> This conversation is missing some fundamental points – really the most > important > points – which are the minimum sizes guaranteed to work everywhere. For IPv6, > the minimum MTU/MRU are 1280/1500. For IPv4, they are only 68/576 but since > the IPv4 network supports fragmentation we can nominally designate the IPv4 > minimum MTU as 576 also if we clear the DF bit. It means that, without probing > or having some divine knowledge of paths that have not been previously > visited, > the ONLY sizes guaranteed to work are 1280 for IPv6 and 576 for IPv4.
Well "ifconfig eth0 mtu 1400" makes all this work. > Now take the case of Multinet where a path may traverse multiple concatenated > IP networks of arbitrary IP protocol versions - remember “Catenet”? Since > there > may be no advanced knowledge of network IP protocol versions, the most we can > absolutely and for sure count on across the entire path is 576. Are you talking about 4to6 and 6to4 translation? Then just "ifconfig eth0 mtu 1260". > What this gives us is not the *maximum packet size*; instead, it determines > the > *minimum cell size*. We know that a 576 cell will traverse all paths, so we > never > send a non-final cell smaller than this (which might trigger a tiny fragment > alarm). > But, we can certainly send packets larger than the path MTU - *much* larger in > many cases. And for paths that support them, we can also send Brian’s > jumbograms. I believe you are over thinking this. Just my opinion, no offense intended. Dino _______________________________________________ Int-area mailing list Int-area@ietf.org https://www.ietf.org/mailman/listinfo/int-area
