At 10:18 23/08/01, John Kristoff wrote:
Certainly. In a nutshell, it might be best to take steps to avoid fragmentation elsewhere in the network. Perhaps a rule of thumb that should be stressed is to use jumbo frames if you know for sure the other end system(s) support it, otherwise default to 1500.
Or just use Path MTU Discovery. For IP traffic that is traversing more than one layer-2 network, the variety in network technologies (e.g. ATM, SMDS, POS, Radio, Satellite, other) means that even ~1500 byte IP frames might not always work end-to-end. For example, I know of several commercial IP/SATCOM systems that have an MTU of 576 bytes. Many ISPs, not all, seem to try to engineer an end-to-end MTU of 4470 (that number chosen for historical reasons relating to FDDI). Some ISPs use a smaller MTU number and some use a higher MTU number. Ran rja@inet.org