Subject: [Tsvwg] New I-D posted: draft-gunn-tsvwg-ef-admit-evaluation-00

From: Janet P Gunn <[email-masked]>
Date: Thu, 1 Mar 2007 17:46:32 -0500

Hi,

We have written a new I-D on Performance Evaluation of EF-ADMIT.

http://www.ietf.org/internet-drafts/draft-gunn-tsvwg-ef-admit-evaluation-00.txt

I'd be very interested in feedback, particularly in terms of how to refine 
the assumptions, to be more realistic, and in terms of suggestions for 
additional scenarios to model.

Thanks.

Janet

                  Performance Evaluation of EF-ADMIT
   A new Differentiated Services Code Point (DSCP), EF-ADMIT, has been 
   recommended for a class of real-time traffic conforming to the 
   Expedited Forwarding (EF) Per Hop Behavior (PHB) and admitted using a 
   strong Call Admission Control (CAC) procedure incorporating capacity 
   assurance, as compared to a class of real-time traffic conforming to 
   the EF PHB but not subject to strong CAC.  This document presents 
   modeling results demonstrating that EF-ADMIT traffic will experience
   low packet drop rates even when lack of strong CAC results in EF 
   traffic experiencing high packet drop rates.  The modeling shows the
   performance benefit is material at low to medium network access 
   speeds (e.g., 256 Kb/s to 1.5 Mb/s), but relatively inconsequential 
   at high access speeds (e.g., 45 Mb/s) and, by inference, backbone 
   speeds (100Mb/s and higher) where more bandwidth headroom is assumed. 
   Furthermore, mixing relatively long packets (e.g., 1500 byte video 
   packets) with relatively short packets (e.g., 200 byte voice packets) 
   in EF PHB causes significant degradation to short packet performance
   at low to medium access speeds.  Finally, the results show that 
   implementation can be effective utilizing either one queue with 
   combined EF and EF-ADMIT flows, or two queues with one forEF-ADMIT 
   flows and one for EF flows, with the choice of approach mostly a 
   matter of policy.

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