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--