The TCP/IP protocol suite is the most popular method of communication across our modern Internet. In this video, you’ll learn about the TCP/IP suite and the layers used to describe the functionality of this model.
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The TCP/IP protocol suite is a model with four layers. We have an application layer, a transport layer, an internet layer, and a link layer. You may hear this referred to as the internet protocol suite. This is similar to the OSI model, but it’s obviously a lot simpler, and it fits a lot nicer with the way that TCP/IP operates. Because we only have four layers, it’s a bit easier to associate the functions of our applications and our networks back into this model, which makes it a little bit easier to understand.
The communication that applications use across our network is very compartmentalized. The applications communicate to applications. And they really have no idea what’s happening down at the network level. The network devices, of course, are sending traffic between point A and point B. And they generally also don’t know what happens to be inside of the application data. They’re simply sending it from one side of the network to the other.
So when we draw this out in the IP protocol suite, we can see applications talk to each other directly. The transport, or the UDP and TCP port numbers, talk to each other directly, but neither of them know anything about what’s happening down at the network level. Down at the internet and link level is where the communication is really occurring. The internet level being with our IP addresses, and the link level being the network communication itself.
So we have this protocol suite that starts at the application, goes down to the network. And as it’s traversing the network, the other devices only have to go up as high as the internet layer to see what the IP addresses might be, and then they send it onto its next stop. Finally at the end, we are able to put all of that data back together, and the applications are able to communicate with each other.
If we took some of the well known IP protocols and put them into the internet protocol suite, it would look something like this. Down at link level where we’re talking about basic network communication, we would have the ARP protocol. At the internet level, where we are dealing with IP addresses, we would have IPv4, IPv6, ICMP, and IGMP.
The transport layer is dealing with the TCP and UDP port numbers. And then everything at the application level will be the applications that write over these. If you’re going to do file transfers, it would be FTP. If you have a web server communication, it would be HTTP or HTTPs. Or if you’re transferring information via email, you might be using POP3 or IMAP4.