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From: jas@MONK.PROTEON.COM (John A. Shriver)
Newsgroups: comp.protocols.tcp-ip
Subject: Routers and Internet Protocol #77
Message-ID: <8707141453.AA15834@monk.proteon.com>
Date: Tue, 14-Jul-87 10:53:52 EDT
Article-I.D.: monk.8707141453.AA15834
Posted: Tue Jul 14 10:53:52 1987
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I've never seen any specification that requires IP routers to examine
the Protocol field in an IP datagram being forwarded.  I would argue
that it is improper for a IP router to do so.  This prevents
consenting users of the internet to use an experimental Protocol
across the Internet since some "router czar" has forbidden this
protocol.  My idea of IP, and IP routers, is that it should be
completely blind to what protocol is in use above it (with the
exception of ICMP).  This is the spirit of layering.

Another reason not to do this is that it's just *another* field to
have to check in the main forwarding loop of a router.  If everyone
solves all of the Internet's "control" problems in routers "with just
one little check" here or there, we'll never get the sort of
performance out of routers that the Internet community seems to want.
We have to keep forwarding packets as *simple* as possible, or we'll
have 68030 routers running at 50 (exaggeration) packets/second.

(Obviously, these are my opinions, not Proteon's...)