On 03 Jan 2012, at 17:57 , Philip Homburg wrote: > - For IPv6, given that the host has to do the fragmentation, > a big minimum MTU is required. Otherwise, too much stuff > will end up being fragmented at 576.
There is no evidence for the claim above. When the minimum Link MTU for IPv6 *was* set to 576, that did not happen. Instead, most traffic was Ethernet MTU without fragmentation, and the next most common packet size was (Ethernet MTU - overhead for DSL encapsulation/tunnelling). Packets at 576 were seen -- but very very infrequently -- so they were NOT a particular burden on the end systems. > My guess is, that anybody who is running a links at less > than 1280 is just going to get a lot of trouble. That applies > both to the links you mentioned and any IPv6-to-IPv4 translators. Clearly it is more complex to run an IPv6 link below 1280 today than it was when IPv6 specifications supported a 576 byte MTU. Folks with such links tell me that it mostly works today. IPv6-IPv4 translators aren't going away. There are lots of other reasons they get deployed -- including transition and interoperability. > Most IPv4 links are bigger than 1280. So, those translators will seem to work > in most cases. IPv4 links smaller than 1280 will just see failures that > are quite hard to debug. Actually, IPv4 links with 576 byte MTUs aren't problematic. They have worked well for ~30 years now. RF links aren't going away, and they aren't all being replaced by IEEE 802.11 or IEEE 802.16 either. Cheers, Ran -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
