Path: utzoo!attcan!uunet!cs.utexas.edu!tut.cis.ohio-state.edu!ucbvax!JERRY.INRIA.FR!huitema
From: huitema@JERRY.INRIA.FR (Christian Huitema)
Newsgroups: comp.protocols.iso
Subject: Re: CLNP over IP (was TCP/IP versus OSI)
Message-ID: <8905160745.AA13357@inria.inria.fr>
Date: 16 May 89 07:47:41 GMT
References: <8905160028.AA19926@mirsa.inria.fr>
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 43

Dave,

>You cite three situations.  The first has OSI, down to CLNP, running in
>an IP network.  You put in a TSB to allow CLNP to run over OSI Transport
>and then have it translated to run over TCP.  This sounds strange, to say
>the least.  Running CLNP encapsulated over IP, directly, where CLNP views
>IP as a link-level protocol, is far cleaner.

This is a very valid point. I am a bit surprised that nobody proposed a
``standard'' way to ferry CLNP segments as IP datagrams. I know that
there is a big strategic plan to make all the NSFNET a ``dual
protocol'' network; however, it may take some time to fulfill it...

Lets imagine a scenario of the form:

1- Local net runs OSI > TP4 > CLNP over LLC1 over (Ethernet, FDDi, what else..);
2- Local gateway encapsulate CLNP segments of adequate size > IP, sends
them to target gateway;
3- Remote gateway extract CLNP segments, sends them over LLC1 to target
machine, which processes CLNP, TP4, and OSI applications..

It is clean and transparent from an OSI point of view; several gateways
may be used in parallel to the same local net; routing is strictly
based on NSAP addresses, and not on some mysterious transport address
rewriting; flow control and retransmissions are performed end to end..
All these are straightforward advantages over the ``transport gateways''.

Then, why not? For it is even easier to set up a datagram router than a
transport gateway -- much less CPU is needed! Also, the spec is quite
easy to write -- would not need much more than a single page; we only
need to agree on:

1- The particular datagram protocol to be used, i.e. either IP or UDP;
2- If CLNP is run directly over IP, the ``protocol id'' for CLNP;
3- If CLNP is run over UDP, a ``standard port'' for CLNP;
4- Some miscellaneous details on how much to decrement the TTL, and the
maximum size of the CLNP segments;
5- If we want to move that to a grand scale, an ARP protocol for the
projection of NSAPs to IP subaddresses.

What do we wait to have all that written dow in some RFC?

Christian Huitema