In this chapter, we will explain you the relation of devices and protocols with OSI model. That is very important to know if you are thinking about completing your Network Fundamentals Course successfully. Because there are many relations, we divided this lesson into two parts. There are twelve relations between protocols and devices and OSI model, and here, we will talk about the first five relations. Let’s see what are the commonly used protocols!
1.Point-to-point protocol (PPP). This protocol is always used when someone wants to create such network as TCP/IP, and especially when a purpose is to make it synchronous with the systems. What point-to-point protocol does? PPP is providing the connections for the host and to the network, or even sometimes between the rooters (when needed). PPP contains a security mechanism too, by having an ability to correct the errors, to compress etc, and can transport high-protocol datagrams all over the serial lines. When thinking about PPP, it would be the best to imagine it as a protocol used in telephone lines, or on the two end routers.
2.Serial Line Internet Protocol (SLIP). When talking about a SLIP, it is important to remember that it is actually a predecessor to a point-to-point protocol. It has an advanced version too, called CSLIP, and the C stands for the compression. What the compression does is that it reduces an overhead of a SLIP connection through sending only a header information (when that is possible), and in that case, it increases the packet throughput.
3.File Transfer Protocol (FTP). File Transfer Protocol can be best understood as a Client-Server Protocol. FTP is regularly used for moving the files between the different computers connected to the same network. FTP is also used for transferring the files from desktop and a server. Sometimes, File Transfer Protocol is making the ability for us to communicate with some other web servers (for example-download site). This protocol is definitely one of the oldest ones that exist. Besides all the functions we have mentioned, FTP also enables transferring texts and binary files and all that through a TCP connection. It has a strict mechanism of the restrictions (access and ownership), and that is exactly why it is perfect for transferring the files.
4.Telnet. When talking about Telnet, the first thing I would definitely like you to understand is that Telnet has a service which provides a remote logins capability. What the user has with that? The user that works on one computer has the ability to login to another computer. Both of the computers will act like they are in front of the remote machine itself.
5.Simple Mail Transfer Protocol (SMTP). SMTP is also a TCP/IP protocol and it has been used for so long for sending e-mail messages between the different servers. Of course, Simple Mail Transfer Protocol can be also used from sending a message to server from the client’s computer. It is important to remember that SMTP is most of the times implemented with a purpose to operate over the TCP port under number 25.