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From: jmg@cernvax.UUCP (jmg)
Newsgroups: net.lan,net.dcom
Subject: Re: DECNET - IP/TCP
Message-ID: <285@cernvax.UUCP>
Date: Wed, 5-Mar-86 06:29:53 EST
Article-I.D.: cernvax.285
Posted: Wed Mar  5 06:29:53 1986
Date-Received: Fri, 7-Mar-86 08:26:29 EST
References: <1469@gitpyr.UUCP> <1474@brl-smoke.ARPA>
Reply-To: jmg@cernvax.UUCP (Mike Gerard, DD Division, CERN.)
Organization: CERN, Geneva/Switzerland
Lines: 17
Xref: watmath net.lan:1336 net.dcom:1722

In article <1474@brl-smoke.ARPA> ron@brl-smoke.UUCP writes:
>> Question:
>>    Can you have one set of systems running DECNET and another set
>>    running IP/TCP all on one DELNI without any special software/hardware ?
>> 
>Sure, as long as they don't want to talk to each other, you don't have
>to change anything.  There is a field called the PROTOCOL address that
>differentiates the different protcols in use.  The representative software
>modules for the various protocols will either not see or reject packets
>from the wrong protocol.  DECNET and IP use different numbers.
>
>-Ron
Don't forget that the ISO/IEEE version of Ethernet changes the protocol
ID field to be the LLC Data Unit count. DEC will be changing to this.
Any private use of the protocol ID field has to be agreed (with Xerox)
and has to be too large to be a possible LLCDU count. Software has to
be intelligent enough (!) to differentiate these cases.