srcampb@anagld.UUCP (Shawn R. Campbell) (08/02/89)
In looking over some ISO seminar documentation from 1987 I came up
with a couple of questions regarding the relationship between
CLNP and X.25. For 1980 X.25 (ISO 8878/A) there was a "glue"
(ISO 8473/DAD1) that was used to allow CLNP (ISO 8473) to be used
above the X.25. However, the "glue" is not used for 1984 X.25
(ISO 8208) instead CONS X.25 (ISO 8878) is used above the X.25.
The question is "Are there any instances of CLNP being used over
X.25 (1984/88) in any ISO architectures today?"
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Shawn Campbell | UUCP: {uunet,aplcen,netsys,sundc}!anagld!srcampb
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Shawn Campbell | UUCP: {uunet,aplcen,netsys,sundc}!anagld!srcampb
Analytics, Inc. | ARPA: SRCampbell@DOCKMASTER.ARPA or
Suite 200 | anagld!srcampb@uunet.uu.net
9891 Broken Land Parkway |
Columbia, MD 21046 | Voice: (301) 381-4300 Fax: (301) 381-5173
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=tozz@hpindda.HP.COM (Bob Tausworthe) (08/03/89)
The answer to the question is: yes. CLNP over X.25 is alive and well. The "glue" you refer is the SNDCF which maps the CLNP onto X.25 network service. CONS is very different from CLNP. CONS is a network service definition which maps X.25 onto CCITT's connectio oriented netywork service. CLNP/X.25 allows ISO's connectionless network service and protocol to use X.25 as a subnetwork. Several companies are either working on, or have such a service. GOSIP 1.0 allows for CLNP/X.25 Bob Tausworthe
forster@CISCO.COM (Jim Forster) (08/06/89)
Shawn, I'm by no means an expert on the specs, but I have read them, and I think I remember this: 8473/DAD1 was accepted and is an official part of 8473 (at least as official as appendices ever are), so it did not go away. I think your puzzlement is an effect of the great connection-oriented versus connection-less religious battles in the OSI process. These battles were resolved by the political process of declaring both methods as 'standards'. CLNP is the Connection-Less variety, CONS is the Connection-Oriented variety. GOSIP V.1 requires CLNP over both Ethernet & X.25. GOSIP V.2 added an CONS as an option. Generally it seems that in the US, CLNP is preferred over CONS. It's quite straightforward to make routers forward CLNP packets between X.25 and Ethernet, Token Ring, FDDI, T-1 rate serial lines or whatever. I guess if you're running CONS/X.25 you would turn around and run X.25 over Ethernet, which is advocated in the UK. I guess the extension of this is that you'd run X.25 over Token Ring and FDDI, but I've never heard that even muttered. Jim Forster cisco Systems