Serial Line Internet Protocol (SLIP) is an older protocol that was used to connect computers over phone or serial lines. If you recall, the discussion on serial and parallel transmission, you will remember that computers have various serial ports. Well, two computers can be connected through their serial ports for simple serial communication. This serial connection can also occur over greater distance through a modem. When two computers link through modems, this creates the same type of serial connection as if the computers were connected through their serial ports [1].
A serial connection exists on the Physical Layer of the OSI model. As such there is no way to arrange the data for transmission. So engineers created SLIP to help arrange the data for serial transmission. This was an informal protocol that for a while became the de facto standard for serial transmission, but it was never adopted as a true TCP/IP protocol. In fact, when the Internet Engineering Task Force (IETF) finally described it in RFC 1055 in 1988, they made it perfectly clear that SLIP was "nonstandard" [1]. The protocol only provides Layer 2 framing when needed and does so in a very simple manner, so it was deemed that there was not enough going on to standardize it.
The way that SLIP frames data is that it simply appends a character to the end of each datagram to define its boundaries. It does not do much more than that, therefore error correction is not supported in SLIP [2]. Even before the IETF had issued RFC 1055, engineers were already working on a better protocol for directly connected computers and eventually came up with Point-to-Point Protocol (PPP), so SLIP is not used much anymore [1].
Point-to-Point Protocol provides services on both the Physical and Data Link Layer of the OSI model, which allows a modem to act as a network interface controller (NIC). Using several sub-protocols, PPP provides full Layer 2 connectivity through physically linked devices. These sub-protocols include, IP, IPX, and NetBEUI. Error checking and data compression are also supported making PPP faster and more reliable than SLIP [2]. The Point-to-Point protocol is pretty complex and I am not going to delve too deep into it for the sake of simplicity here, but if you are interested in learning more about it please check out the links. Suffice it to say that even though it is much more complex than SLIP, PPP has replaced SLIP for TCP/IP physical connections because of the much more robust service that it provides [2].
This concludes Part 8 of the the Data Transmission and Protocol series. In Part 9 I will clarify the difference between Hypertext Transfer Protocol (HTTP) and File Transfer Protocol (FTP). I know some of you are only a bit familiar with these two protocols. Anyone who has ever typed in a URL manually will at least have seen HTTP in the address. In Part 9 I will explain what it is and how it is used and give FTP the same considerations.
A serial connection exists on the Physical Layer of the OSI model. As such there is no way to arrange the data for transmission. So engineers created SLIP to help arrange the data for serial transmission. This was an informal protocol that for a while became the de facto standard for serial transmission, but it was never adopted as a true TCP/IP protocol. In fact, when the Internet Engineering Task Force (IETF) finally described it in RFC 1055 in 1988, they made it perfectly clear that SLIP was "nonstandard" [1]. The protocol only provides Layer 2 framing when needed and does so in a very simple manner, so it was deemed that there was not enough going on to standardize it.
The way that SLIP frames data is that it simply appends a character to the end of each datagram to define its boundaries. It does not do much more than that, therefore error correction is not supported in SLIP [2]. Even before the IETF had issued RFC 1055, engineers were already working on a better protocol for directly connected computers and eventually came up with Point-to-Point Protocol (PPP), so SLIP is not used much anymore [1].
Point-to-Point Protocol provides services on both the Physical and Data Link Layer of the OSI model, which allows a modem to act as a network interface controller (NIC). Using several sub-protocols, PPP provides full Layer 2 connectivity through physically linked devices. These sub-protocols include, IP, IPX, and NetBEUI. Error checking and data compression are also supported making PPP faster and more reliable than SLIP [2]. The Point-to-Point protocol is pretty complex and I am not going to delve too deep into it for the sake of simplicity here, but if you are interested in learning more about it please check out the links. Suffice it to say that even though it is much more complex than SLIP, PPP has replaced SLIP for TCP/IP physical connections because of the much more robust service that it provides [2].
This concludes Part 8 of the the Data Transmission and Protocol series. In Part 9 I will clarify the difference between Hypertext Transfer Protocol (HTTP) and File Transfer Protocol (FTP). I know some of you are only a bit familiar with these two protocols. Anyone who has ever typed in a URL manually will at least have seen HTTP in the address. In Part 9 I will explain what it is and how it is used and give FTP the same considerations.
[1] Kozierok, C. M. (2005). The TCP/IP Guide. Retrieved from http://bit.ly/qMaZ62
[2] What is SLIP/PPP?. (n.d.). Retrieved from http://sunsite.nus.edu.sg/pub/slip-ppp/whatis.html (no longer active)
No comments:
Post a Comment