[comp.protocols.tcp-ip] PPP != SLIP; PPP != SLIP++

minich@d.cs.okstate.edu (Robert Minich) (01/13/91)

by fks@FTP.COM (Frances Selkirk):
|>  PPP is a newer protocol, designed to get around problems in SLIP.
| 	
| Specifically, PPP masks characters (in a given range) that a modem 
| might interpret as control characters and masks them. It transmits the
| masked character preceded by a character which signals to PPP that the 
| following character is masked. The receiving PPP implementation then 
| decodes the masked character. Because of this, PPP can actually be somewhat
| slower than SLIP, but it is more dependable. Assumably, that dependability
| should save you time in the long run.

Well, PPP does a bit more than that. :-) More specifically, it fills in
tons of deficiencies of SLIP. PPP handles issues such as passing multiple
protocols (eg, DECNET, AppleTalk, <fill in you vendor>, etc.),
tracking the quality of the PPP link, authentication, option
configuring, etc. One important example is having, say, a dialup machine
using PPP to obtain an IP address.
  As far as raw speed, PPP has the extra overhead of the PPP link layer
packet while SLIP is just raw IP with _NO_ link layer. If speed is a big
concern, then get a faster line to talk over. :-) Seriously, even with
some excellent compression techniques for TCP, response rate over slow
lines is going to be less than ideal. Hopefully, we'll all have access to
reasonable data lines by the year <????> and that issue will be moot. 
-- 
|_    /| | Robert Minich            |
|\'o.O'  | Oklahoma State University| "I'm not discouraging others from using
|=(___)= | minich@d.cs.okstate.edu  |  their power of the pen, but mine will
|   U    | - "Ackphtth"             |  continue to do the crossword."  M. Ho