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From: MAP@LCS.MIT.EDU (Michael A. Patton)
Newsgroups: comp.protocols.tcp-ip
Subject: Router interoperability
Message-ID: <8910211840.AA00865@gaak.LCS.MIT.EDU>
Date: 21 Oct 89 18:40:58 GMT
References: <8910201828.AA04251@cincsac.arc.nasa.gov>
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   Date: Fri, 20 Oct 89 11:28:07 -0700
   From: "Milo S. Medin [NASA ARC NSI Project Office]" <medin@nsipo.nasa.gov>

   That's not exactly true.  I believe the routers will interoperate at
   least for IP if you use X.25 as your serial line protocol.  Both 
   Proteon and Cisco support X.25 framing now.  It's not a very nice
   solution, but it should work. 

That's not my understanding.  They both use X.25 framing to set off
the packets on the line, but they use different encapsulation to
provide header compression, protocol identification, etc.  This is
sort of analogous to ISO 802.3 vs Ethernet V2.  They are electrically
compatable and the low level framing is the same, but if one machine
speaks 802.3 and another speaks only Ethernet V2, they won't
communicate.  Packets sent by one are rejected as mal-formed by the
other.

   Both Proteon and Cisco have committed to implement PPP, and both
   companies had active participation in the working group. 

That's correct.  Basically the design of PPP is intended to give
enough flexibility to let them have any special handling they need and
a compatable framework to allow any two machines to work together with
whatever common features they implement.

	Mike Patton