Re: Adding headers and adding options to headers

[Philip Homburg <[e-mail]>]

>Again: I claim PMTUD is already broken and unfixable.
>(and should be replaced by PLMTUD, which should be turned on by default)
>
>What else does inserting headers break that isn't related to PMTU ICMPs?
>
>(I'm not in favour of inserting headers.  I am in favour of having rational
>and evidence based reasons in our specifications, or they will get ignored).

By and large PMTUD works. It doesn't always work, which is an issue. But
it largely works.

That said in my opinion all hosts MUST do some form of PMTU blackhole
detection. Unfortunately we can't write that down.

Also unfortunately, very few stacks seem to ship with PLMTUD enabled by
default. So any new feature in IPv6 that break PMTUD more is going to put
IPv6 at a significant disadvantage compared to IPv4.

I think we should focus on PMTUD with a fallback to PLMTUD. As far as I
know there are no major stack running with just PLMTUD and we have
no idea how it would work in practice.