>> Whether that automatically solves the problem depends on whether >> PMTUD works, which is unpredictable. Therefore, if you want a protocol >> *design* that is universal, it can't depend on PMTUD. Disabling >> fragmentation on its own is not enough. (That isn't news.) >> >> The only universal solution therefore seems to be a fully specified >> PLPMTUD solution, either built into the protocol design, or available >> as a normative reference. I think that would be a better >> recommendation than simply saying "don't rely on fragmentation." > > Summary of my views: > > Networks MUST support PMTUD. > Networks MUST support IP level fragmented packets.
That is not realistic for the IPv4 Internet. IPv4 fragments do have a higher drop probability than other packets. Just from the fact that multiple end-users are sharing a 16 bit identifier space. > Protocols/applications SHOULD have PMTUD blackhole detection. > Protocols/applications SHOULD do PLPMTUD. > Protocols/applications SHOULD avoid IP level fragmentation. > >> IMHO RFC4821 isn't a sufficient normative reference for this. Possibly >> draft-ietf-tsvwg-datagram-plpmtud will do it for UDP-based protocols. But >> IMHO we need a solution for each transport protocol, with widely available >> libraries. > > Agreed. The libraries part is extremely important. Programmers implementing > applications should not have to worry about this, it should be taken care of > by the libraries they use. For them it should just work. Cheers, Ole _______________________________________________ Int-area mailing list Int-area@ietf.org https://www.ietf.org/mailman/listinfo/int-area
