3376c58

5.8 Serial Line IP (SLIP)

The TCP/IP protocol family runs over a variety of
network media: IEEE 802.3 and 802.5 LANs, X.25 lines, satellite links, and
serial lines. Standards for the encapsulation of IP packets have been defined
for many of these networks, but there is no standard for serial lines. SLIP is
currently a de facto standard, commonly used for point-to-point serial
connections running TCP/IP. It is not an Internet standard.

SLIP is just a very simple protocol designed quite a long time ago and is
merely a packet framing protocol. It defines a sequence of characters that
frame IP packets on a serial line, and nothing more. It does not provide any:

lAddressing: both computers on a SLIP link need to know each other's IP
address for routing purposes.
lPacket type identification: thus, only one protocol can be run over a SLIP
connection.
lError detection/correction: error detection is not absolutely necessary at
the SLIP level because any IP application should detect corrupted packets (IP
header and UDP/TCP checksums should be sufficient). Because it takes so long to
retransmit a packet that was altered, it would be efficient if SLIP could
provide some sort of simple error correction mechanism of its own.
lCompression.