On Wed, 16 Jul 2003, Keith Moore wrote:
so it seems like what we need is a bit in the IP header to indicate that
L2 integrity checks are optional
A lot of folks seem to forget that from the point of view of IP L2
includes the busses between memory and the L2 network interface. There
have been more than a few recorded cases where packet errors were
introduced as the packet flowed in or out of memory, unprotected by link
CRCs.
To my way of thinking we don't need a bit in the IP header, we need a bit
in the heads of implementors to remind them that relying on link-by-link
protection can be dangerous even if the links have strong CRCs.
... IP option to provide a stronger checksum than normally exists
The last time I saw a comparision of checksum algorithm strengths was back
in the OSI days when the IP checksum was compared to the OSI Fletcher
checksum (my memory is that the IP checksum came in second.)
--karl--