Re: Comments on WIMP and MTU Handling

["Spencer Dawkins" <spencer@mcsr-labs.org>]

Exactly - as if we needed application interaction for multi6, like you
had for ipv6 itself...

Spencer

----- Original Message ----- 
From: "Margaret Wasserman" <margaret@thingmagic.com>
To: <multi6@ops.ietf.org>
Sent: Wednesday, March 03, 2004 9:58 AM
Subject: Comments on WIMP and MTU Handling


>
> As I just discussed at the meeting mic, some of the multi6 proposals
> that involve a mid-Internet layer wedge (including WIMP and NOID)
> have an issue with IP fragmentation and reassembly.  If an ID/Loc
> layer will exist conceptually below the fragmentation/reassembly
> function, it is problematic for it to add optional bytes to the
> packet (such as a header or IP option that may or may not be
> included).  There are some possibilities for dealing with this:
>
>      - Run the ID/Loc separation between the Network and Transport
> layers instead.
>      - Reduce the MTU presented to upper layers, so that there is
> always room for the optional header.
>
> If you choose the second option, though, there is no advantage to
> mechanisms that try to avoid the need to add a header (such as the
> special next header values used in NOID).
>
> WIMP also adds another twist on this problem by forbidding
> fragmentation of packets that contain WIMP headers.  There is no
> indication of how/if the upper layers will cooperate to make this
> possible, or what impacts this requirement might have on Path MTU
> discovery.
>
> Margaret
>
>
>