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From: skip@ubvax.UB.Com (Stayton D Addison Jr)
Newsgroups: comp.protocols.tcp-ip,comp.dcom.lans
Subject: Re: A handful of 802.X questions
Message-ID: <3201@ubvax.UB.Com>
Date: Wed, 28-Oct-87 11:42:01 EST
Article-I.D.: ubvax.3201
Posted: Wed Oct 28 11:42:01 1987
Date-Received: Sat, 31-Oct-87 14:10:24 EST
References: <12030@labrea.STANFORD.EDU>
Reply-To: skip@ubvax.UUCP (Stayton D Addison Jr)
Organization: Ungermann-Bass, Inc.
Lines: 61
Keywords: IEEE 802, bridge, source routing
Xref: mnetor comp.protocols.tcp-ip:1554 comp.dcom.lans:892

In article <12030@labrea.STANFORD.EDU> morgan@jessica.stanford.edu (RL "Bob" Morgan) writes:
>In the wake of the IP-over-802 draft RFC, I'd like to ask a few
>questions:
>
>1.  Is any network anywhere using 802.2 over 802.3?  Does anyone
>running a large Inter-Ethernet have any plans to move to 802.2 over
>802.3?
>

UB's Token Ring - Ethernet Data Link Bridge puts the 802.5 packets on the
802.3 network, 802.2 LLC headers and all.

My incomplete understanding is that HP's TCP/IP implementation uses 802.3,
not Ethernet.  I don't know whether they use the 802.2 LLC headers.  

>2.  Is there any published justification for the use of source routing
>in IBM's bridging of token-rings, given its apparent violation of the
>network/logical-link/MAC layering principles?  Can anyone anywhere
>defend it?
>

Without endorsing the concept, I can repeat what I understand to be the
primary argument.  For security or other considerations (error rates, etc),
a node may want to direct the flow of its packets thru the internetwork to 
avoid certain routes/links.  In practice, I doubt many nodes have or will
ever do this.  

>3.  Is anyone anywhere doing MAC-level interconnection of token-ring
>and Ethernet/802.3 networks?
>

Yes.  Ungermann-Bass has announced an 802.3-802.5 Data Link Bridge.  
It doesn't do anything with Ethernet frames, however; just 802.3 (unless
the frames are from Ungermann-Bass equipment).  The problem is mainly the
ETYPE field which can not be derived from anything in the 802.5 header.

>4.  Has the 802.1 committee published anything about what it is up to?
>

I don't attend the meetings, but I understand that rev B of the 802.1
internetworking draft standard was published in March.  It was to be voted
on about now, I think.  

>5.  Is SNAP an official part of 802.2?  Is there anything written down
>about it anywhere?  It's not in my copy of 802.2.
>

Don't know.

>I've got lots more, but those will do for now.
>
>In wonderment,
>
>- RL "Bob" Morgan
>  Networking Systems
>  Stanford University
>  morgan@jessica.stanford.edu


-- Skip Addison
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