[150249] in North American Network Operators' Group
Re: Common operational misconceptions
daemon@ATHENA.MIT.EDU (Valdis.Kletnieks@vt.edu)
Mon Feb 20 09:43:54 2012
To: Masataka Ohta <mohta@necom830.hpcl.titech.ac.jp>
In-Reply-To: Your message of "Mon, 20 Feb 2012 15:42:56 +0900."
<4F41EB70.3080401@necom830.hpcl.titech.ac.jp>
From: Valdis.Kletnieks@vt.edu
Date: Mon, 20 Feb 2012 09:42:15 -0500
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
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On Mon, 20 Feb 2012 15:42:56 +0900, Masataka Ohta said:
> George Bonser wrote:
>
> >> It is seemingly working well means there is not much PMTU changes,
> >> which means we had better assumes some PMTU (1280B, for example) and
> >> use it without PMTUD.
>
> > It depends on the OS and the method being used. If you set the
> > option to "2" on Linux, it will do MTU probing constantly and
> > react to MTU changes.
>
> It actually does nothing.
Did you find this by just reading RFCs, or by actual code inspection?
> the hosts are keep assuming PMTU of 1400B and if local MTU
> is 1500B or less, no discovery is performed because "the
> probe size range is small enough".
And if the local MTU is 9000?
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