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Re: Operational feedback on PMTUD

2017-03-19 22:23:22
Hi Ohta-san,
  Thanks for your comment.

On Mar 18, 2017, at 8:03 AM, Masataka Ohta 
<mohta(_at_)necom830(_dot_)hpcl(_dot_)titech(_dot_)ac(_dot_)jp> 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 
<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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