> Additionally: > >> On Aug 7, 2025, at 1:15 PM, Templin (US), Fred L >> <[email protected]> wrote: >> >> Many tunneling protocols live by “grace” and assume 1500 everywhere. But, >> robust >> tunneling protocols need to live by the “law”, and the law says 1280. > > And its subtle - for IPv4, they assume 1500 everywhere but it’s really 576 > after reassembly at the receiver. > > For IPv6, it’s 1280 over each hop BUT up to 1500 after reassembly at each > receiver. > > These and other aspects are why this isn’t just an op-ed.
I think the current text is fine from a historical perspective. For future recommendations I would prefer a recommendation that tunnels must support link-layer segmentation and reassembly. That could be UDP options FRAG or something else. Outer IP fragmentation is undesirable for multiple reasons. E.g. a tunnel tail-end has to reassemble _before_ it can check if the fragment chain belongs to a tunnel. Last I looked, a lot of IP fragments are part of attacks, and they are costly to process. Ole _______________________________________________ Int-area mailing list -- [email protected] To unsubscribe send an email to [email protected]
