Re: TOE brain dump

From: Lincoln Dale (ltd@cisco.com)
Date: Wed Aug 06 2003 - 03:20:06 EST


At 05:12 PM 6/08/2003, Andre Hedrick wrote:
>Do be sure to check that your data payload is correct.
>Everyone knows that a router/gateway/switch with a sticky bit in its
>memory will recompute the net crc16 checksum insure it pass the to the nic
>regardless. It is amazing how much data can be corrupted by a network
>environment via all the NFS/NBD/etc wantabie storage products out there.

Andre, you are wrong.

firstly, do you REALLY think that most router(s)/switch(es) out there
recompute IP checksums because they did a IP TTL decrement when routing an
IP packet or NAT IP addresses?

no, they don't. just like netfilter or router-on-linux is smart enough to
be able to re-code an IP checksum by unmasking and re-masking the old/new
values in a header, so does the most router vendor's code.

secondly, why would a router or switch even be touching the data at layer-4
(TCP), let alone recalculating a CRC?

i know you really like your "we do ERL 2 in iSCSI" pitch, but lets stick to
facts here eh?

cheers,

lincoln.

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