Re: Manual PMTUD [was ...rfc2460bis-08]

A) The AD has made the call.  We should re-litigate on the ipv6 list a 
discussion and conclusion from the IETF list.

B) My argument was not about whether insertion was in and of itself 
disastrous (although I do personally think it is a very bad idea). 
Rather, my argument has been that the current text is unclear.  Some 
folks read it as permitting insertion.  Other folks read it as 
prohibiting insertion.  Unclear text, particularly for advancment to IS, 
is just not acceptable.

I only include B in this note because you chose to describe the 
arguments being made.

Yours,
Joel

On 3/19/17 11:34 AM, Michael Richardson wrote:
>
> Brian E Carpenter <brian.e.carpenter@gmail.com> wrote:
>     > It is really unthinkable to me to allow header insertion on the
>     > Internet until we have a working solution to PMTUD in all
>     > circumstances, which we don't, due to operators misconfiguring
>     > middleboxes to drop ICMPv6/PTB, and due to RFC4821 being a rarity.
>
> In this debate we have seen essentially four arguments:
>
> 1) insertion is bad because <appeal to authority>
> 2) insertion is bad because PMTUD
> 3) insertion is bad because IPsec AH
> 4) insertion is bad because other ICMP issue/hard-to-diagnose weirdness
>
> Perhaps we will agree that (1) is not an argument.
> My claim is that (3) is irrelevant, IPsec AH has sadly (very very sadly from
> my point of view) failed.
>
> The PMTUD argument would be persuasive for me if PMTUD via ICMP really
> worked. My experience is that there are just way many problems.  PLPMTUD
> has been the only way I've gotten IPv6 over IPsec tunnels (where there is an
> MTU constriction) to work consistently, and I had argued that 2460bis should
> standardize this rather than PMTUD.
>
> As for point (4), I think that we have a general problem here regardless of
> insertion.  It would be nice to come up with some solutions to the problems
> of insertion, noting that insertion is just something that shines light
> on a fundamental problem.
>
> --
> Michael Richardson <mcr+IETF@sandelman.ca>, Sandelman Software Works
>  -= IPv6 IoT consulting =-
>
>
>
>
>
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