On serial lines, a ``de facto'' standard known as SLIP or
Serial Line IP is frequently used.
A modification of SLIP is known as CSLIP, or compressed SLIP,
and performs compression of IP headers to make better use of the
relatively low bandwidth provided by serial links. A different serial protocol is PPP, or Point-to-Point Protocol.
PPP has many more features than SLIP, including a link negotiation
phase. Its main advantage over SLIP is, however, that it isn't
limited to transporting IP datagrams, but that it was designed to
allow for any type of datagrams to be transmitted.