Re: End System PMTUD behavior question

Thomas Peterson <thomasp@iol.unh.edu> Thu, 22 January 2009 20:38 UTC

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From: Thomas Peterson <thomasp@iol.unh.edu>
To: "Dunn, Jeffrey H." <jdunn@mitre.org>
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Subject: Re: End System PMTUD behavior question
Date: Thu, 22 Jan 2009 15:38:03 -0500
References: <3C6F21684E7C954193E6C7C4573B762701D3DD67DA@IMCMBX1.MITRE.ORG> <200901212133.30109.rdenis@simphalempin.com> <3C6F21684E7C954193E6C7C4573B762701D3DD687B@IMCMBX1.MITRE.ORG> <42A4D5E1-C552-434C-90E3-DA3EF4A78688@iol.unh.edu> <3C6F21684E7C954193E6C7C4573B762701D3DD69D1@IMCMBX1.MITRE.ORG>
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On Jan 21, 2009, at 5:24 PM, Dunn, Jeffrey H. wrote:

> Thomas,
>
> We would be happy to see any results you may have concerning  
> application behavior during PMTUD.
>
> Best Regards,
>
> Jeffrey Dunn
> Info Systems Eng., Lead
> MITRE Corporation.
> (301) 448-6965 (mobile)
>
> -----Original Message-----
> From: Thomas Peterson [mailto:thomasp@iol.unh.edu]
> Sent: Wednesday, January 21, 2009 3:00 PM
> To: Dunn, Jeffrey H.
> Cc: Rémi Denis-Courmont; ipv6@ietf.org; Huang, Frank; Sherman, Kurt  
> T.; Liou, Chern; steve_eiserman@uscourts.gov; ipv6-bounces@ietf.org; v6ops@ops.ietf.org 
> ; Grayeli, Parisa
> Subject: Re: End System PMTUD behavior question
>
> Hi Jeffrey,
>
> This is Thomas Peterson from the InterOperability Laboratory at UNH.
>
> We have done extensive testing in this area and would be happy to work
> with you off line to examine this scenario.
>
> If you would like we can even set up your test topology in our lab.
>
> Thanks,
> Tom
>
> On Jan 21, 2009, at 2:44 PM, Dunn, Jeffrey H. wrote:
>
>> Rémi,
>>
>> I agree with you assertions concerning "ping" versus 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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>

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