Serial Line Internet Protocol (SLIP)
The SLIP is a TCP/IP protocol used for communication between two machines that are previously configured for communication with each other. For example, your Internet service provider may provide you with a SLIP connection so that the provider’s server can respond to your requests, pass them onto the Internet, and forward your requested Internet responses back to you. The dial-up connection to the server is typically on a slower serial line which is rather than on the parallel or multiplex lines such as a line of the network you are hooking up to.
• This protocol was developed by Rick Adams in 1984.
• The initial purpose of this protocol was to connect Sun workstation to the Internet over a dial-up line using the modem.
• Using this protocol, workstations send raw IP packets over the line with a flag byte (OXCO) at the end for the framing purpose.
• If the flag byte occurs inside the IP packet, then character stuffing technique is used to solve this problem. For this, a two-byte sequence (OXDB, OXDC) is sent in its place.
• Although SLIP is the simple protocol, it has some major problems. They are:
- It does not perform any error detection and correction.
- SLIP supports only IP (Internet Protocol). So it cannot be used for other networks that do not make use of IP.
- It does not support the allocation of dynamic IP address as both the communication sites should be assigned to a specific IP address beforehand and both sites should know each other’s address.
- The SLIP does not provide any authentication. So both the communicating sites do not know with whom they are communicating.
- SLIP is not an approved Internet standard so that many different and incompatible versions can exist and makes networking difficult.
• A special END character (equivalent to decimal 192) marks the end of data.
• If an End character occurs naturally in data, SLIP includes a special ESC character before the END character. Due to this, the receiving computer does not prematurely stop receiving the packet.