Re: Handling Packet Misordering?

Craig Partridge <craig@aland.bbn.com> Mon, 09 September 2002 20:31 UTC

Message-Id: <200209092031.g89KVTlF022419@aland.bbn.com>
To: Fred Baker <fred@cisco.com>
Cc: tcp-impl@grc.nasa.gov
Subject: Re: Handling Packet Misordering?
In-Reply-To: Your message of "Mon, 09 Sep 2002 12:18:41 PDT." <5.1.1.6.2.20020909120131.01dbfaf0@mira-sjcm-4.cisco.com>
Date: Mon, 09 Sep 2002 16:31:29 -0400
From: Craig Partridge <craig@aland.bbn.com>
Sender: owner-tcp-impl@grc.nasa.gov
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>My point is that the real alternative to accepting resolution of reordering 
>at the endpoints is doing something in the network while will guarantee 
>sequential packet ordering. That is something that could be pretty 
>interesting to design and implement in terms of complexity and brittleness 
>added to the network, and very possible has the same effects.

Just adding to Fred's comment.

There are a few known ways to use multiple paths for *one* hop and maintain
packet ordering.  Most are *not* work conserving so you lose some capacity
(i.e., capacity grows as .9 * n * <mumble> rather than n * <mumble>).

If you want to keep order when paths diverge for multiple hops, you've
got an exciting research project (esp. if you want to be close to work
conserving....)

Craig