed your SIM card or a problem occurred and you decided to sim swap or even lost it. So you won't. So you went to sorry, the mobile operator and you ask for a new sim card, your MCU will actually change because each SIM card has its own mz. So if you've got any US SIM card, you will have a new Mz. The MZ consists of Mobile Country Code, Mobile Network Code, and mobile station identification number. Of course, the MCC and the MSC are stable in all be MCs in my network. The only thing that differs in the MSN, which is the mobile station at amplifying or a deficient number. Each subscriber has different MSIS, then the other substrate in the user equipment identities. The second identity I have at apologize for that. So each subscriber has a different MSIS than the other subscriber. The second identity I have in the User Group bit identities is the M, ISDN, which is the mobile station ISDN number, which is actually your number. Depending on which operator you would. What if you change the SIM card? Will be MSD ISDN change? The answer is no. It's not related to the SIM card. The only identifier for the SIM card is the MD. Ms IS EM also consists of country code like zeros or two, for example, which is the country code of Egypt. Just a small example. And network destination code, like a number that starts with an example of 0, 0100. And it belongs to the Vodafone, or 011, which belongs to another provider, then the subscriber number, which is the rest of the number, which makes you special than another subscribed. So this subscriber number is what differentiates the MSI ISDN of the subscribers of the same network. Okay. Then I have the I am EI, which is the International Mobile Equipment identity, which is the identity to the hardware or the mobile equipment that you have. I always said this in the CSS, but it's also part of the PES course and also as a revision so we can actually use it. Again. It is an identifier for the handset itself. So if you were accessing the network with an iPhone 7, this iPhone 7 has a specific IMSI number. And this IMSI is different from another equipment that someone is actually using on the same network. What does the network use? This IMSI for? It can actually detect if this IMSI is stored. For example, it will be registered in my work that this is blacklisting. So I'll actually blogged a subscriber to our spine up. This IMSI may be waitlisted, which is the normal case, so we can actually access the mobile network will disappear. I have another identifier called the IM EI software version, which is the IHME I S V. This represents the software version on the mobile equipment. The software version on the phone makes a huge difference. As if I introduce the IMS network and I want my subscribers to make voice over LTE or vaulting. I can provision my subscribers. I need to start doing it step by step. So let's say the first step is that I will go with an example, an iPhone apps for example. So all the users with an iPhone X will be vaulted provisioned. So they will be able to do Cole's voice calls or calls voice over LTE. Sim me as a mobile network provider, I aligned with Apple and asked them to download a software version on iPhones or all the subscribers of iPhone X is that when the axis, my network B can be capable doing voice over LTE on the for genomics. So the software version does make a difference with the last user identifier is the Kimsey or TMS be Temporary Mobile Subscriber Identity. As we said, this TMZ is a number that I use to protect my IMSI or the MZ. So I let the user attach on the network with you while using or you would using the MZ. And when he's done with attaching me as a network, I send a request that whatever you do in the air interface between you and the site, you are connected. And actually. Or we can say, you can connect it or don't send it and introduce yourself to the IMCI where Mz, you need to know yourself, but don't introduce yourself to the MZ or send you another number called the TMZ. And who sends this TMZ? It's the SGC which is allocated, which advocated the TMZ to orbit subscribers. So if the user will left, this is as GSM and went to routing area or another as GSM. So this person will take in you TMZ from a new SPSS. What am I doing this? So I can protect the TMZ or this already. Mz are the, which is the IMSI of the subscriber. And as I said, this MC all stays with you as long as you don't change your zipper. What if someone could trace the data were pockets you set up in the air interface and trace your MZ. Sir, you'll be actually an open book in this case. So I'm protecting this important identifier called the ISR MC by giving you the temporary TMZ, the key MSI. We also use TMZ in pulling as identifies what, MSC or FSGS and this person is attached to by a value called NRI, the NRA value, which is the network resource identifier. So if a user sense that he wants to make a specific request to the BSC or RMSE. We will know where this request is going by the TMZ. As in the TMZ, there is a number which is the network resource identifier. And this is what tells me who this person is attached to, this MSE or this LLC or this LGN. So this is as far as the TMZ. As we said, when you are touching the network, you need to open a PDP contexts. This PDB context also has identifiers which are the NSAID PR, or this happy, and a small word, which is network layer service access port identifier, and PI, which gives the transaction identifier. So what is this API? It is an identifier for PDP in each access point. So for example, if I open a PDP contexts, so I can access the Internet APM. So this PDP will have an identifier inside the Internet APM. So this Ntozake differentiates my PDP from anyone else. The other identifier is the transaction identifier. This is for user identified. Both together distinguish the users on the APN itself. So MSRP or NSAID API is an identifier for the APN and TI is for the user in the APM. Alright. Now we actually finished the identifier part and hope to see you in the next course.
6. Interfaces in PS Network: As we said, this interface and this interface, any two network nodes that communicate together. And by communication, I mean they send to each other media traffic or cell signaling messages between them. There's an interface that controls this communication. This interface is important for you to understand as it makes a difference with you if you are going through an interview for coordinate work. So if someone asks you the interface, what is it or what is the GP or IUPAC. So you could understand and you can respond. What are the messages that flow between them as well? And also makes a difference in your job if you are working in the corporate sector or circuit switching or sector. And someone tells you there's a problem in the GM interface. So that means there is a problem between the RGS m and the GGAC, sorry, the SDS n and the GGAC. So there's a problem in the two nodes. So now you can start your troubleshoot. First interface is the IUPAC interface. This is the interface between the RMC and the SG, ASL and our UPS because it is in the packet-switching network. We said the orange with the MSC, the interface between them is the IU CMBS, because the MSE is in the circuit switching networks. So the RNC, where it communicates with the packet domain. So the interface with it is the IUPAC. So what if the RNC, when it communicates with the circuit switching domain, the interface is the IU, CS would be MSC between RNC and MSE. Of course, this IOPS interface transmits two types of data, user climb, traffic and control plans signal. Of course, this user plane traffic is the traffic itself, which is the data packets itself, which may be browsing or downloading or wherever you're doing. What about the control plan signal? If the signaling messages they use for doing a specific service, either by opening a PDB contexts or attached to a network. We call this the control signaling messages. So this interface, or UPS, transmits two types of data, which are signaling and user data. For the user data plan. Data, or let's say for the user plane data, what protocol controls the user climb down or moves the data packets from the RNC to the FSGS n, or the SDS n to the RNC is a protocol called the GTP, which is the GPRS Tunneling Protocol. And what protocol is responsible for moving signaling messages? It is the VP or called grana protocol, which is the radio access network application port. What are the types of messages that fall between the RNC and the SG ASL. You'll find a message like rap assignment requests for rap assignment response. If you remember, the RIP assignment requests is the Radio Access Bearer in which the SDGs and sends two RNC that there is a session that will open for this user. So please reserve a radio channel, a 3D printer for this person to send on in the air interface, and a message like rap assignment response, in this case to the RNC. The RSC responds by giving a radio channel to assign to this person as this channel. As this is a channel that you use when he sends packets on the air interface. Messages like paging masters, when this man is usually whipping, gets packets or downlink packets from the internet, from the packet data network moving TGS n to as yes. So the SDS and we'll need to find where this user X other GASGAS and nose is derailing area of the espresso, but does not know which cell this person is on. So the SES and sends the paging message to the IUP server interface, to the RNC. Then the RNC sends this message as a broadcast message. So it sends to all users in this rubble area would be Tim CRT, MSI. The message is a paging message which contains TMZ or T MSI, be TMZ identifier of this user which is supposed to receive this message. And the owner of this user is the only one who responds to this message. Another message, like the service request. This request is when the user himself sense to as gs n by the RNC through the IUP or the UPS interface. But why does it, but he said it as this user states or as this user states to the network. As I was idle or on standby, We will know the user's status in the packet switching network. What do I mean by states? That means if this person, if this person is actually opening a data session or not, is he registered or not? These are some states we will understand. But let me tell you when the user is idle and doing sessions, just sitting, not sending or receiving packets. So he's in a state called standby state. What if he decides to browse or download from the Internet? He starts sending messages called service requests. Messages through the IUPAC interface that represent this message is to tell me as GSM, that I woke up and we'll start sending packets of data. Another type of message that goes to the IUPAC interface, something called PvP context activation. In this case, after the user attached to the network, he has to pass to the UPS. He can't just jump to the FSGS at the SGR stem without reaching the IUPAC interface. If he is a 3D subscriber, Of course. As I said, a message is called PDP contexts activation. This user has finished and now attached and registered on the US GSM. And everything's okay. He now wants to start sending sessions or send packets of data. What do we need to do before sending packets of data? We need the PDP contacts between the user and the GG ESL. And what is the role or PDP contexts? As we said, it's like a logical tunnel between the nodes from the UE till the GG ASL. And its job is to move the packets or the data packets opposites fiber or not. Whether his data packets are coming from the subscriber and going to the Internet are coming to me as Damo packets from the internet and going to the subscriber. So I can open up, create this PDB contexts. I need to send a PDB contexts activation message in which the user sense and asked to create a PDB contexts. So we can connect to the Internet, EPM. So I can start sending packets to the Internet network. There's a message also that flows through the IUPAC interface from the RNC to the GSL. So that is as far as the RUP yes. Interface. Okay. So a universal a GP interface, which is the interface between VPC and the BSC and the SGR. This is equivalent to the IU PS interface, something like it. But the difference is the user is to G, a to G coverage or standing in a site with TOG. And the other user is standing under three G coverage. So this GP is the interface between BSC and as GSM is equivalent to the IU packet switching. In this case, the protocol but controls either the user plan or signaling messages. This interface moves usually plan and in the same type messages. So the protocol that controls both as B as SGP protocol picker, that the interface between the MSE and the BSC is the interface. The difference between the interface between the BSC and the MS, the GB interface between BAC and as GSM, as the interface, What's the subscriber wants to make a call? So here gives us a fiber, a radio channel with them during your score until the end of his car. But if the GP interface, the radio channel that I assigned to the subscriber, do I keep giving it as long as he's opening the PDP context. So should I continue giving him this chart? Yeah, Tourism. Here, I give you this channel only for a period of time, only during the activity periods. I will only give you a channel when you start some impacts. So this is the difference between GB interface and interface. The channels used in the air interface in which this person census data or packets in the air interface. In regards to the messages, the floor on the GB interface between the BSC and the S GSM is the same messages with the RLC, whether it is wrap assignment requests or response messages or paging answers, or breaking response requests. Pdp context activation, modification. All these are messages that flow over GeV interface between the BSC and SG, etc. Now let's talk about the GR interface, which is between the ACSM and bachelor. So this is the interface that controls the communication between ACSM and HLR. Does GR MOOC control plan or use or user plan or Bowl. It's a signaling only interface. So it only moves signaling messages from HLR to as GSR or as GSM to HLR. I use this year interface in signaling messengers like when you want to get user profile. So the SDS N During the attached procedures or when the subscribers attach on a network. The SDS and nice if take this user profile from the HLR so it can register actual are also registers. This STS, an address on which this user is available. So the GSM needs the driver interface to get the user profile from the HLR. And at the same time, the HLR needs to cheer interface. So I can register for subscriber on which SDS and address. Why does mTOR do this? Because if this person has any downlink packets coming from the Internet, you can know how to route the packets, are these packets to the GSL. So we can know which as GSM this belongs to or the subscriber belongs to. We know all this from the GRE interface, the PDP contexts that we opened for the subscriber. So you can move the data packets are received their packets from the internet. This PDP contexts is shared between the HLR and the USGS and through the GR interface. Okay. What protocol controls is communication with the GRE interface. It's called the MEP protocol, which is the mobile application part protocol. What are the types of messages that flow between SLR? And as GSM? You will find measures related to location as rubbing area of big, for example, or insert subscribers data. If the GSM wants to get the user profile from the HLR and insert subscriber data acknowledge from the other end, which is sent from the HLR to the SSN. So it can upload the subscriber profile to the S GSM. From the other end, the S GSM acknowledges that it received the data of the HLR also has a role in authentication parameters of the subscriber and says authentication info and authentication info response of these metrics. We have the GI interface, which is between the TGS n and the packet bad on. This interface is only to external networks. So the external network can connect to my network a packet core switching them. I have to actually use the GI network interface. Is this interface user plan or control plan. So do I send traffic or signaling molecule? It's only a traffic interface which sends traffic only between GSM and packet data network. Whether there's traffic is Domo packets coming from the Internet and go to the user or the fuser assembly. So it's coming from the GDS and I'm going to the packet data network or the internet. The GAN interface is between ACSM and GDS and take care. There's another interface between GSM and edge GSR. What's the difference between Gn, NGP? The gene is the interface between us energy, which is the as GSM and the GSM within the same network. But what if someone went wrong? In that case, the interface between FSM and GSM in the external network, this is the GP interface. This interface looks to be a user plan and a control plan as well. So it transmits both signaling messages. Also traffic on this interface. The protocol that controls the middle traffic or the signaling messages as the GDP protocol. But in signaling messages, I hope the ICU at the GDP C, which means GDP control, but unusual control. I copied GPGPU or GTP user. This controls the flow of media traffic or signaling messages. So what are the types of messages that flow on the GDP control protocol between the SSN, MEG, DSM. You'll find messages like PDP conduct context requests, which means a user wants to open a PDB contexts or a message like PDB context modification in which I want to modify NCPDP contexts. When do I modify this PB contexts? Take care that in the PLP contexts, there is a y of service that this PDP, so it controls the priority of this PDP on when to send or receive, and also controls the Big Bang. How's the quality of service or bit rate determined? It depends on the load understanding. So if the, as you said, is loaded as the number of subscribers that send or receive packets all at once. So in this case, I need to downgrade the quality of service for these users. Instead of using a bit rate of this, let's say XP or parent by half. So I'll be throwing your bit rate. So now I need to modify or to do multiplication in the PDB context. So I can modify the quality of service. So this message, most in the Gmail interface between the SDS and the GG. Okay. Now, here let's talk about the GE interface. This is between the GSM and the GCSE, and also between the GSM and the charging gateway and the GDS and as well, what is the GE interface? This is considered a charging interface, is the interface between S and G along with the charging game. So when the user makes better sessions and the SAG start creating records, call CDRs, which are called, or we shall call, which are actually an abbreviation for detailed records that are stored counting your usage. Cdrs contain amount up consumed traffic and amount of data sessions. These CDRs are created as long as you open a session with the Internet and are created and stored on the STS and the GG ESA. And by DJ interface between the charging gateway and as GSM, the CDRs are sent to the charging gateway and start the process yours. And start charging you as a subscriber and goes to the billing system to start off recharging. The protocol that controls all this in the GI interface is called the GTP protocol. Now, the last interface in the GIS interface, which is between the ACSM and circuit switching network, which is the MSC. This interface helps me as a subscriber or user to help me do a combine attached or to attach myself on the CS domain and the packet switching domain. Now this happens. I'm going to the GFS interface when I start sending either if registered first on the MSC, which is the circuit switching network. And when I sang or what I finish attaching on the MSC, I sent to the GSM. What if I go to the packet switches? There are three classes that you can go either connect to see as only four characters, CS and BS, or just connect to the packet switching hello. What if I want to connect unbox? It will be by the GFS interface. As you will send an attachment requests are pretty finished packet. Then you send an attached request to the CS as you register yourself on the CAS number, which is the circuit switching network on the MSC. This is all done by the GIS interface. The combined attach will also be discussed in the scenario spark when we move on.
7. PDP Context in 2G,3G Networks & It’s Characteristics Part:1: Now let's talk about PVB contexts. As a subscriber. If I want to send packets of data to the Internet, I need to actually attach myself to the packet switching domain. I'm talking about two G and three G subscribers. So they can send and receive packets of data to the internet. They first need to register themselves on the packet switching debate, or below the GSM. That's the first step. Now, the second step is creating PvP contexts requests. Inside this request, it states that I want to create a PDP contexts to connect to a specific API. After we send this create requests, there's kind of a PDP convex between the UE and the STS n and the g GSR. This context takes the packets from the user and sends it to JSON, and from JSON to packet data network. And also the PDP takes the packet from the Internet and goes to the user equipment. So the main function of packet switching domain is to provide connectivity with the external network. And so we can provide this connectivity. We must create a PHP contexts. This happens by APN hosted in the GSM. So the bottom line, I connect from user equipment to as GSM, then to the APN. I need to, I need to get to that in the Internet. And this APM inside or is inside actually be GSM. So let's give an example. As this mobile user wants to connect to the Internet, he will attach himself to the S GSM, then sends a PDP contexts request stating that he wants to take an IP from the Internet. Apn, which is the GSM. And in an APM is an IP pool, energy gs. And we'll take one of these IPs and give it to the user. And tell him this is the IP of the PDB context that he opened, or the IP that will route you to the Internet. So the GDS and automatically takes the IB and attaches it on the PDP contexts that, that this person open and attached to this PDP is the Internet, actually the internal IP. So now this user has one IP address from the internet. Of course, these APMs can be hosted on one Gigi has had take the APM and hosted on another GSM. As I have a variety in this part, to be honest, depending on the capacity of each category. Of course, any PDP contexts created has a specific quality of service. And the quality of service is something that controls the big way that you will go to. Then Olivia phrase that again. So let's say the boy, you've service is something that controls the bit rate that you will actually go to the Internet width. And this is the priority that you send first or someone else first. And is the BP contexts that you created have the priority December 1st or shouldn't wait. All right. Now we understand the PDP convex. So what are the characteristics? Now? What are the characteristics or parameters or important things that are inside the PDP convex. First, you find the PDP address. And second thing is the quality of service. The PDB address is the IP address assigned from the APN to the GGE SM to the PDB contexts. So the user wants to connect to the Internet. He needs to take an IP from the API Internet APM, so we can go to the internet network. So this is the PDP address. I assign this PDP address to the PDP contexts during the PIP creation, the GSM sensory science, the IP address or PDP address to the PDB contexts. Now, the second thing we have is the quality of service. And by the way, I use, you can create. More than one PDP contexts. And why does he do that? To be honest, is it's due to the quality of the service as the packet that flows on this PDP contexts needs a specific quality of service. What if he is going to do multiple things? This will show more in the EPC, which is the Evolved Packet Core part. I'm explaining the EPC as a gateway to the IMS step C, you can connect on the IMS and do voice over LTE. A voice over LTE call that you will need signaling and voice traffic. But in the IPPC, you create something called a bearer, The EPC network. This bearer is equivalent to the PDP context here. So when we go to the 40 part, we will hear a terminology called bearer, default bearer and dedicated bearer. What is default bearer is the main bear, which is the, which is equivalent to this PB context. It can carry, for example, the signaling of the IMS network. So if a subscriber, once they attach to an IMS network, he will start sending some messages. And if he wants to make a call, you will start sending signaling messages. And the EPC. Then from the EPC, it will go to the IMS network. But the flow of signaling, doesn't it have a specific quality of service, which is different than the quality of service of the tropics speech. Actually, yes. So I need to open a default bearer to signaling and another bearer, dedicated bearer to another quality of service to the speech traffic itself. Now, let's talk about the quality of service. Now, the quality of service in general is the one who defines the priority of the subscriber in when descend, as he is opening specific PDP contexts with the internet. And there are millions opening PDP contexts, but loosens before who. This is decided by quality of service and the bit rate this person is on as this person depleted his credit. So I put him on a lower speed. Who controls this betray is the quality of service. What are the parameters inside the quality of service or the most important attributes in the quality of service. You will find traffic class, something called the RP value, which is the allocation and retention priority. And maximum bit rate that is available for this subscriber. Who assigns the quality of the PDP contexts is the GSM as the GCS. And during the PDP context activation or during the user is creating a PDP contexts, the GDS and goes to sign a quality of service to this PDP convex, which has a traffic class r value and maximum bit rate. Now, the traffic class is the type of traffic class itself. Whether it's conversational streaming or background traffic. What is conversational? It's like the charring. What is streaming? It's like video streaming. How about interactive? It's like playing games or games online. What about background is like downloading all of these examples, but there are a lot of traffic classes, but these are the most important ones. What is the factor that affects its traffic? It is the least sensitive. So this traffic is either delay sensitive or delay insensitive. Something like a conversational voice or conversational traffic, like Skype or WhatsApp messages. Those and delay sensitive as it's not a naught is not normal that you're chatting and delay happens. Is delay insensitive if you're doubling something and you don't take care of the damaged speed while you are on the background of your phone. And in Lake heard, you realize as you are downloading with the bit rate of, let's say, five megabit per second. And it went to 4.5 or four, maybe in three. You actually haven't realized that. Right? Now. The second thing in quality of service is the ERP value, or so-called allegation of attention priority. I uses ARP value when the network nodes have a problem with the resources. Let's say you have a, a 100 subscribers that want to open data sessions. And the resources that I have. I don't much as I have only 90. So what do I do in this case? I start looking at the ARP value of each PDP contexts of each subscriber. In this case, if I have a 100 users and money channels or resources, I will have to neglect 10 of them. And I'll have to give resources to the other 90. And those 90 will be chosen depending on their ERP value. For every PDP, there is an ARP value that is from one to three. As one is the highest priority and three is the lowest priority. And for every PDP, there's an ERP value, which is the allocation and retention query value. And in this quality of service, I can decide what is the maximum bit rate this person can receive. As the bit rate in packet-switching is variable and changes. So I decided maximum bit rate for this quality of service. Quality of service is three times requested, subscribed, and negotiating. These are all the types of the quality service. Let me rephrase that in the slightest what their cost the quality of service is when the subscriber sends a PDP creation so he can send or receive packets from the internet. I want to open a PHP contexts with a specific quality of service. This is the requested quality of service. Now, the second type is subscribed poly observes. This is something available in the user profile as the GSM takes it from the HLR. As when this person subscribed to our network, what he be subscribed to, even have subscribed to specific speed. So this quality of service is very specific. Third thing is the negotiated quality of service, which is the type of service that the GDS and assigns to the PDB contexts of the subscriber. Now, let's imagine that this is a user and this is the GSM, and this is the GGAC. So the user sends requested quality of service. So the, so the GSM went to the HLR and got the subscriber profile during the attached process. After you better profile. So it now has the subscribe quality of service. Then the S GSM was start comparing between their cost of quality of service and the subscribe columns. And does this person have the right to take use quality of service or not? The GSM validates this based on the quality of service for this user which had got from the HLR during the attachment process. And after it's done with the validation, it sends the results to the S GSM, and this result has the negotiated quality Offsets. Then during the PDP context creation, the GSM assigns the negotiate quality of service and DPP contexts. Thank you so much.
8. PDP Context in 2G,3G Networks & It’s Characteristics Part:2: I guess the last time we spoke about PDP contexts. Now, let's continue the PDP. The main goal discourse as we're talking about packet switching, connectivity service. Now what you see in front of you is the packet switching activity service. In which how the user equipment can have connected East service with an external data packet network, which is the Internet. The main purpose of this connectivity service is for him to actually send and receive packets with the Internet. So I can send packets or traffic of packets. He must have a PDP context, which is a packet domain protocol caught. It has a tunnel between user equipment and GSM. And by this tunnel, I can move my packets on it. And when it reaches the GGE SM, it goes to the internet. This happens by the APRNs in the GGE said. And as we said, the GSM has an API, which is the access point name. This APN has a range of IP, which is considered IP pool to it or to the external network. For example. Inside this GSM, I have an intranet APM. And in this Internet APM, there's a range of IPs for the internet. So any user who wants to go to the Internet, he takes an IP address from here, from the internet VPN, to access the Internet. If we give an example for the user put pins in this picture, he has packet-switching connectivity service with the Internet. But how or how does this happen? You'll find him connected to the SDS m and the SDS n to get an IP address with its PDP contexts. So it took an IP address from the internet VPN to access the internet. So now he is considered to have open a PDP context. You can consider the Internet APM as an access point. So the mobile device or the mobile equipment will connect to the Internet, APM. So it can connect to the Internet. So any API and has an IP address range. So the mobile device will take an IP address from this IP range to access the Internet. The APMs can be hosted on one GSM or multiple GDS ends can host multiple APMs. It all depends on the design of each operator. And as we said C, you can access the internet or send or receive data from the Internet. You have to create a PDP contexts. Okay? So go to the other slide. Any PvP context has specific characters or characteristics. The most important characteristics are the PDP address and the quality of service. Let's talk firstly about the quality of service during the PDP context creation or when the user equipment attaches on the USGS n or registered on the USGS n, or packet-switching core network. The GCS n starts creating a PDP contexts for this huge, we will of course see this process in the procedures chapter. But during the creation of this PDP contexts, the DJs and starts assigning quality of a service to the PDB context. So what is the, what is this quality of services aptly describes the priority of this user. So it describes the priority of the PDP, context of the user equipment compared by the other users. So let's say I have 10 users. I see what order is this person in to send or receive data. And also it defines the bitmap for the traffic. This user will do. Like, let's say, So what do we face the part again? So devise a bit made for the traffic. And it also defines, or let's say, what is the maximum between this year and a half as well. All right. Now, if I talked about the most important attributes about the quality of service, we will find traffic class, the AARP, which is the allocation and retention priority and maximum bitrate. The traffic class is divided into four types. Conversational, streaming, interactive, and background Prof. classes. These classes or the traffic in general, what makes an impact on them? Is this strophic delay sensitive or delay insensitive? That's the answer to this one. So an example, I, conversational traffic like WhatsApp. It is compositional traffic of WhatsApp or Skype sensitive or not. So is it the resistive or delay insensitive? It is actually the least sensitivity you can when something, as we said, and not arrived and type something else and rise and then type another thing and doesn't write the organism just make any sense. So this is affected by the light. What is not affected by the lane is something like background traffic. So if you're downloading something with a big group of 500 kilobit per second. And it went down to 200 kilobit per second. But it is in the background and you can see it. So if there's a small delay, it won't remember. All right, So the second attribute in quality of service is the allocation and retention priority. This is used when the network nodes have a problem in its resources as it can offer resources for all users. So let's say if the number of users that use my packet core or too much, all of a sudden, the oversight, open data sessions or what's a machine not putting for each resource, as my design doesn't depend on how many neutrons I have my design. And it's how much did the peach or peak, sorry, peak reach. Now some operators tell you that the design on peak. And a peak is the number of sessions that the cell happened. Or that all happened at a time. At some operators say that they designed an average for every face that part. Some operators that say they design on average the peak is actually none of my business on, on my concern. Let's say an operator actually came and design on its peak. And it's peak allows it to do a million sessions or watts. So he saved resources for a million sessions at a time. But then a new peak arrives or arrived. And I wasn't prepared for it. And the number of sessions that needs to be created or number of users that want to access the Internet is a million and let's say 50 thousand. So there are an extra 50000 users. So what do I do? I need to look at the ARP of the PDP context of all these users. I'll give the priority for the ones Ashley, or who have an ERP value, maybe one or two, to actually send heresy in which one is the highest and three is lowest. So I can take 50000 of ERBB3 and make them wait. Of course, the PDB context has the ERP value, not the user, and is from one to three. And depending on the ARP value, is this person allowed to send now or should he wait till the resources problem is actually resolved. The third attribute is the maximum bit rate, which is the maximum pygmy assigned to APP contexts. We said the types can be requested or the types that can be requested. I'm sorry, let me rephrase that program. There are types of PDP contexts like the requested quality of service, subscribed, negotiated quality of service as well. What's the difference between them? They're posted quality of service is what the user requests and is already attached to the network. And now wants you to create a PDB context. So you can send traffic or receive traffic. This user sends or creates a PDP trapping and asks that I want this specific quality. And once a high quality of service, this request goes to the SDSS. And the SDS n has the UE subscription information. So the SDS and knows what this user is subscribed to. And as a lump, a bit big of a certain amount? Or is he a high value or low value customer? So on. So I can see what is ERP value is one or three or two. Now all this is the, all this the S GSM nodes. And then it takes this quality of service and compares it with the subsequent quality of service and the subsequent quality of service. If the service available in the user profile and be as GSM. In which the SG SN got it from the HLR during the attach process. So let's say the S GSM, for example, of course, told or let's say, found out that this user is asking for something more than what is allowed for it. So it will actually downgrade the quality of service in where it will give a negotiated quality of service. So this is the quality of service I will send to the GDS F, which will look with the PCRF if there will be a specific ERP applied or go to the OCS. So VGS and confirms on the quality of service on the PDB contexts, which is negotiated quality of service. Okay? Now, we stopped here last time. The most important characteristics for the quality of service is the PDP address and the quality of service. So what is the PDP address? It's the IP that is assigned to the PDB context. As I mentioned, the user first attaches to the SDS and then decides to create a PDB contexts. Pdp context is attached to the APM that this user wants to conduct them, which is attached by an IP address, which I take from this patriot API. As we said, this interrupt APM has an IV pole so the user can access the Internet. He goes to the Internet, APN and takes an IP address from it. So you can access via the Internet, let this IP address the GDS and assigns it to the PDB contexts during the PDP contexts activation procedures. Of course, this IP address is assigned by the GSM. The user equipment will use during the vaccine or accessing process of the Internet. So now I have two types of PDP errors, which is the dynamic and static. Dynamic as the IP I take from the Internet APM. So I decided to create a PDP contexts to access the Internet API. So I take from the IV pole, which is in the intellect APM, an IP address. And this IP address is actually dynamic. So what if I close the PDB contexts and decided to reopen them? Once again, I will take a new IP address in this case. And another type of IP address, It's called these tiny. This is the user IP in the network itself. But who does this? During your attachment on the network, you are given an IP address which is available in your user profile. And the SDS n stores this IP address as the SG SN goes to the HLR. So it can take the user profile and asked Is asks it for a copy of the report so I can register it. And from this copy, there's a subscribe quality of service, as we just explained. And they're just static IP address, which is the IP of this user. This static IP address, I put it through the PDP context by the GSM. During PDP contexts activation procedures. And during this time, during the PP contexts activation procedures, we sent a static IP address to the GSM. So the GCS and assigns the static IP address to the PDB context. So the PDP contexts has a, you can say, let me rephrase that point where I can see the PDB contexts actually has an assigned as is assigned to two PDP addresses which are dynamic and static. Now, dynamic that VGS and took from the internet API. But the static is when the GSM took from the SCSS and then the ACSM got it from the user profile. Okay? So the dynamic IP address, as we mentioned here, the GSM assigns the IP from a pool of IPS configured in the GSR. So in case of dynamic, every time the subscriber requests a PDP, it takes a different IP, but a static IP address. The static PDP addresses exist in the UE's subscription data already. Now, the IP address can be RIP version of IP version four or IP version 6 or IP version 4, version 6, dual stack. And this type of PDP is available in the UAE. Subscription information.
9. PDP Context in 2G,3G Networks & It’s Characteristics Part:3: Now, let's talk about the feature only in three G, which is called directory. This is a feature only in three G networks and not to G networks. The purpose of direct tunneling is to actually decrease the load from the SGC. The whole idea of direct tunneling is not flat. The SG SN, one has signaling and traffic, but only to a signaling. So I save 50 percent of the workload on the GSM. So the network node used to work in signaling messages as a, let's say, process the signal messages and at the same time bypasses the media traffic or the packets of data. So we did direct tunneling in which I bypass the GSM from the data or traffic. Now, let's see if the direct tunneling is not used. What will happen? You will find a traffic flow or user plant flow will pass from the orange to the OR to the RNC to as GSM to GGAC. The same for the control plane or signaling messages, which will also pass from the RNC to the as GSM to the GGAC. In case direct killing is used, you will find the control plane will pass from the user to RNC to as GSM, to GSM as nothing changes. However, they user plane or the traffic plane will pass from the user to RSC and direct to the GGE SM. So the user plane will flow directly from the RNC to do GSM and leave the SES and end the control plane as it controls this message or the signaling messages and the slope. So dark echoing can happen when the SUS and is the one who decides to do direct selling or not. Because just the care in three G, not all of them work on darkening. You can work on direct tunneling on some RNC nose and some as GSM nodes. And it may not work with direct on. So direct tunneling is determined by the RNC and as GSM that you're on. So if you're attached on an FSGS M that doesn't have this feature. Or I didn't configure either a tunneling feature on it. And the same goes for RNC. So our Goldie, by the normal force from the RNC to as GSM to GGC. And what if I configured the direct tunneling feature, then the flow will be from RNC to G2M dark. To activate direct tunneling. The GSM plays an important role here in control during PDP contexts creation the SDS n, Since the RNC address to the GSM. And in the same time sending the GCS and address to the RNC and body two addresses they can communicate with each other. And this is one of the procedures we will see in the scenarios chapter. And by direct tunneling, we were able to minimize the lead on GSM, which is actually much better at the moment. Now, let's go through the other part. Now. We have another thing called the GTP tunnel and tunnel and ID. Any two nodes that communicate together in this user time by the GTP protocol. Recall the medium or passed between them, the GPT, ddNTP Talmud alternatives. So for example, any two nodes, whether SDS n with RNC or FSM with GSM or RNC with GSM. If the protocol that controls the flow of user played plane or traffic plane between them is the GDP protocol. Then we call the medium or pass between them, the GTP tunnel. This GTP tunnel is a part of the PDP contexts. And as I said, I create a PDB contexts between the user equipment, energy, GSM, this PDP contexts. Or let me rephrase that part where I said, so this PDP contexts, the GTP is part of it. All right? So let's say for example, that I have a cell or that I have. All this as the PDP and this GTP, GTP tunnel as part of this PDP. Now, let's see the GTP tunnel in two G and three G and how direct selling is there as well. Now, in 2D, you'll find a two nodes. The only nodes that communicate with the GTP protocol are the GGE, SM, and the SDSS, and communicate by GDP protocol. And between the BSC and the S GSM, there is a protocol called the PSS GP protocol. So here, the user plane between the SGAs M and G GSM is GDP, in which it controls the flow or traffic between SAS EM to GSM, or GSM to, as GSM. It is called the GDB protocol. Once again. Now, in Fiji, you will find the user plan for the user plane from the RNC to SDS. And it is the GDP protocol. And from CSM to GSM, the GP, the GTP protocol also controls it as well. So GTP tunnel into g is between LGN and GSM. But in 3D, it's from RNC to as GSM and from SAS EM to GGAC. And indirect tunneling in three G. And let's say I decided to activate direct tunneling protocol that communicates the user plan flow from RMC to gigi S M is the GDP protocol. So the GTP tunnel is between RNC and Judaism. And again, the GTP tunnel as part of the PDP contexts. Let's go to this one. Now. Let's see the tunnel end point identifier or ID. Any GTP tunnel. As an example, in the two G network, I have a tunnel between as GSM and GDS. And any GTP tunnel is identified by Konoe end point identifier. Both as yes and and GeoJSON have total end point identifiers. But what happens during the PDP contexts creation? As I said here, this S GSM has eternal end point identifier and the same as for the GDS and which has another Tom and point identified during the PDP complex creation, the as GSM, since it's some endpoint identifier to the TGS and vice versa as the GSM also sends its Tunnel Endpoint Identifier to the CSM. So the ACSM has the GSM Tunnel Endpoint Identifier, and the GSM has the SES and Tunnel Endpoint Identifier. So now identify the GTP tunnel between these two nodes. Once I identify the tunnel endpoint identifiers and create the PDP contexts. The traffic flow will now move from user equipment to JSON and from JSON to external better path network. But what is the process in 3D tunnel again, the RNC, more sun, It's tunnel endpoint to the GGAC and the GDS n will send its Donald point to R and C. And once this happens, but it should be tunnel is created between the two network nodes. And after I finished the PvP context requests procedures. Now, the traffic or my data can actually flow between the two nodes. Thank you so much.
10. UE State Management in PS Packet Switching Core Networks: So let's talk about a new subject called User Equipment state. Management in the packet coordinate works. What is the user Woodman states? So the bottom line is that this user is in the network. Is he lying or not? But he said beta or not. Instead, my state or not. These are the states we're going to talk about. So we will know the types of states in the 2D and 3D networks. Okay? So we have something called the MMS state, which is the mobility management state, which is the, which is a parameter which is always in the user profile. So each user profile has a parameter called mobility management state. This parameter indicates the status of this user from the mobility management perspective. So is this user idle already sends or receives data or even on standby. This parameter indicates bus subscriber status from the mobility management perspective. So if we talk about the first day, which is the ready state, and are talking about the users that are in the 2D coverage, not the 3D coverage. So if we talk about the ready state, in the ready state, if the user of this MM state is ready, this user, the network nodes on which service users are. Let's agree that any routing area consists of many cells, end users attached to a specific cell. So if in this routing area it contains from, Let's say, someone to sell 100 as an example. In case this user is in the ready state, this means that the network nodes on which cell the users on. So if he's on so 123 or even four to 100. So the network in ready state knows where this user is. So why does it known as the user in the ready state sends and receives packets. So he's active learning sessions, whether browsing or even dabbled. We will know the scenarios chapter that before the user receives downlink packets coming from the Internet, sends packets, the user must notify. First, this is on the SG SMR. He must have the cell ID the user is on before it allows him to send packets, are received packets. Since this subscriber is in the ready state. And the ready state means that the user sends and receives packets. So this automatically means that the network on SES n knows the CGI, The cell ID of this user. So when is this user ready? After he attaches? So once he attaches, this user is ready. So automatically we have to translate that this user attached and open a PDB contexts. Because as I said, when the user is ready, that means he is sending. So he's acted on the Internet as he's sending and receiving packets. The second state is the Standby state. Infantilized the network nodes on which wondering area the user is available. But doesn't know on which side. Since the network doesn't know he's on which cell, that means there are packets sent from user to the network or no. Actually, it's, you know, the network now on which cell this person is on. In case this person sends packets, as when he sends packets, he has to send is CGI. So since he is in standby state and in this state, we said the network or no except the routing area, but doesn't know the cell or the cell ID. So there are no packets in the standardized data that is sent from the user to the SG. When does the user enter the Standby or moves from ready state to step-by-step. There's a timer available on the issue of equipment. And as JSON, and this timer is all ready, timer expired. This really timer, once this user sends a packet, this ray timers such actually working. But what if this ring timer expires and it started counting three seconds and no packets were received or sent. So the user automatically changes from reading to stand why. So let's say the ready timer. Expired and the user decided to send or receive packets. So the user himself will change from standby to ready. So if the PDU or the packet direct transmission occurred, the user is actually ready. Okay? The last day in two j from a management perspective is the island state. When does the user go up? If the user detached from the network, in this case, then I work doesn't know where the user is. The user is unreachable to the network. So I don't know where he is on and which running area. So once the user detaches, so he moves from idle to Augustine actually. Alright, let's go back a bit. And the last thing I just wanted to say in the Standby state, in to g, the user reserves radio chance already resources, which he sends traffic in the air interface. And in case of tan y, what is the fate of the radio resources? I want to take these radio resources from the user and give it to someone else. I'll leave it assigned to this user, but I can actually share it or share these users, which of these resources with other users? Okay, so let's move to other small part. Now. The mobility management state, or states in three G, I call it the P m, m states, which is the packet mobility management state. There are three types of these states. The PMM connected, the PBM IDO, the PBM detachment. What's the difference between them? They have different names with the same ideas. The first stage is the PNM connected state, which is close to the ready state in tutti. The PMM state means that the network knows that the user exists on which cell. That means that there are packets that are sent and received between the user and the data network or the external dinner. What is this user PMM, or connected or in the BLM state? When the user is attached on the network. So the user opened PDP contexts. So the user is in the PMM station, or the PMM state in the 3D networks. The second status in the BMs Island, the desert second state is the PMMA IOL. The pin idol is equivalent to state-by-state in to the Standby state occurs when the user passes the radio time. Expiring as the user stays, are longtime not receiving or sending packets with the Internet. So then the user moves from PMM connected to PNO. In case a 3D, it's different. I removed the resources completely from the subscriber. So what's a subscriber sense of a packets? Or start assigning resources once again. The third type of or the third type is the PMM detached state. In this case, the network doesn't even know where this person is and is unreachable and the SES and can even find. So this person's status is now PMM detached. When does the status change from connected to the touch? If he tried to detach or detach or if he tried to attach and a rejection occurred for this attach. And he actually tried to do around the area and even couldn't. So he's unreachable. So all this leads to the user becoming PMM detached. These are all the mobility management states in 2D and 3D. The last thing for states as well, there's something called Session Management states. The session management state tells you that the PDB construct contexts that you open. So what is current status? I have two sticks. Is the session or PV contexts active or inactive? Active means the PDP contexts has packet transfer. Some easy user, I send packets on inactive when or if. I'm not sending packets on the speed because one has the PDB contexts moved from active to inactive and from inactive card. In case the user created a PDB context creation and inactive if I repeat the context in activation or in case the user detached from the network, then his idol into g or PMM detached in 3D. So this PDP contexts is inactive. So session management states describes the state of the PDB context is active or inactive.
11. PS Packet Switching Core Network Contexts: Now let's talk about the packs which in core network contexts. Okay. What is this context? The databases that I have and are considered NB packet port. So if I compare it to the CS, the circuit switching core, you will find the contexts will be found in the VLR. What is the visitor location register? That is in the MSC, which stores the subscriber data or subscriber profile on it. And MPS, what happens? You'll find two contexts. Mobility Management Contexts and PDP context. What is the mobility management context? It provides, but all the information of the mobile user, User Equipment. The PDP context is the context that supports packet delivery between mobile solute, mobile station, and network. We will consider these two tables, which are the mobility management context, which is in the mobile station and be as GSM. So in any user equipment and any GSM, there is mobility management context, which is the MM contexts. The PDP is a table that is inside User Equipment and in FSGS n and m, g GSM. What are the types of data in the Mobility Management Contexts? You can find the IMSI of the subscriber or the mobility management state. Is this special idle already or standby in case of 2 g, of course, in cases of three G PMM detached or BVM connected. And also we can find the TMZ of a subscriber or EMI, which is the EMI, sorry, which is the Equipment Identity or the MS ISDN, which is his number. And we can find which welding area or the last routing area of that as well. We can also find DVR address and there is a combined attach, which is CS and BS attach. And we will also see is procedures. We can find the SDS and addresses, the authentication triplets or even subscriber charging characteristics. So we can identify a subscribe on which plan exactly. All of this is available in the mobility management context. As for the PDP contexts, which has the PDP information, we will find the PDP context identifiers as MSRP and TI. We will find network access point identifier's with transaction identifier. As we said, MSRP is an identifier for each ABM. So each APM has a specific miss Obi. Let's go to the part where TI is an identifier for each APM, for each user. That means the user is identified in this APM with what exactly are with what? Also it has a PDP state. Is this PDP active or inactive? It also has a PDP type, is this IP version 4, 6 and it's up. It also has a PPS, static or dynamic PEP. The study, as we said, is available in the UAE subscription data and is sent from the SDS n. And where did they get it from? As a guard from the new subscription information and took it from the EHR. And what does agile are due in this static IP sends it to GSM, and the GSM assigns it to PvP contexts. And this is a part of the information that is put in the PDP contexts, which is the static IP address. And the dynamic as well, which is a static IP address on. So as for the dynamic, dynamic as the IP that I take from the Internet API to access the Internet. And will change every time I open a new PDB or a new PDB contexts. And also the APN in use. So it figures unconnected on which APM is that the Internet, corporate or IMS or where ever the epi and the quality of service profile, which means the trip, the packets that are coming, what priority are they? And what is my maximum bit rate? Or the maximum bit rate that I can actually flow will be Tunnel Endpoint IDs for each GTP channel or GTP tunnel, I apologize, which is MVP contexts. So for example, this PDP contexts is on three G network and this 3D network supports that are tolerant. And in direct tunneling, the GTP tunnel is open between the RNC and G-CSF. So the GTP tunnel endpoint IVs that can figure this GTP will be stored on the PDP context. Also, it has allowed the, it has the allowed BP l m, n, which is the visiting network. So if I travel and the woman in any country and went to a country in which they're, the network does specific restrictions. So anyone allowed to connect on it has to introduce himself to the PDB contexts. Also the charging characteristics which you subscribed on a PDB contexts. So there are two contexts I have in the packet coordinates. Alright? Now, if we were to come to the timer, which is the mobility management primary functions in the backend core network. Oh, and I forgot to mention, let's let me just ask you a question. First year. In this part. If I send an SMS, the radio resource that I will use here, will it be stored only MMM contexts, already PDB contexts? The answer is the MM context, as it is assigned to signaling. Only. An SMS is only a signaling. Therefore, I don't need a PDB contexts to send SMS. So I will need mobility management context only. So anything associated with PDP contexts, israeli to traffic or user flow.
12. Mobility Management Timer Functions in PS Core: Now, let's talk about the mobility management timer, which is in the packet core or PS4. First timer is the ready timer. The main function of the timer is to control the mobile station to remain in a ready state for a certain time. Let's go through this part. So the first time or is there any timer? And as I said, the main function of the rate climber is to control the mobile station, to remain in a ready state for a certain time. When does the mobile station remain in realistic? As long as it is sending and receiving packets. When does the ready timer actually function? Once you send a packet there, ready timer begins to function. And also once you receive a packet as well. So let's say the ready time or duration is 36, three seconds. And it's just a small example. Let's agreed that the rate timer works with two scenarios. The first scenario when the user sends a packet, and the second scenario is when the GSM received the packet. And once it receives, the ready timer starts functioning. In both cases, they're ready timer, for example, stays for five seconds, and it stayed for five seconds. And after that expired, the mobile station will move from the ready state to stand by state. So they're already timer is available in user equipment and as GSM in where it counts five seconds from the last packet sent or received. And after five seconds, if the user didn't send or receive packets from the as GSM, the mobile will move from ready state to stand by state. But the 50 seconds is just an example. Nothing else. Now, the second timer is the periodic routing area of the timer. This timer monitors the routing area of the procedures. Let me tell you that the 3D timer and the periodic radio, a bit timer go to the mobile station. And they go to and during the attaching on the network. And when you're done attaching, you registered on the Internet and you're done registering on the network. Then you send a message called Attach Accept message. The network sends it to the mobile. But in the Attach Accept message, you put the ready timer and the periodic routing area of the tire. See you put the length of each type. So both timers are available on the mobile station or the user equipment. So the periodic routing area timer monitors the periodic routing area API procedures. Once the periodic routing area a bit expires. So this user needs to do periodic routing area of the tsunamis and network. I inform the user after each five seconds to do a periodic routing Area Update. Again, it's not five seconds. It can be an hour, for example. When does the periodic routing area timer begin to function or actually count? Once the user goes to standby, state me as a network, we start the counting, we start counting periodic reading, periodic routing Area Update. Because as long as he is in the ready state, I know where this person is because I already have is cell ID and he's sending and receiving data. So I know everything about this person. So let's say he went to standby state. This means he stopped sending data. So in this case, I don't know where the person is. So I'll start counting a timer, for example, like an hour. And when this hour is over, I ask you to please do a periodic browning Area Update. How about in this hour? If this person sends or receives packets, so this timer will be interrupted. So this person will go to a ready state once again before the hour expires. So a condition in the periodic routing area update, the whole hour must become nothing interrupts. And after the hour passes, the user needs to do routing area. Now, the third timer. Is the mobile reachable or the mobile yes. Demo are reachable time. This timer is available on the GSM. It's function is to monitor the periodic routing area, upbeat procedures. So it matches if the surrounding area have been, are not actually the same case. With the mobile reachable timer. It's almost close to the preoptic area up in timer, but looks like it. And as the mobile reachable timer doesn't function, except if the user goes through step-by-step. So it doesn't count until the user goes to standby state, where the difference, if I say that the periodic rubbing Area Update time is one hour. So the mobile reachable timer will be three hours. This starts with the Standby state, and the latter also starts when the user goes to the Standby state. And automatically, if in these three hours, the user sends or receives packets, the mobile reachable timer will be dropped. And I will start counting over again. Once the user goes to standby state. As I said, the mobile reachable timer duration, for example, is three hours. Then in-between these three hours, this or there is considered to be three periodic routing area updates that must happen. So for each hour, aperiodic, a big must happen for three hours. What if this person is missing the periodic routing update? If the mobile reachable timer finishes the three hours and we couldn't reach this user. In this case, the SG ASM, automatic, automatically raise a flag. This user is unreachable and it is called a PPF, which is the paging procedure fact. They use of this flag that if download link packets arrive to this user and this user is unreachable, then I won't pass it and won't reserve any resources because I know that this person isn't available. The fourth timer is the implicit detached to Tyner. This timer is also on as JSON. And this timer starts to function once the SDS n put an unreachable flag on this user. Let's say that this timer is one day. So if the person stays a bailed out a building or packets or do anything at all, then GSM automatically detach the subscriber. And we'll also erase his context. This person passed through the implicit detach timer without contacting the network at all. So the user, instead of being standby, is now an idle state. So in idle state, this user has been detached or he asked actually to be touched. Okay, so let's revise things again very quickly here. The periodic crowding, upbeat. This happens when the user gets out from the ready state to state by state. Then this user became unreachable and we couldn't reach him, and he is now on state-by-state. Then the implicit detach timer worked and started coming and finished, or it's timer expired. Once this timer is stopped, I will be touched a subscriber, which means instead of this subscriber, instead of the subscriber is on standby, he's now on idle state or detached or a v dashed or, sorry, a detached subscriber. So now we finished the timers in the packet core network. Thank you so much.
13. PS Packet Core Procedures: Hi guys. Today we'll be starting the basic procedures that the user does so he can start using packet switching services. The important procedures is that the user attaches on the network so he can send and receive traffic. With the external packet data metrics. He has to attach or register on the network and also needs to do a PVP context activation. Attached means the user will register on the network before using data services. And in this process, the FSGS and we'll allocate user information or retrieve user information from the HLR. And also authenticate the subscriber if he's authorized to access this network or not. The second step will open or create a PDP contexts in which he creates a tunnel. And this tunnel will transfer the data on it or receive it as well. And after creating a PHP contexts, this user is ready to send or receive packet data would with the external packet network. So these are actually the basic procedures for the user to send or receive data array. All right. If I said that this is the high-level attach that the user's sense attached requests to SG ASM. As the content of this request is that the user authenticates on the network. As the SDS M checks if this user is authorized to use the network or not. And the second thing is that the GSM activates the cypher it as if we said, like let's say if there is a ciphering algorithm, the GSM will send to the user or access networks, whether it's 2D base station or RNC, it will start sending the ciphering algorithm and ask them when they say, let me rephrase the part where we said here. When it sends the ciphering algorithm, it as the Monday send the data on the air interface. So please send IT side for it by this cipher algorithm. Third thing, we will do location update to the subscriber. So the GSM can retrieve the subscriber info and take the subscriber profile from the HLR and store it. And second thing is that the HLR takes the address, the DSM that this user is attached up. So the Agile or nose on which as GSM is this person registered as if there are any download downlink packets coming to this user. The Agile or knows where to move these packets and on any S GSM. And how would know by the GSM add restored in it. And the last thing is the TMZ allocation. As in the last of the attaching process, the network or SES then allocates CZ to the subscriber and tells him in the future transactions when you send data or signaling messages, sent it, and introduce yourself to the TMZ and the MZ. Second thing after it finishes attach, it starts to open or request or create a PDB context. So he can send or receive data would be external network or external packet data network. Here. Now, here is the signaling that happens during the attached procedures. First thing, the user will send, attach request to the network, and this request goes to the SGR. But what are the parameters in this attached requests? So the user will acknowledge himself. In what way? In this attachment loss? This will be done by the MZ because he's attaching to the network for the first time. So they didn't allocate him at TMZ yet. Here, the FSGS and we'll start authenticated and check if this person is authorized to access the network or not. The authentication is the same process in the CNS. But how? So? The G S GSM will take the MZ. And change it to a global title so it can know to which HLR it can be centered. Here, the SDS. And once it knows the HLR, it will send a send authentication info message and requests the triplets. And what are the parameters inside the authentication info? Which is the type of value. So which the value is a, 0, 1 or 2. 0 comes from the MSC. One comes from the S, GSM, two comes from the IMS network node, which is DCF or CS. Now, he did sign of value is one. And the second parameter in descend authentication info is the IMSI of the subscriber. The Agile are will respond by sending authentication o'clock or response. And in this SCR or send authentication response, inside it is a signed response and a random number and a cipher key. How is how the GSM receive the sign response? There are the member and the cipher key. It will take the side response and ssh store it, MB and MB contexts or Mobility Management Contexts. And send user authentication info message to the user equipment and ask him his authentication parameters. So this user will take the random number and secret key and put it in the algorithm. And we'll get signed response number 2 and then send this side response to the FSGS. So now the FSGS and has assigned response coming from the HLR and another side response coming from the UE, which is the user equipment. And it will start comparing these two responses. If they are equal, then this person is authorized to access this level. If not equal, then it will send a message called authentication refused to the user equipment, stating that you can access this network. So let's see, once this user is successfully authorized to access this network, the SDS, and we'll start checking the equipment of this user. Checking the ME, is it blacklisting or what are realistic? And again, the ME is coming from the USGS n not the HLR. If this person is whiteness did the S GSM will oblique location to the subscriber and go to the HLR requesting upbeat location message. The same way in CS. And it takes the MZ and transforms it into a global type. And by global title to know which HLR shouldn't go to. Then send an update location message. And its purpose is to let the HLR store the FSGS and address. So if any future transactions or any downlink packets come to this user, DHL or will know which S GSM to direct this package 2. And in the same time it tells the HLR, please send me a copy of the subscriber profile. And in the upbeat location message, it will have the IMSI HLR address as JSON address. The location update type is he in, let's say initial attach or combined attach. This is all in the location message, which is sent from the USGS n to the HLR. The HLR will respond with insert subscriber data message. And its function is to start downloading the subscriber profile on the GSM. And the subscriber profile is stored on MM context, which is the mobility management context. What is the type of data that Agile or sense to as GSM? And the ISD or the insert subscriber data message. The MZ. The surface list. Does he have SMS service? Internet? All of these are services for borrowing information. Does this person have Internet barring or not? Can you access the internet or not? Roman restriction, restrictions such as the GPRS with the UMTS or LTS subscription data is person, prepaid and postpaid subscriber. All of this is within the profile sent to the S GSM in the subscriber data message. After the USGS N receives the profile, it will send subscriber data acknowledge. Once the HLR send offers data, it sends update acknowledge message to the S GSM. And FAD as GSM, takes the information of the subscriber and it will store the subscriber profile and the mobility management context table. And this table is in the SDSS. Then the GSM sends, accept, attach, use your equipment and allocates the TMZ from the subscriber. And when you send messages again by the air interface, introduce yourself with the TMZ only. Then the UAE response with attach complete and will send by TMZ that you actually allocated. So this is the basic attach procedures for it. Now, let's go to another part. Now. What is the attach procedures? If UE is not perched? Perched means a mobile subscriber that is unreachable or detached. So I give a feature inside the GSM to not delete the mobility management of this press. I can wait a day or two. But after a day or two, and this user still unreachable, no, I'll actually delete information. So this person will move from detached to perch, which means I have no data. So the attached procedures will happen here if the user equipment is not perfect. So it's profile is still stored on the SG SM. So purge means that this person data is still on the SDS n and when deleted. But he had touched. Anyway, but so he can access the network and he must attach. But attachments for the first time. And attachments, As gs m knows about him, as he is still not purged, has different ways. In other words, it's much easier. Here the user equipment will send the attached request to the FSGS m. But the Attach Request here, I will send it by the TMZ. And we'll also send the last routing area. He was him before he got attached or detached. But here the SES and still has the user equipment context of the subscriber. And in the same time also has the authentication parameters also stored in the mobility management context. So the S GSM will do a local authentication to the subscriber. It doesn't need to send a send authentication info message to the HLR as it already has the authentication parameters. And after the SDS and finishes the authentication process internally, it still doesn't need to update location with HLR because I still have the user profile of this subscriber and I didn't delete it. The upbeat location is for the HLR to confirm with SDS and the SDS and address the SDS M to take the subscriber profile from HLR. And since this person is not purged, so the mobility management context is still available in the S GSM. So he's not purge and the HLR stored in the FSGS, stored the FSGS and address that controls this subscriber is the is the FSGS. And so I don't need to update location with HLR. Hereafter the SES and finishes the authentication. I will send an attach Accept message with the new TMZ assigned to this user. And the user will respond by attached complete. And this is in case of user equipment not perched. What if the as GSM changed and this person detached and return back active or went to a place with coverage area and became reachable, or went through a new as JSON area. So it changed the GSR. Now what happens is the user will send attached requests to the new USGS. And the identification I magnetic piles in this new request is the TMZ and also the old bombing area identity. So I will have the new FSGS and received the attached requests from a subscriber by the TMZ, the new USGS, and we'll know the old STS. But here, the new USGS and doesn't have the subscriber profile nor the authentication parameters. So it will authenticate the subscribers by the, by the MC. And the most important part in the core network is the MZ. So the new as GSM will send identification request to the old FSGS and asking for the IMSI of the subscriber. And in the same time asked for the authentication parameters as well. Here, the old STS and will respond with identification response. And in this identification response is the MZ and authentication parameters of the subscriber. So the new USGS n now has the MC and authentication parameters and now can do local authentication to the subscriber without going to the HLR. Let's imagine that the new S GSM failed to retrieve the identification from the old as GSM and couldn't get neither the MZ nor the authentication primers. So here the new S GSM will send a send identity requests to the UAE. And the reason of this request is to get the IMSI of the subscriber. Here the UE will send some identity, identity response and reply with the IMSI, the new edges. And we'll study in normal procedures or the process of the attach in which it sends, I send authentication info to her cello and Atul our response with some other authentication in Fort knowledge. And it took the sine response, agile or Ben takes sign response from user equipment and compared the two responses. And if the two are equal, this person can access the network and start checking the Emmy of the subscriber as Emmy is sent from new SES n naught HLR. And after the equipment check, the GSM will send a big location message to HLR and states to HLR that it serves the subscriber or the subscribers rate already attached to it. But what if the HLR found that the user was attached on a completely different as GSM and an USGS and stated that this person is attach it on me. So the HLR will cancel the old location. So here the HLR instructs the old as GSM to delete any context for the subscriber. As this person is no longer with you, the audience GSM will send canceled location acknowledged after HLR canceled location with the old as GSM. So it continues the normal scenario on which it sends insert subscriber data, which is the user profile of the subscriber. So the USGS and the other response with insert subscriber data acknowledged until it finishes sending. On the HLR, the HLR sense of location acknowledge message. So here the new S GSM knows it took up data. So it sends then you TMZ to allocate it to user equipment or the subscriber. Here using the equipment will reply with attach, complete. And thus, at far as we go for this work.
14. PS Packet Core Procedures Part:2: Hi guys. Now, the last time, in the last session, we started talking about the attach procedures. In other words, how the user attaches to the packet switching core network. Let's now talk about the combined touch. So if a user wants to make a combined attach on the CNS and PNS network. So this user wants to make that assertions and voice calls. So this person is on 2-AG or three G and wants to make surfaces, whether voice calls, SMS, browsing on the internet. So this person will attach on the network by the MSC and on the ps network by SG, SM and the packet switching know. So this user can make voice calls and data sessions. So we can do the voice calls. He has to do the MZ attach on the circuit switching networks. And we explain this in the circuit switching part. So he can do that assertions. He has to do a GPRS attach on the packet switching network. So this user can do the combined attach. There has to be an interface configured between the FSGS n and the MSC. So the S GSM must connect MSC by and or by the interface called the GFS interface. Now, the function of this GFS interface will allow this person to attach on the ps and from the PS attached to the CS, which is the circuit switching never, always happens by the GFS interface, which is between the S, GSM and MSC. So if this person made a combined a touch on the CS network and PS network. And of course the attached on the SGA stem and on the attached on the MSC. So this means that this MSC, after it finishes the user attach on the network, this MSC will register that this person in the packet switching is attached on this specific FSGS them. And the SG SM will register that this person on the circuit and the circuit switching network is on this specific MAC address. So the S GSM will register the MAC address, and the MSC will register the S gs n adders. Now, let's see the procedures that happen during the combined the couch. They're actually very close. What we explained in the last session. Here, we will presume that this person was attached on the network and then detached and attached once again. So he changed the S GSM. So he attaches on a new as GSM rather than the old as GSM and detached from it as well. So he opened his phone once again, but on a different as GSM. So when he opened his mobile once again, he sends and attach requests to the GSM. This Attach Request has an attached type. In this case is a combined the touch. Which means this person or the mobile equipment that he is holding supports him to make voice calls. And in the same time that assertions. Alright. So in this case, the person attaches by using the TMZ. Why TMZ? Because simply, this is not the first time he attaches. So smart and initial attach as he was attached before. And then closed his phone. So he detached and then opened his phone again. So he wants to attach once again. So this new as GSM receive the TMZ, which is the attached requests, and the identifier of the user, which is the Kimsey, as the user is introducing to this TMZ. Or sorry, the users actually introducing himself to the stimulus. Now, before the FSGS m does anything, it needs to know the IMSI of the subscriber as it wants to know who you are and get the authentication parameters or the Mobility Management Contexts of this person. It will know by the old as GSM before this person closed his book. So I will send an identification requests and I is referred to the new as GSM, which will send an identification requests to the old GSM. And in this identification requests, I will ask to send the authentication parameters and the IMSI of the subscriber. The old as GSM, will take the old authentication parameters and MC and send it to the new USGS M. In case the new SES M doesn't have the authentication parameters on an EMC from the old S GSM or any problem happened. It will send an identity requests to the user equipment and we'll ask for its MZ. Yes. You did identify yourself to TMZ, but the TMZ is not enough to send me your Mz. That's the scenario that we're cure in this case. All right. So in this case, the user will respond with the MZ. So then you as GSM received the EMC from the subscriber. The GSM will need to authenticate the subscriber to know if he is authorized to access this network or not. So again, the SDS and will need to authenticate the subscriber to know if he's authorized to access this network are not authorized to access enough. So it will send, send, authentication info message to the HLR. And we'll ask for authentication parameters for the subscriber. So the actual or will send the site response and cipher key and random number to the new S GSM. So the new as GSM will take the sign response and we'll keep the sign response and send the send authentication info to the user equipment. So it can send the sign response from the users act and from the sender authentication. Authentication. I apologize in for technologists one. So let me refresh that part again. The newest GSM will take the sign response and we'll keep this side response and send the send authentication info to the user equipment. So it can send the sign response from the user. From the sense of identification in foreknowledge part. So the new FSGS and has assigned response from the network and another side response from the user equipment. And then it will check if they are both equal or not. If they are equal, then this person is authorized to access them. And if not, what happens in this case? If they're not equal, then I will return with a message to the user equipment until it, the authentication refused as you are not authorized to access my network. Okay. So in case that this person is authorized to access the network, normally, the new S GSM will send a check ME to the EIR. And the check ME is used to check on the Mobile itself. Is it stolen or has any problems in which the ME is the identifier of the mobile equipment. As every single mobile has its imine. If the EIR response that this is blacklisted, then I will blot the subscriber to access. And if white-listed, allow him simply to access as well. Now, the new USGS and needs to send an update location request to the HLR. So it can tell the HLR that this person now is registered on the SDS. N will tell the LR, please register the FSGS and address of this user. Then the HLR uses this FSGS and address if this person receives any downlink packets. So the actual r will know that these packets are going to this user, which is available on this specific as GSM. As all this data is newly registered on the HLR or sorry, is now registered on the HLR. From the things that the SDS n does in the update location requests. It asks the HLR a copy of the subscriber profile. Once the HLR receives the update location requests, it starts to send cancel location to the old FSGS 10. So the HLR will detect that this person was registered An old as GSM. So it will send canceled location to the old as GSM. And we'll delete the mobility management context and PDP contexts of the subscriber. And then it will send cancel location, acknowledge message to the HLR, confirming that it deleted this person from its side. Now, once this process is complete, the HLR will send, insert subscriber data to the S GSM. And we'll send or load or upload the profile of the subscriber on the new as GSM by the insert subscriber data message. During the HLR or while it's sending the insert subscriber data. And it's uploading the data or profile of the subscriber on the new USGS m ds, GSM will keep saying continue because I'm receiving your data, whether the EMC EMI, the routing area, for example, or any other words, the profile of the subscriber. The GSM, will respond that it acknowledges that it is receiving till the HLR finishing finishes the uploading process of the subscriber on the SGC. Then it will send update, location acknowledged message. Now, the subscribers attached on the S GSM, this person wants to attach on the CS, NPS, which are the circuit switching and packet switching on or on the same time. So the S GSM will send an update location requests to the MSC by the GFS interface, which is between, as we explained before, the SDS n and the NSC. Then MSC, sense update location to HLR and takes the ISD, which is short for the insert subscriber data. And registers on the CBS Network on this MSCR. So HLR registers in case of the CSS network is on this specific MC, MSC. Now, once it is done with uploading this profile, the Agile or will send update, vocation acknowledge, and the MSC will send to the FSGS n that it finished or accepted the update location from its end. Here, the S GSM will send, Attach, Accept to use your equipment. And in it will be the P TMZ. So the FSGS n will send, Attach, Accept, message and NDP TMZ and allocated TMZ in any future transactions for the subscriber that you will send to me only through TMZ and nothing else. Here. They use your equipment, will receive the message and respond with attached complete. Okay, So now we understand that part. Let's go to another part. Now here, we're going to be talking about the detach procedures for what? The user equipment will receive the message and respond with a touch complete in the first slide. But let's talk about the detached for one. Now so that we understand. Or let's say we can use the combined attached process or signaling. In the combined attach. We have another thing called detach. Let's see the procedures that happened during the detach process. So now you as a user, when you close your phone, C are considered detaching or removing yourself from the network. And you will send to the network that you are no longer on this packet or on the packet switching. And I will not be using this FSGS 10 service again, nor will I browse again as I'm detach. So I don't need to be registered. The user may ask this request of the network itself. The network itself may ask the subscriber to detach. So refreshing that again, the user may ask their posture detach. Or the network itself asked the subscriber to detach. So this detach may be requested from user equipment or requested from us GSM, or even requested from the HLR. Let me ask you a question. When does the edge of our requests to detach the subscriber, remove it? Simply. It happens when the user does routing Area Update. So he changes from As gs n to a new as GSM. So in this case, the HL or sends cancel location to the old GSM. And this means that this person is detaching from the oldest GSM. Now, there's another thing that this HLR gets. It gets the user profile from the billing system. Like let's say for example, an example, small example like CBOT, for example, from the customer cares. Because when you buy a SIM card, you put your data with customer care and subscribe, let's say to a specific package for the customer. So you create your own data. So the HLR knows it already from the billing system. All right. Okay. What if you changed something within your profile from the customer care and there's a link between HLR and billing system. So let's presume you change in your profile, anything like your package or your Mz as you swapped, maybe your SIM card. So this data will be reflected on HLR from customer service. So how will the HLR reflect this data on the yes. Gsm? That's a very important question here. Let me explain this simply. Let's say you're attached on the network and you are on a specific As gs, then you change in your profile, whether the MZ, the subscription or whatever. This may be. The HLR wants to notify the FSGS n with this new information. So the HLR where we will actually request that you detach from the SDS n. So the S GSM can reattach once again. And when you reattach, once again, the S GSM will take a copy of the subscriber profile. But the last updated copy of that last updated version you actually did. So this is the SLR and this is when it requests the detach. But When does the S JSON request the details? This is another important questions as well. Sometimes the GSM may suffer from lack of resources and it can't give any resources to its subscribers. As, let's say there's high utilization that happened, just opens and the S GSM is in a problem and it can provide any resources to its subscribers. So they can do data sessions. For the can't actually do data such as, for example, or browsing or whatever. So the GSM detaches the subscriber. So this person can attach to another as GSM in which the utilization on it is actually a bit less. So let's rephrase this a little bit more again. If there's high utilization that happened all at once with the as GSM. So the SDS and can provide any resources the the subscriber needs to do or browsing. So the SES GASGAS n missile attacks to subscriber. So this person attaches to another as GSM, where the utilization is a bit less. Okay? There's another case. As, let's say, if you're an engineer and you're sitting doing some tests and your requests, or BY command, you detach the subscriber from the from this SPSS. So this person can register, register himself on in you as GSM. So the detach request is coming from the USGS and also, alright, now, let's talk a bit or let's see the detach requests or procedures when the mobile is initiating the detach process. So how will the signaling flow happen? If I close the mobile, for example, or remove the SIM card. So the mobile station is initiating the discussion posts. First thing, the mobile station or use your equipment will send a detach request to the S GSM. But in this detached requests, we will have the TMZ of a subscriber and be touch-type. And does he want GPRS detach combined Beta? So does the user want to remove himself from packet switching only or pocket and circuit switching together. The SGX n then deletes the PDP contexts and mobility management context of this user from the S GSM and sends to the G GSM. And also ask it to delete the PDP context of the subscriber. When DDGS n deletes the context of the subscriber, it will reply to the gs n with the lead Pb IEP contexts response in case this detach request is a combined detach. So this person, once a detach from CS, NPS, and MSC with SAS EM as well. Here, the SDS and Wilson to requests. So the as JSON central requests if this person wants to detach from CNS and PNS and MSE with S GSM. What are the two requests that will be sending? The first request will be the TMZ detach indication. The second requests will be the GPRS detach indication. The TMZ detached indication. Here. The S GSM informs the mobile NSC to start. The detach from the C has no. The second one we talked about, which is the GPRS detach indication. Here, the MSC is told by the GSM that this person is detached from my end. So please delete or remove the configuration of the subscriber from the GI S interface between us. Because this person. Not on the ps network anymore. Now once this process ends here, the S GSM will send, detach, accept to the user equipment. And in the same time, the FSGS and more thought releasing radio channels. Now, what is one of the radio channels used for? The radio channels were actually reserved for this user. In this case, when the user equipment initiated the detach process. So what if the GSM decided to detach the subscriber? What is the signaling process that happens here? We said the GSM can detach if it has high utilization. So it can put this user on another as GSM with lower utilization. Or can put this user on another S GSM again with low utilization or let me rephrase that part. Let's see, as an engineer, he can be attached to subscriber himself. So there are two cases, the SDS and can attach itself when it has high utilization and put it on another as JSON with low utilization only said, it happens manual when the core engineer candidate subscriber himself. So in both cases, the S GSM will send the detachable. In case as GSM will send detached requests to the user equipment or the subscriber to make him attach on a USGS n. The detach request is written in a very specific way. In case this is a GPRS detached, which is detached from the network only, not on CS. Here, the USGS n will send to MSC GPRS detach indication. I will ask it, please erase the configuration of this person from the GFS interface as this person is attached to CS only and not on CSI nps till he attaches once again a new as GSM. Here the user equipment will send, detach, accept, and in the same time, the radio channels reserved to the subscriber will be released. Now, in case of HLR initiated detach, in which the HLR sense detach in case if the profile of the subscriber change from the billing. So I need to change this profile on the FSGS m, So I can send to the FSGS and to detach this subscriber. And when he attaches again, I can send you this profile or the last updated profile. Or in case the user moved from one area to another as JSON and did eroding area. So the HLR needs to send canceled location to the old as GSM. So it's the same process. But the HLR will send canceled location to S GSM. Now, those were the cases of detach. So I hope you guys understood the detach procedures. Now, let's go to something a bit different. We have something called the perch. So after the user equipment detaches from the GSM, the SG ASN has two options, either to leave the user data, which is the Mobility Management Contexts, and PDP contexts of the profile are not delete it as not deleted one once, all at once. And just wait for 23 days, or just delete this oldest data organs. So these are the two options, either to wait one or two days, or two or three days. Another way, the context of the profile, or you can delete it all at once. So this depends on the network configuration or what I can figure on the SG SM. Now, here's a question. Why do I leave the option of not erasing the subscriber data, let's say for two days for example. So I can actually save signal. So instead of this person opening his phone tomorrow and do everything from the story, whether going to HLR and receiving authentication than a bit location. No. I'll save all the signaling and leave this context on S GSM for two days, for example. So in this case, the S GSM still has the authentication primaries, which is the mobility management context. So sorry, this, in this case, the GSM still have authentication parameters in the mobility management complex. So the SDS and will not need to go to the actual law so it can authenticate the subscriber. So here what it did was that I saved signaling from the center. Now, the S GSM will still have the mobility management context, and the HLR will still save the SG SNS. So the SDS n will not need to go again to HLR to make update location process. Why? Because this person is already available on the SDS n and his profile is on as GSM and as JSON address is saved on HLR. So I don't need to go to a new location update with the HLR. Now, the signaling part as signaling. So today's past and this person didn't open. You will find the FSGS n sending the HLR purge mobile station. So the SDS and we'll send the context of the subscriber and delete and sends to HLR stating that this person is no longer with me. So please delete it. So the HLR, We'll send purge, mobile state acknowledged. All right, Now here let's see the PvP contexts activation signaling procedures. Let's revise the PDP first. End-user so he can send or receive sessions with the external packet data network or Internet. He needs to do two things. First, he needs to attach to the network. And after he attaches, he needs to do a PDP contexts or PDP contexts activation procedure. The use of this PDP is that when he sends the packets of data on this PDP, which is between the user equipment. So the GSM. So this is the pass or tunnel that the user sends or receives his packets from the internet, for example. Now, inside this PDP, myself as a network, I describe how your packets. So the packets will come from which API. So are these packets going to IMS network or Internet network? Depending on which APN you are on. And this is found in the PDP contexts. And we'll also have your IP address, which you are on the internet with. And quality of service. And which UCI you, you're actually on as well. Which means your quality of service flow of bit rates, or how much delay you'll be getting all your packet loss. Or how many packet loss for a million packets can you actually lose? All of these are described on the quality of service on this PDP contexts. So here, as we said, that any PDP is associated with a specific APM. Now, what is APN? It is the axis point mean, which is a logical name for any PDM. So let's say I have a PDM as the Internet. And this Internet APM is hosted on the GSR. And I haven't IMS network, which has an IMS APM hosted also on the GCS. And me as a user, I want to browse or open a session or send a packet of data with the iterative. So I will open a PDP contexts to the, to the internet VPN. Now, each APN has an IP address range or pool of IP addresses. The user, so he can access the Internet. For example. He has to go to the Internet APN and take an IP address from the Internet APM and go to the Internet using this IP. And this IP address is found in the PvP contexts. Okay? Now, let's see the procedures or signal in the PDB contexts activation. First thing. The user's sense. Activate PDB contexts requests to the GSM and indicates that he wants to open a PDP. And says in this PDP contexts, I want to connect to the Internet, for example. Because I want to do data sessions on the Internet. And the user says, I want quality of service for this PDB contexts. And all this is available in the activate PvP contexts requests. Now, what is the most important parameter? In the activated PDP contexts requests? The most important parameter in the activated PDP context requests is the APN, which the user wants to connect on the FSGS n. Once it receives the activate PDP contexts requests, it will revise or validate this request and even validate this person accessing the Internet. Is this subscriber? Is he actually allowed to access the Internet or not? Is he allowed to access IMS or not? Is the quality of service he is asking for more than what he can use or not. All these are some negotiations or validation from the FSGS n to the requested data the user asked. Now, the S GSM completed its validation. What happens next? It, now it needs to open, create PDP contexts requests to the GGAC. The same time. It doesn't know which gigi, S and goat. As we said, I have more than one, G, G, S, M. But which one would I go to? The GSM requires the DNS, which is the domain name or the domain, domain name server. And inside the request of the activate PDP contexts, there will be a domain name of the EPM that you want to connect on. Like first small example here. And just, it's just a small example. Martingales Internet dot Vodafone, EEG, for example. So the S GSM will take the domain name of this APM and sends it to the DNS and asks to know the IP address of the GSM. That this API. So it actually works as a beacon, say resolver here. So it takes the domain name to an IP address and returns it to the GSM. Now, the S GSM knows go to which GSM, and then it sends it. I create PDP contexts requests and ask it to open and PDP contexts for this huge. But in this request, you'll find the APN, the quality of service that is supposed to be assigned to the subscriber. After that, the GSM validated. It. Also does static IP address, which is on the user profile as the S GSM, gets the static IP address, what it was doing, the insert subscriber data from the HLR when this person was attached. And also sent the PDP type, let's say x, as this person may be IP version 4, and also inside it s GSM tunnel endpoint ID. Why does this happen? So we can open the GTP tunnel between BSG S, N and G GSM. So the GTP tunnel opens the GSM and must note that as JSON endpoint ID and the SDS n must know the tunnel endpoint ID of GSM. So again, the GTP tunnel opens in the gigi S N must know the FSGS n endpoint ID, and the SG ASN must know that tunnel endpoint ID, VGS. They have to know each other's endpoints, IB, in other words, on very briefly, all this data. Where is it found? It's found in the create data PDP contexts requests. Now here, the g, G, S, M already received the create PDP contexts requests. And the GSM will start to communicate with the PCRF, which is the policy and charging rows function. So it can take from it the PCC rules and RPM and makes sure about the quality of service that it will give to the subsequent. Now, the PCC rules are like if a subscriber, let's say gets on the WhatsApp and the WhatsApp traffic is on his re-plan is free of charge. And on Twitter, he is charged half-price. And if downloading, I'll do throttling on the bit rate of the subscriber instead of him being on when, let's say one megabit per second, I'll let it be 512 kilobytes per second. All of these RPC rules the GSM must do on the service data flows or the packets coming from misuse. These PCC rules, the GDS n gets it from the PCRF, which is the policy and charging rules punch. The protocol between n and PCRF is called Diameter protocol. The type of messages that flow on the Diameter protocol are called credit control messages or CC messages. Now, what are the types that I have? How many types and what are they? I have three types of CC messages, which is the credit control messages. First one is the credit control during the PvP contexts creation, which is short for CCI. Second one is the credit control during the PvP contexts, live and sending packets, which is credit control of the messages, which is short for CCU. Third one is the credit control during the detach or deactivation, which is called credit control. Termination message is short for CCT. Now, in this case, I'm activating the PDP contexts. So the type of credit control messages is the initiation. So the GSM will send credit control requests, initiate to PCRF and tells PCRF that it wants to open a session. And in the same time, send me PCC rules and RPN, which I should be applying on the subscriber. And in the same time, it also asks to sell me the quality of service. The PCRF will receive the requests of the GSM and reply with credit control xA message. Again, the PCRF will receive the requests of G, G, S, M, and reply with credit control, accept message. Putting the PCC rules that should be applied on the subscriber or the rpm, and the quality of service that also should be applied on this user. Now, let's say, or the GSM found this subscriber is a prepaid subscriber. So this subscriber needs to be charged, Obama. And now we're like charging, for example. What happens in this case? The G, GSM needs to connect to the OCS, which is the online charging system. One. So it can charge the subscriber life. The protocol between G GSM and OCS is also called the Diameter protocol. So the GSM will go to the OCS and send credit control requests, initiate message to be OCS. So I can open a session with it and tell that the user is opening a PDP contexts and is now live. And we'll start sending packets of data. And in the same time, I will put the MZ of the subscriber as an identifier for this substrate. Here, the OCS will confirm the requests by Credit, control except message. And now the session is open and this person can start doing his session. We will also say how OCS works during live PDP. So this person is sending IP packets are packets of data with the OCS. And we will see how the OCS deals with this person as well. But let us finish the part of the PDB context activation first. Let's go back to the DSM. The DSM will start to assign data on the PDP context. I'll start to activate the PDP contexts. And we'll put quality of service and put the static PvP address that it took from the GSM as static. The sent by create PvP complex the process. And will also sign I dynamic IP address, which I already took from the internet APM, which this person accesses the internet with, which is the PDP hours, added the same time. The GDS and puts the TGS n endpoint tunnel ID, which moves it to the GSM. So I can create a GTP tunnel between the two nodes, between the S GSM and the GSM. In case of direct tunneling. The GDS and puts an extra piece info, which puts its GG as an address. So the S GSM can send it to the RNC. So the RNC knows that Gigi has an address and R and C will also send the RNC address to the GDS. So now I can create direct family between R and C and G GSM. Now, the S GSM received the activate PvP contexts request with our contexts response. And now we'll open or reserve radio channels with the RNC and send something called the Rab assignment requests. And RNC will start reserving radio channels and some RAB assignment response. But the RNC might send the S GSM and tell it that this quality of service is too high. As now, I'm highly utilized. So I can give you quality of service you're asking for. So please just downgrade of it. So the S GSM will send a PDP contexts request with the negotiating quality of service to G GSM. So the GG SM will approve this new quality of service and then update PDB convex and send update PDP context response, and put the new quality of service in it. Or audits. And at the end, the GSM will send activation of PDP contexts accept. So now the PDB is open and the user can now send or receive the pockets of data with the Internet. Normally. Now, we come to the PvP tax modification. So if I'm doing a modification on this PDP contexts, when can I request this PDP modification? Well, any network in between or in C or GSM, or as GSM may have high utilization. So I need to decrease the quality of service that I opened for this person. So I need to modify. This PDB convex or downgrade this quality of service. So I need to change. The PDB contacts were modified as signaling. How does this even happen? Let's go through this part. Due, which is the user equipment. Sense. Modify PvP contexts, request, which has that changed parameters, either downgrade quality of service or anything else. So the S GSM, sense Update PDP requests. And Eliot, the update program, the updated parameters. And the GSM approves these updated parameters and then send updated contexts response to the USGS M. And here also happens, wrap modification with the new quality of service assigned to the subscriber between as GSM or in C and user equipment. And if the RNC asked to update the quality of service, it also sends the assignment response to the GSM and f ds GSM found there is an update in it. It sends the update PDP contexts request, and this is sent in case of update only. Then the GSM approve this update and sends the response. And lastly, modified PDP contexts excepts. Okay. Now, let's see what happens during an active session. So the user is attached on the neck. And in the same time opened a PDP convex. And he may be using Twitter or WhatsApp. So in this case, we will find in the RPN PCC rules on the subscriber that this person, if he's only using WhatsApp traffic, you will be put on reading room number ten. And reading new, reading room number ten states that this person is free of charge. If this person did Twitter traffic. So the traffic will be on waiting room number 20. And this group now free of charge. So if this person starts using Twitter traffic, so he sent PDP context, the GSM wants to know the type of traffic stream that passes by it. So it will get back to the DPI, which is the deep packet inspection. So it can analyze this truck. Ddgs M will work this traffic or mark dystrophic with reading group number 20. As it knows this from the DP. Here. The GSM will send the OCS, which is the online charging system control request message, which is U, or update message. But during PDP contexts creation, it was initiated, but here it is updated. So let's rephrase this part again. The DSM, we'll send the OCS, which is the online charging system acquitted control request message, which is an upbeat message for the year. But during PDB contexts creation, it was initiated. But here it's opposite. So the GSM will send the OCS a credit control request message stating that it has traffic from a reading group number 20. And we'll ask the OCS to allow this traffic or not. Here, the OCS will start with looking at the use your balance, and then we'll assign a certain quota and assign it to the GSM. So as an example, it will take a 100 Mega and send it to G, G S, M. And a message called credit control, except message of the and stating that this person can use a 100 mega on Twitter track. Here, the GSM will allow twitter traffic to pass until the consumption of the a 100 minutes. And after this assigned quota is done, the GG SM will send credit control requests of the message to the OCS and request from a another poder for the subscriber. Now, the OCS will start looking at the user bonds. And we'll find that this user has mobile. So it will reply back with an error code called credit limit reached. And after the GSM receives this credit limit reached message, it will start dropping the Twitter traffic of the subscriber. Here, the subscriber decided to start using Watson. And these WhatsApp messages are on reading group number 10. So therefore, when these WhatsApp messages are sent, GS M starts analyzing the traffic. And we'll go to the DPI and ask what this traffic targets. So so the DPI will respond that this WhatsApp that sorts, the DPI will respond that this is what's, so GSM will put the data flows of this WhatsApp on winning group number 10. As the RPM told it to. Then it will send credit control upbeat message to the OCS and repost a quote for winning group number 10. Now in this case, the OCS will reply with credit control except message. And put just like you can say, an imaginary quote or quota that we'll never finish. And state to GDS and that this person can use a 100 meters on this WhatsApp, although there will be no consumption Anyway. As, as we agreed, that this is just an imaginary quarter. Let's put here the GSM. Once it receives the credit control except message, it will start passing the user traffic to WhatsApp group or reading group number 10. So this user can do WhatsApp traffic, but at the same time, tend to Twitter traffic. Now, what happens during PDP contexts? Deactivation? Of course, the PDP contexts comes after the user detaches from the null. If the user will initiate a PDP contexts deactivation, he sends a message called deactivate PDP context requests to the FSGS. Then the S GSM starts deleting the PDB contexts from its end. As we said, when the PDP context is created or from active or created of activity B as JSON and JSON and use your equipment, create a PDP contexts in themselves. So the GSM will delete the PDB complex and we'll send delete PvP contexts requests to the GGC. So the GDS n can send the PDP contexts from itself. And the GSM must do a termination, termination session between itself. The PCRF. So it sends a credit control requests type T, which is termination. So the PCRF response with credit control acceptance. Then the G GSM needs to make a termination session of the OCS by the credit control with us. And we'll get a reply back with control except message. Here. The GSM deletes the PDP contacts and sends to as GSM response of deletion to this PDP context. Here the SDS and sends delete or deactivate PDP Context Accept. And in the same time, it releases radio bearers assigned to the subscriber. So someone else can actually use. Now, we will go through something new called routing area of the it is like the location area update in the CBS Network in which this person moves from place to place. So he changes from the routing area he receives from. Once this person receives from his tower around in area ID, different from the army he has. So this person asks to do routing update with the map. Now, what are the rubbing Area Update types? I have the the Internet, the intercept, the intercept as GSM routing area of the so the user moves from as GSM coverage area to another as GSM area. The second type is called the intro S GSM, in which the user moves from routing area to another routing area, but within the same as GSM coverage here. So I don't move from one edge GSM to a new SDS. The third type is called rats, is routing area of technology. This is when the user moves from a to G as GSM or coverage area of a two G network to a coverage area of 3D network. So he changed the technology and vice versa as well from 3D to 2D. So here the technology's changed. Any group of cell or cells form a rounding error. But any, any group of routing areas for allocation area. Now, let's see the rounding area of the signaling procedures. Here, the user moves from one routing area to another. So we will find the routing area he received from the PDS or node P is different from the old one. So we will request doing a routing Area Update. So the user will send a routing area of the request message to the S GSM. And in this message is the flimsy new and old rubbing area ID and BSC or RNC address that he is on. So the user will send a routing area of the request message to the FSGS n. And in this message is the TMZ, new and old rubbing area ID, BSC or RNC address that Huizong. Now, the GSM will start using the same process we explained before as the S GSM. We'll ask the SDS and contexts from the old SAS EM. So the GSM will send the mobility management context and the PDP contexts. Then it will authenticate the subscriber vocally, as it doesn't need to go to the HLR to authenticate His subscribed. What if it couldn't get the data from the old SDS? So here, the S GSM will send a send identity requests to the user, put me, and ask for the MC. And start doing the process all over again. So this send it the SDS and context response. So we started doing authentication for the subscriber. Then the S GSM will confirm or acknowledge that it received the mobility management context and the context of the subscriber. So if the user or subscriber has downlink, downlink packets he received during doing routing Area Update and came on the old as GSA. And these packets of data are maybe Whatsapp masters or identification that is sent to this huge. And it will go to the old STS. And once the new as GSM, since the SDS and contexts acknowledge the old as GSM sends forward packets. And inside it are all the packets that come to this person. So the new as GSM can deliver it to the user equipment. Here. The new as GSM sends update PDP context to the GSM, which has the new FSGS n tunnel endpoint ID. So it can open the GTP tunnel between it and the GDS and also has the negotiated quality of service. Why? Because the ACSM is now new as we changed the S GSM. So the S GSM may have new requirements depending on the load on the STASS. Here, the GSM, We'll send u
15. PS Packet Core Key Features: So these are the features of the packet switching. Let's talk about them. Okay? The first thing is the SG ASN, top. So the FSGS and pull is like the MSC poor. There is absolutely no difference. Normally, if the SG S, N, if it's not in a pool, it serves a specific area. And the other GSS GSM serves another specific area. And the third, as GSM serves another specific area. But if all three are in one pool, so this area, It's subscribers, instead of them having an option to connect this FSGS and, or to connect to this as gs. And only then, no, they can actually connect to all or on all three FSGS, ns. So that's the idea of the FSGS and poor. And the same idea is in Paul 2 and tall three. Every pool of SG, ASNs can all serve any subscriber under the area of any of these SGAs adds. Now, the benefits of FSGS and pull. The first thing is balancing or sort of load balancing. So for example, if the SES n has a million subscribers under it and the other only other FSGS ends only have a 100 thousand users only. So instead of these million overloading this specific SDS, and I can actually distribute these million on the other two as GSM. So the idea is load sharing or load balancing. And also in redundancy. For example, if let's say there is no pooling and this FSGS and had a problem and drop. So in this case, the a 100 thousand on connected are actually, let's refresh the part when we said it dropped. So in this case, the a 100 thousand can actually connect to any S GSM. But in case of pulling, the 100000 can connect to the other SDSS. So this is called redundancy. There is an important factor and the FSGS n, which is the NRI, which is the Network Resource Identifier. Any FSGS n inside a pool is recognized by an IRR as the NRI differentiates each SGA scan, the MRI part of the TMZ, as we said in the last part of the attached procedures, the FSGS and allocates a TMZ to a subscriber. And when you send to me, you sent to me using this TMZ and not using the IMSI. Inside the TMZ. There is a part for the NRI. This part of NRI defines on which GSM this person is on. Gsm one, for example. Okay. And the NRI makes a difference with me as when this person makes a future transaction, he will send to the RNC and BSC. This request will be with the TMZ. The BAC and r and z are all connected. So if I have, let's say here, ten bs, Cs, the 10 will be connected to all three as GANs. So orange, sorry, all three GSAs. So every BSC will be connected on all three. The BSC will direct you to which as GSM, you suddenly requests, you want to do a service request and you said it would be TMZ. So which as GSM should I send you on? So the BSC, we'll look on your TMZ as it will look on the NRI value. And we'll find the NRI value saying that this TMZ is for SDS and number one, or number two or number three. So the NRI value configures this request is going to which SGA asset. So now I have two types of charging and charging and off-white watching. Off when charging doesn't affect the data session in real-time, which means that there is nothing called that they use. Your balance is depleted or finished during during a session. No. You charge this user after he finishes his session. You come by the end of the month and start collecting bills for this person and tell them this is your multicore. As he made the packet session or packets sessions for this X amount of money, for example, offline charging accused by the charging gateway. And this happens as the GSM stays on the session of the postpaid subscriber. So who does the offline charge? The RD postpaid subscribers. So the SDS ends up generating something called CDRs, which gives the cold detailed records. But in these CDRs, they contain the amount of traffic consumed and time of that assumptions. So as long as the subscriber is doing that associates, the FSGS n keeps generating CDRs. And the SG ASNs send the CDRs to the charging gateway. And the charging gateways send these CDRs to the billing system so it can charge this person at the end of them. Now, all my charge, I charge the subscriber on the real time, which means this person has a user balance or credit, and it is balanced. The pizza finishes during the session, I will drop or stop the session. The online charging happens by the OCS, which is the online charging system. And this happens when the GDS and communicates with the OCS. As long as the session is act. As we said. The same way with live PDP contexts. And we'll keep saying to OCS how the consumption of this usurious till the OCS informs the SDS n, then this person has no bounds. So please drop is traffic or stock has dropped. So this is the difference between online charging and charging. Now, what are the charging models that we have? The volume-based charging model, the time-based charging model, and the event-based charging. More. Volume charging is charging per how many megaspore, good as you actually by Zeus. Other networks charged by how much time session took, and this is the time base charge. The last one is the event-based charge. So it means how many times did you did how many times you do a certain action or certain event as how many times did you let say sent an MMS, which is the Multimedia Message Service, which are like messages that have or contain video or pictures. It's an old thing that was used actually, but it's still used at the moment. There is also a flow-based charging in which I charged the subscriber depending on the service heroes. For example, he does he want that perfect. So I make it pure charge. There's a Twitter is like for half the price. If maybe Facebook, then quarter or price. So all these, are, they charging models? And now we finish the packet switching. Thank you so much.
Amir Magdy, IMS/CS Technical Leader
