Re: [TERNLI] Notes from tonight's ad hoc

Wesley Eddy <weddy@grc.nasa.gov> Fri, 28 July 2006 18:48 UTC

Received: from [127.0.0.1] (helo=stiedprmman1.va.neustar.com) by megatron.ietf.org with esmtp (Exim 4.43) id 1G6XOF-0003lH-Un; Fri, 28 Jul 2006 14:48:51 -0400
Received: from [10.91.34.44] (helo=ietf-mx.ietf.org) by megatron.ietf.org with esmtp (Exim 4.43) id 1G6XOE-0003lC-0f for ternli@ietf.org; Fri, 28 Jul 2006 14:48:50 -0400
Received: from mx2.grc.nasa.gov ([128.156.11.69]) by ietf-mx.ietf.org with esmtp (Exim 4.43) id 1G6XOC-00083b-Kb for ternli@ietf.org; Fri, 28 Jul 2006 14:48:49 -0400
Received: from lombok-fi.grc.nasa.gov (seraph4.grc.nasa.gov [128.156.10.13]) by mx2.grc.nasa.gov (Postfix) with ESMTP id 84E7BCC32 for <ternli@ietf.org>; Fri, 28 Jul 2006 14:48:47 -0400 (EDT)
Received: from apataki.grc.nasa.gov (apataki.grc.nasa.gov [139.88.112.35]) by lombok-fi.grc.nasa.gov (NASA GRC TCPD 8.13.7/8.13.7) with ESMTP id k6SImkUt017545; Fri, 28 Jul 2006 14:48:46 -0400 (EDT)
Received: from localhost (localhost [127.0.0.1]) by apataki.grc.nasa.gov (NASA GRC TCPD 8.13.7/8.13.7) with ESMTP id k6SImkcb010619; Fri, 28 Jul 2006 14:48:46 -0400 (EDT)
Received: from apataki.grc.nasa.gov ([127.0.0.1]) by localhost (apataki.grc.nasa.gov [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 08377-13; Fri, 28 Jul 2006 14:48:45 -0400 (EDT)
Received: from drpepper.grc.nasa.gov (gr2134391.grc.nasa.gov [139.88.44.123]) by apataki.grc.nasa.gov (NASA GRC TCPD 8.13.7/8.13.7) with ESMTP id k6SImfFg010569; Fri, 28 Jul 2006 14:48:41 -0400 (EDT)
Received: by drpepper.grc.nasa.gov (Postfix, from userid 501) id E794A4FCE5; Fri, 28 Jul 2006 14:50:07 -0400 (EDT)
Date: Fri, 28 Jul 2006 14:50:07 -0400
From: Wesley Eddy <weddy@grc.nasa.gov>
To: Mark Allman <mallman@icir.org>
Subject: Re: [TERNLI] Notes from tonight's ad hoc
Message-ID: <20060728185007.GG7604@grc.nasa.gov>
References: <002301c6b23f$a3ef4a90$0300a8c0@kfallmobl> <20060728125608.670AF444391@lawyers.icir.org>
Mime-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="PuGuTyElPB9bOcsM"
Content-Disposition: inline
In-Reply-To: <20060728125608.670AF444391@lawyers.icir.org>
User-Agent: Mutt/1.5.5.1i
X-Spam-Score: 0.0 (/)
X-Scan-Signature: 52f7a77164458f8c7b36b66787c853da
Cc: ternli@ietf.org
X-BeenThere: ternli@ietf.org
X-Mailman-Version: 2.1.5
Precedence: list
Reply-To: weddy@grc.nasa.gov
List-Id: Transport-Enhancing Refinements to the Network Layer Interface <ternli.ietf.org>
List-Unsubscribe: <https://www1.ietf.org/mailman/listinfo/ternli>, <mailto:ternli-request@ietf.org?subject=unsubscribe>
List-Archive: <http://www1.ietf.org/pipermail/ternli>
List-Post: <mailto:ternli@ietf.org>
List-Help: <mailto:ternli-request@ietf.org?subject=help>
List-Subscribe: <https://www1.ietf.org/mailman/listinfo/ternli>, <mailto:ternli-request@ietf.org?subject=subscribe>
Errors-To: ternli-bounces@ietf.org

On Fri, Jul 28, 2006 at 08:56:08AM -0400, Mark Allman wrote:
> 
> I guess I see the signals as either ...
> 
>   + Giving the transport something it can directly use.  E.g., the
>     available bandwidth just increased from 2Mbps to 11Mbps.  E.g.,
>     the flow experienced congestion.  E.g., some probability of the
>     fraction of losses due to corruption.
> 
>     These are different from less-directly-useful information like
>     "switched to a new AP" or "am now using a different coding /
>     modulation scheme" which are much less directly applicable. 
> 
>   + Giving a generic signal that *something* has changed and it likely
>     matters and so the transport should re-init itself (e.g., forget the
>     SRTT, RTTVAR, cwnd, ssthresh, MTU value, etc.).

Is it possible to generalize this to say that signals should either
carry specific actionable information or request specific types of
actions?

This means:
"Modulation changed" is a bad signal to implement.

"Available capacity changed from X to Y, please probe" is a good signal
to implement, and could be generated in response to a change in
modulation or any number of other things.

"Registering a new Mobile IP CoA" is a bad signal to implement.

"Please reprobe path state" is a good signal to implement, and could be
generated in response to a MIP CoA update or several other events from
mobility or multihoming mechanisms.


I guess this might simplify our task into categorizing the actions that
each layer might implement, and defining a signal for each class of
actions (with optional additional data to accompany the signal such as X
and Y in a capacity change signal -- you could define specific
combinations of X and Y to mean "up", "down", and "I don't know", when
specific values aren't available).

-- 
Wesley M. Eddy
Verizon Federal Network Systems