Re: Operational feedback on PMTUD

Suresh Krishnan <suresh.krishnan@xxxxxxxxxxxx> · Mon, 20 Mar 2017 03:22:39 +0000

Hi Ohta-san,  Thanks for your comment.

On Mar 18, 2017, at 8:03 AM, Masataka Ohta <mohta@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

I wrote:

Just a procedural question.

Though rfc2026 says:

   A specification for which significant implementation and successful
   operational experience has been obtained may be elevated to the
   Internet Standard level.  An Internet Standard (which may simply be
   referred to as a Standard) is characterized by a high degree of
   technical maturity and by a generally held belief that the specified
   protocol or service provides significant benefit to the Internet
   community.

does rfc1981bis qualify?

But, no response yet.

In all fairness, your message was received two weeks after the end of a four week IETF last call (March 1). The editor and the shepherd are busy going through the responses received during the last call period trying to converge on text change proposals.

It seems to me that rfc1981 operationally failed

For example, see my presentation at APNIC32

	How Path MTU Discovery Doesn't work
	https://meetings.apnic.net/__data/assets/file/0018/38214/pathMTU.pdf

as a proof accepted by operational community that rfc1981 style
PMTUD has been, is and will continue to be failing.

I went through the presentation (very interesting) and it looks like you are talking about multicast PMTUD. Your point about ICMP filtering breaking PMTUD is valid has been raised many times during the last call. It has not really been *quantified* though (i.e. how much ICMPv6 filtering is there on the Internet). One piece of work (from 2012) that I am aware of

http://www.nlnetlabs.nl/downloads/publications/pmtu-black-holes-msc-thesis.pdf

did a fairly large scale study using RIPE Atlas probes (~1000 vantage points for IPv4 and ~400 vantage points for IPv6) that showed that ICMPv4 was filtered for between 4-6% of the paths while ICMPv6 was filtered for only 0.77-1.07% of the paths. I would like to know if there is any more recent measurement information that indicates ICMPv6 is not workable on the Internet. That would certainly help me judge whether 1981bis will qualify or not in the “successful operational experience”.

Thanks
Suresh

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