[e2e] Applications with UDP checksum disabled

Marcel Waldvogel marcel at news.m.wanda.ch
Mon Mar 11 13:29:56 PST 2002


Joerg Micheel wrote:

>Early versions of SunOS did that on NFS servers, to gain performance,
>until they discovered that this was a Bad Idea (tm) as you need some
>form of e-2-e integrity check. The particular problem discovered was
>that while you have FCS with Ethernet, some bus data transfers to or
>from the Ethernet card can be corrupted, which will screw up your
>data storage on the server.
>
The problem became really bad for people that were using NFS over 
checksum-turned-off UDP over could-not-do-checksums SLIP over dialup 
lines or direct serial links. Even with UDP checksums turned on, dialup 
lines still were a pain. (A quick Google search reveals that NFS over 
SLIP is still in use.)

-Marcel




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