15 nov. 2014 01:40, Ted Lemon <[email protected]> :

> On Nov 14, 2014, at 12:22 PM, Rémi Després <[email protected]> wrote:
>> If this is acceptable to whoever wants to deploy MAP-T, in due knowledge of 
>> its experimental status, it is not AFAIK acceptable in a standard. 
> 
> I do hear your point, Rémi.   

Understanding in what MAP-T is incompatible with IPv4 PMTU discovery is then 
progressing.
But, as shown below, your understanding of the point isn’t complete yet.
 
> However, the problem actually exists in RFC 6145, not in this document, and 
> RFC 6145 is a standards track document.  

Misunderstanding of yours: the problem does not exist in RFC6145:
- With the single translation of RFC6145, an IPv4 packet which is sent with 
DF=1 (as needed for PMTUD of RFC4821) will never be fragmented (neither before 
nor after translation).  This is simply because IPv6 routers never fragment 
packets. => RFC4821 isn’t broken by RFC6145
- That is double translation that brings the problem: an IPv4 packet sent with 
DF=1 (as needed for RFC4821)  can be fragmented after being translated back to 
IPv4. => RFC4821 is broken by MAP-T.

> Also, this is a topic that the working group discussed and considered 
> addressed long before the coin toss.

It is clear that real understanding of this point isn’t widely shared. (Even in 
your case, you needed to ask a number of clarifications).
That’s what makes this contribution worth doing: decisions have to be made with 
consciousness of significant facts.

>   So I think this counts as re-raising an issue that was previously 
> addressed, and not as an issue that would have any bearing on the current 
> discussion.

IMHO, a clear explanation of this contradiction between MAP-T and PMTU 
discovery of RFC4821 should be present in the draft itself. 
If I stopped spending energy to try and get it, it is because I felt a strong 
preference  of MAP-T authors for keeping it concealed, and I had to move to 
other activities.

Why then does the issue comes now? 
Because it is now that a proposal comes to promote MAP-T from experimental to 
standard.

I am sorry that this contribution goes against a smooth and easy acceptance of 
an IESG goof faith proposal, but significant facts need to be known.

Regards,
RD

PS: As this discussion continues, and as you didn’t answer my question about 
when the IESG should be informed, I hope you won’t find inappropriate my 
opening the channel now.

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