[tcpm] 793bis: variable MTU

Wesley Eddy <wes@mti-systems.com> Thu, 19 December 2019 16:53 UTC

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From: Wesley Eddy <wes@mti-systems.com>
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Date: Thu, 19 Dec 2019 11:53:38 -0500
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Subject: [tcpm] 793bis: variable MTU
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I'm not sure the comment & suggested NEW text below is quite correct.  I 
tracked the text in question down to being from RFC 6691 (and it first 
appeared in -03 of draft-ietf-tcpm-tcpmss-03, and it looks like it came 
about from a thread here: 
https://mailarchive.ietf.org/arch/msg/tcpm/LjfmysjQAKmTudpBgBa2Jp20O3M ).

On 8/28/2019 11:39 AM, Gorry Fairhurst wrote:
> OLD:
>    As a result, when the effective MTU of an interface varies, TCP
>    SHOULD use the smallest effective MTU of the interface to calculate
>    the value to advertise in the MSS option (SHLD-6).
> - what does "varies" mean here? The MSS is computed when the SYN is 
> exchanged
> is this actually just:
> NEW:
>    When multiple IP interfaces have different effective MTUs, TCP
>    SHOULD use the smallest effective MTU of the interface to calculate
>    the value to advertise in the MSS option (SHLD-6).