Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!MATHOM.CISCO.COM!BILLW
From: BILLW@MATHOM.CISCO.COM (William "Chops" Westfield)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: PPP on STREAMS
Message-ID: <12653501630.15.BILLW@mathom.cisco.com>
Date: 13 Jan 91 06:40:25 GMT
References: <9101112042.AA06101@ftp.com>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
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    >  PPP is a newer protocol, designed to get around problems in SLIP.

    [Stuff about masking dangerous characters]

This is only one of the problems PPP was designed to solve.  Off the
top of my head, here are some others:

  PPP has a CRC covering the whole packet, SLIP uses the IP/TCP/UDP
  checksum, which was (a) never intended to detect the types of errors
  likely to occur in async transmission, and (b) not always present
  (NFS comes to mind).

  PPP is designed to support protocols other than IP.

  PPP includes a negotiation protocol to negotiate "stuff", like the
  address of each end, compression, encryption, authentication, protocols,
  and so on.  Many people seem to think that PPP implies support of TCP
  header compression, but this is just an option that can be negotiated.

  PPP is defined for both Sync and Async communications.  Things like
  async PPP to sync PPP translation are theoretically possible.

On the dim side, PPP is very new, so not all of its advantages are
exploited by the implementations currently available.  Currently,
IP is the only protocol widely supported (and the only one that has
made it to RFC status, I think.) Hopefully, time will change this.

Bill Westfield
cisco Systems.
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