On 20/08/2014 13:55, Mark Andrews wrote: > 576 is the mimimum reassembly buffer size to be supported > by all IPv4 hosts. It is *not* the minimum path MTU size.
Indeed. In fact what I was trying to say, badly, is that the proposed change would de facto create a minimum path MTU of 1260 for IPv4, iff we want SIIT to work in the general case. Which is a choice we could make, but we'd need to be clear that we were making it. Brian > > The miminum link MTU is 68 bytes. RFC 791. > > Mark > > In message <[email protected]>, Brian E Carpenter writes: >> On 20/08/2014 11:24, Fernando Gont wrote: >>> Hi, Brian, >>> >>> On 08/19/2014 07:58 PM, Brian E Carpenter wrote: >>>>> It does seem kind of silly that we say "you must support MTU >= 1280 to r >> un >>>>> IPv6" and then allow PTB packets with an MTU < 1280. Any reason we can't >>>>> simply say that PTB packets < 1280 are invalid? >>>> Because of SIIT, that is equivalent to saying that the minimum IPv4 >>>> MTU is now 1260. That might be a discussion worth having, but 576 has >>>> been around for a long time. >>> Not sure what you meant about 576... that we can assume that to be a >>> minmum MTU, >> Yes, that hasn't changed since RFC 791 (although the way fragmentation >> is defined for IPv4 is rather different from IPv6, of course). >> >> Maybe we consider it acceptable that SIIT will break on paths that >> include a shorter-than-Ethernet link MTU. But we need to make that >> statement explicit. >> >> Brian >> >> or something else? >>> Thanks! >>> >>> Cheers, >> _______________________________________________ >> v6ops mailing list >> [email protected] >> https://www.ietf.org/mailman/listinfo/v6ops _______________________________________________ OPSEC mailing list [email protected] https://www.ietf.org/mailman/listinfo/opsec
