RE: End System PMTUD behavior question

"Dunn, Jeffrey H." <jdunn@mitre.org> Wed, 21 January 2009 19:44 UTC

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From: "Dunn, Jeffrey H." <jdunn@mitre.org>
To: =?utf-8?B?UsOpbWkgRGVuaXMtQ291cm1vbnQ=?= <rdenis@simphalempin.com>, "ipv6@ietf.org" <ipv6@ietf.org>
Date: Wed, 21 Jan 2009 14:44:18 -0500
Subject: RE: End System PMTUD behavior question
Thread-Topic: End System PMTUD behavior question
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Cc: "Huang, Frank" <fhuang@mitre.org>, "Sherman, Kurt T." <ksherman@mitre.org>, "Liou, Chern" <csliou@mitre.org>, "steve_eiserman@uscourts.gov" <steve_eiserman@uscourts.gov>, "ipv6-bounces@ietf.org" <ipv6-bounces@ietf.org>, "v6ops@ops.ietf.org" <v6ops@ops.ietf.org>, "Grayeli, Parisa" <pgrayeli@mitre.org>
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ersus TCP; however, I am looking for some concrete documentation or experiences.

Best Regards, 
  
Jeffrey Dunn 
Info Systems Eng., Lead 
MITRE Corporation.
(301) 448-6965 (mobile)


-----Original Message-----
From: Rémi Denis-Courmont [mailto:rdenis@simphalempin.com] 
Sent: Wednesday, January 21, 2009 2:33 PM
To: ipv6@ietf.org
Cc: Dunn, Jeffrey H.; ipv6-bounces@ietf.org; v6ops@ops.ietf.org; Sherman, Kurt T.; Liou, Chern; steve_eiserman@uscourts.gov; Huang, Frank; Grayeli, Parisa
Subject: Re: End System PMTUD behavior question

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/
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