Path: utzoo!mnetor!uunet!husc6!cmcl2!rutgers!bellcore!faline!karn
From: karn@faline.bellcore.com (Phil R. Karn)
Newsgroups: comp.protocols.tcp-ip
Subject: Re: Response to Long Distance NFS Query
Message-ID: <1655@faline.bellcore.com>
Date: 22 Dec 87 20:39:32 GMT
References: <8712202159.AA13986@ucbvax.Berkeley.EDU> <1649@faline.bellcore.com> <1461@saturn.ucsc.edu>
Organization: Bell Communications Research, Inc
Lines: 15

> This [maintaining original Ethernet CRCs] is *NOT* a general
> characteristic of all bridges.

Don't I know it. Before the DEC Lanbridge came out, I built my own out
of PDP-11/73s and DEQNAs. Big mistake! The DEQNA has *major* problems
running in promiscuous mode. One common manifestation was undetected
packet corruption. Lots of funny entries showed up in our routing and
ruptime tables because UDP checksums were disabled on the Sun routers.

This experience made me a firm believer in end-to-end checksums for *all*
packets. The performance impact of UDP checksums in NFS is minimal, but
even if it weren't they would still be worth it.  Even ARP suffers from
the lack of an internal checksum.

Phil