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Re: End System PMTUD behavior question
- To: ipv6@ietf.org
- Subject: Re: End System PMTUD behavior question
- From: Rémi Denis-Courmont <rdenis@simphalempin.com>
- Date: Wed, 21 Jan 2009 21:33:27 +0200
- Cc: "Dunn, Jeffrey H." <jdunn@mitre.org>, "ipv6-bounces@ietf.org" <ipv6-bounces@ietf.org>, "v6ops@ops.ietf.org" <v6ops@ops.ietf.org>, "Sherman, Kurt T." <ksherman@mitre.org>, "Liou, Chern" <csliou@mitre.org>, "steve_eiserman@uscourts.gov" <steve_eiserman@uscourts.gov>, "Huang, Frank" <fhuang@mitre.org>, "Grayeli, Parisa" <pgrayeli@mitre.org>
- In-reply-to: <3C6F21684E7C954193E6C7C4573B762701D3DD67DA@IMCMBX1.MITRE.ORG>
- Organization: Remlab.net
- References: <3C6F21684E7C954193E6C7C4573B762701D3DD67DA@IMCMBX1.MITRE.ORG>
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Le mercredi 21 janvier 2009 20:56:23 Dunn, Jeffrey H., vous avez écrit :
> Colleagues,
>
> We have been performing some PMTUD tests and have found that different
> operating systems handle PMTUD differently. Specifically, we found that the
> "ping" application behaves in the following way when the PMTU is set to
> 1280 and a 1500 octet ICMPv6 echo request is sent to that routed path. The
> hosts we tested:
I'm afraid ping applications are not representative of what the operating
system IP stacks do. Besides, there are no standards regarding the behavior
of "ping" in case of Path MTU problems; it's really up to the implementor of
each "ping" whether to report an error or to transparently fragment.
The behavior of real transport protocols, such as TCP, DCCP and SCTP is more
interesting when it comes to evaluating operating systems and their IP
stacks.
--
Rémi Denis-Courmont
http://www.remlab.net/