Subject: [Tsvwg] Updated Pre-Congestion Notification drafts

From: <[email-masked]>
Date: Thu, 16 Mar 2006 15:07:06 -0000

We have updated two drafts:

1./  Pre-Congestion Notification marking

http://www.ietf.org/internet-drafts/draft-briscoe-tsvwg-cl-phb-01.pdf 

2./  A Framework for Admission Control over DiffServ using
Pre-Congestion Notification  

http://www.ietf.org/internet-drafts/draft-briscoe-tsvwg-cl-architecture-
02.txt 

1./  Pre-Congestion Notification marking

http://www.ietf.org/internet-drafts/draft-briscoe-tsvwg-cl-phb-01.pdf
[pdf includes graphs of simulation results not in txt version]

Abstract:

Pre-Congestion Notification (PCN) builds on the concepts of RFC 3168,
"The addition of Explicit Congestion Notification to IP". However,
Pre-Congestion Notification aims at providing notification before any
congestion actually occurs. Pre-Congestion Notification is applied to
real-time flows (such as voice, video and multimedia streaming) in
DiffServ networks. As described in [CL-ARCH], it enables "pre"
congestion control through two procedures, flow admission control and
flow pre-emption. The draft proposes algorithms that determine when a
PCN-enabled router writes Admission Marking and Pre-emption Marking in a
packet header, depending on the traffic level. The draft also proposes
how to encode these markings. We present simulation results with PCN
working in an edge-to-edge scenario using the marking algorithms
described. Other marking algorithms will be investigated in the future.

Summary of main changes:

Done simulations, results are described in Appendix B and summarised in
Section 4.  

Various options for encoding the marking are described and discussed in
Appendix C.

Only one admission marking algorithm is now described. 

A pre-emption marking algorithm has been added

Re-organised material between the 2 drafts

More authors from more companies.

2./  A Framework for Admission Control over DiffServ using
Pre-Congestion Notification  

http://www.ietf.org/internet-drafts/draft-briscoe-tsvwg-cl-architecture-
02.txt 

Abstract:

This document describes a framework to achieve an end-to-end Controlled
Load (CL) service without the scalability problems of previous
approaches. Flow admission control and if necessary flow pre-emption
preserve the CL service to admitted flows. But interior routers within a
large DiffServ-based region of the Internet do not require flow state or
signalling. They only have to give early warning of their own congestion
by bulk packet marking using new pre- congestion notification marking.
Gateways around the edges of the region convert measurements of this
packet granularity marking into admission control and pre-emption
functions at flow granularity.

Summary of main changes:

New/revised material (in Sections 4 and 5) on Failures, Admission of
'emergency / higher precedence' session, Tunnelling and Mechanisms to
deal with 'Flash crowds' 

Re-organised material between the 2 drafts

We have a slot in Dallas tsvwg meeting to talk briefly about
progress/changes.

Any comments etc would be much appreciated. How to encode the admission
& pre-emption markings is something we'd particularly like comments &
discussion on (Appendix C of draft-briscoe-tsvwg-cl-phb-01).

Thanks,

Best wishes,

Joe Babiarz

Bob Briscoe

Kwok Ho Chan 

Anna Charny 

Stephen Dudley

Philip Eardley

Francois Le Faucheur

Vassilis Liatsos 

David Songhurst

Philip Eardley

Networks Researcher

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