* Albert E. Manfredi: > The minimum MTU for IPv4 is 68 bytes. Similarly, in IPv6, PMTU > *should* be allowed to be as small as 40 bytes + 8 bytes for the > fragmentation header + any more required by other options, as > determined by the source host.
RFC 791 does indeed say that, but some of us have been working on pushing the IPv4 MTU to some saner value, above 500-something bytes. Many implementations follow that now. > I know RFC 2460 doesn't read this way, but I believe this issue could > be resolved by going back to what RFC 791 really said. Supporting small fragments has high hidden costs. Some of them are addressed by the larger fragment ID in IPv6, but not all of them. There is still no way to authenticate an incoming ICMPv6 PTB message, so you have to be very conservative when processing them. Fragmenting down to 48 bytes is certainly not a good idea (and the current specs don't permit that, anyway). -- Florian Weimer <fwei...@bfk.de> BFK edv-consulting GmbH http://www.bfk.de/ Kriegsstraße 100 tel: +49-721-96201-1 D-76133 Karlsruhe fax: +49-721-96201-99 -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
