Hello friends, welcome to Engineering Panda family. From this video onwards, I'll be starting with new chapter based on transport layer in computer network lecture series. So in this video, I'll explain you how transport layer is functioning, as well as how many functionalities which is there with transport layer that I'll discuss in this video. In this chapter, all the functionalities that I'm going to explain you in great detail.
But first you need to understand how transport layer is placed in computer network and how it is working. So here you should know transport layer that is layer number four in OSI model that is a reference model for computer network as well as transport layer is layer number four in TCP IP model. Widely we are using TCP IP in computer network but reference model is OSI model.
So with both of this model layer number four will be transport layer. Let me show you how it is there. See when it comes to osi model in that we will be having seven layers right you can observe over here and in tcp ip model instead of these three layers we will be having application layer over here and after that we will be having transport layer so in osi model this layer number four that is transport layer now see how transport layer functions so transport layer will take input from station layer that is data so data will be input to this transport layer and it will perform segmentation and output will be segment.
So if you observe frame structure, if you observe frame structure, then in that you see here we are having MAC address of source and destination that we are adding at data link layer. If you observe here, IP address of source and destination is there that we are adding at network layer. And if you observe here, we are having segment that we are generating at transport layer. So input to transport layer will be data and output of transport layer that will be segment.
Right. Now what is segment? See here data will be raw data. That data may be mp3 data.
That data may be video data. That data may be image data. That data may be text data.
Right. That data could be anything. Means you can say here data size may be anything. It may be large data.
It may be small data. Now you want to communicate on. computer network so for that first of all you need to bisect data into small small chunks you see here we are having raw data so that data that we are bisecting into small segments now each segment that is assigned by sequence number as well as port number sequence number is just a numbering that explains you what is the order of this segment but this port number that is very essential that you should know see port number explains you for which process this data is there.
Let me explain you what is the meaning of it. See, for example, in your computer, if you open with Google Chrome, so in Google Chrome, whatever you are doing right now, that is having one process, which will be assigned with one port number. For example, in your computer, if you open up with Skype, then with Skype application, there is one process and with that, there is well defined port number so whatever process that is happening in your computer that will be having data and that data should be assigned by port number with respect to process so that process is identified over here based on port number over here so that port number that we added along with sequence number that gives you segment right so you will be having data which is input to this transport layer That data input could be given by station layer in OSI model and in TCP IP model.
Here there will be only one layer that is application layer that that application layer will generate data and it will give it to transport layer and transport layer will do segmentation over here. Right. So basic task of transport layer is to perform segmentation means it will be bisecting data into small small chunks where sequence number will be given and port number will be given. So I think now you are having idea about what is sequence number and what is port number. Right.
Now here if you observe, see how many tasks that is performed by transport layer. So transport layer performs segmentation. So I think now it is clear like how segmentation is done over here.
Right. But there are a few other things even that is happening like flow control. So flow control that is very essential mechanism that is happening.
Let me give you. one example that will give you more clarity like why flow control is required. For example, here we are having transmitter.
here we are having receiver this transmitter is transmitting data at 10 mbps speed but receiver can handle data with one mbps speed only so here as if transmitter is transmitting data with this speed then the receiver cannot handle it why the reason is receiver cannot handle more than one mbps speed so receiver will give feedback to transmitter and that feedback explains to receiver that you should lower down the transmission speed right there can be one more scenario Like as if I say transmitter is sending data with 1 Mbps speed, but receiver can handle speed up to 10 Mbps. So as if receiver is receiving 1 Mbps speed data, then receiver can give feedback to transmitter regarding you can increase the speed up to 10 Mbps. So here flow control that can be done with the use of transport layer. Right.
See error control mechanism that could be also done with the use of transport layer. See here in transport layer, usually we use. TCP and UDP.
About TCP and UDP, I have made one separate video, you just go through it, in which I have explained briefly how TCP and UDP is functioning in comparison, right? Here, in short, as if I want to say TCP protocol, then that is connection oriented protocol. Connection oriented protocol means what? Here, there will be flow control mechanism as well as error control mechanism.
How? See, error control that will happen by automatic repeat request for example as if receiver is receiving one frame and as if that frame is corrupted one then receiver will give feedback to transmitter regarding that frame was corrupted so you just resend that frame again to me so automatic repeat request that could be used for error control in next coming videos i'll explain you tcp and udp in great details but right now just consider flow control and error control that is happening a transport layer error control that we can handle by ARQ as well as with the use of checksum right see here process to process communication that is established by transport layer now what is the meaning of process to process communication see process to process communication means for example here there is one computer that is transmitter and here we are having second computer that is receiver now in receiver for example this is my computer in which there are three processes which is happening. One is happening in Google Chrome.
Second is happening in Skype and third is happening with Microsoft email outlook. Right. So the three processes are happening over here.
So all three processes are requesting data from different nodes. Right. So see that process handling that process handling.
that is happening at transport layer like transport layer will decide to which process this data should be forwarded like as i have told you see here we are having data so data is having segment number as well as port number so port number will say like for which process this data is there right and then to that process particular segment will be given and then after decapsulation you can have data and that data will appear in front of your screen Right. So here process to process communication establishment that we do it at transport layer. So in general, these four sections are very essential with transport layer. We will be discussing all four sections in very great detail in upcoming videos.
But first, I just wanted to have basic overview regarding transport layer. Even I have explained transport layer in OSI model. Still I thought I should give you brief idea about it. And still if anything that you like to share.
please note it down in the comment section. I'll be happy to help you. Thank you so much for watching this video.