Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!van-bc!skl From: skl@van-bc.UUCP (Samuel Lam) Newsgroups: comp.unix.aix Subject: Re: NFS over serial link Summary: NFS normally doesn't use the UDP checksum! Keywords: NFS, SLIP, UDP, Checksum Message-ID: <3@van-bc.UUCP> Date: 28 Sep 89 10:45:30 GMT References: <1139@msa3b.UUCP> Reply-To: skl@wimsey.bc.ca (Samuel Lam) Organization: Balliffe International, Vancouver, B.C., Canada Lines: 21 In article <1139@msa3b.UUCP>, kevin@msa3b.UUCP (Kevin P. Kleinfelter) wrote: >The instructor says he knows of no reason why it should not work with >a serial link. ... If it won't work, why not? Most (all?) implementations of NFS doesn't use the UDP checksum for error detection, and thus rely on whatever's below IP to be error-free. In the Ethernet and Token Ring environment this works okay because of the relative reliability of the hardware, but on a SLIP line the chance of a datagram getting corrupted in the middle but still arrive at the other end is usually much higher, especially if you are using low-speed modems without automatic error correction for the link. So, I guess the answer is it will work most of the times, but for the times that it doesn't work, you might not know until too late. [ If AIX's NFS implementation actually uses the UCP checksum, then you can just ignore what I said above. ] ...Sam -- Samuel Lamor {uunet,ubc-cs}!wimsey.bc.ca!skl