The Free On-line Dictionary of Computing (30 December 2018):
Compressed SLIP CSLIP(CSLIP) VanJacobsen TCP header compression. A version of SLIP using compression. CSLIP has no effect on the data portion of the packet and has nothing to do with compression by modem. It does reduce the TCP header from 40 bytes to 7 bytes, a noticeable difference when doing telnet with lots of little packets. CSLIP has no effect on UDP, only TCP. (1995-05-28)