Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!rutgers!ucla-cs!zen!ucbvax!YKTVMX.BITNET!ELINSKY From: ELINSKY@YKTVMX.BITNET (Jay Elinsky) Newsgroups: comp.protocols.tcp-ip Subject: Source routing Message-ID: <8707301712.AA18994@ucbvax.Berkeley.EDU> Date: Wed, 29-Jul-87 17:54:27 EDT Article-I.D.: ucbvax.8707301712.AA18994 Posted: Wed Jul 29 17:54:27 1987 Date-Received: Sat, 1-Aug-87 09:58:35 EDT Sender: daemon@ucbvax.BERKELEY.EDU Reply-To: IBM TCP/IP For VM List Distribution: world Organization: The ARPA Internet Lines: 33 This is from Jay Elinsky at IBM Yorktown, originally sent on the Bitnet- based IBM TCP/IP For VM Mailing list. He asked that it be forwarded to the TCP/IP mailing list. - Mark Bodenstein, Cornell University ----------------------------Original message---------------------------- I'm one of the developers of the VM code at Yorktown, and I want to clarify some possible misconceptions on this subject: 1) We use source routing only on Token Ring. Even on Token Ring, we can certainly also route through a router, if the destination host is on a different net or subnet. If the destination host is on a different ring with the same net or subnet number, we do indeed use source routing. I believe that this is consistent with the architecture of the Token Ring. Is it inconsistent with any existing implementation of TCP/IP over Token Ring? If so, I'd certainly like to know about it. 2) Re "No RIF field, no function": If a host is on the same ring, the ARP code will recognize it, and subsequent packets between the hosts have no routing field at all. 3) Our TCP/IP certainly is inter-operable with other TCP/IP implement- ations. That is our reason for supporting TCP/IP. To repeat what I said in (1), the source routing issue is only on Token Ring, and to the best of my knowledge our implementation is consistent with other TCP/IP Token Ring implementations, and with Token Ring architecture. 4) In the VM code, the Token Ring routing information is kept as part of the address translation cache. I think that's logical. Jay Elinsky IBM T.J. Watson Research Center Yorktown Heights, NY