Subject: [PCN] I-D ACTION:draft-ietf-pcn-sm-edge-behaviour-01.txt

From: [email-masked]
Date: Tue, 27 Oct 2009 09:45:01 -0700 (PDT)

A New Internet-Draft is available from the on-line Internet-Drafts 
directories.
This draft is a work item of the Congestion and Pre-Congestion Notification Working Group of the IETF.

	Title		: PCN Boundary Node Behaviour for the Single Marking (SM) Mode of Operation
	Author(s)	: A. Charny, G. Karagiannis, M. Menth, T. Taylor
	Filename	: draft-ietf-pcn-sm-edge-behaviour-01.txt
	Pages		: 12
	Date		: 2009-10-27
	
Precongestion notification (PCN) is a means for protecting quality of
   service for inelastic traffic admitted to a Diffserv domain.  The
   overall PCN architecture is described in RFC 5559.  This memo is one
   of a series describing possible boundary node behaviours for a PCN
   domain.  The behaviour described here is that for two-state
   measurement-based load control, known informally as Single Marking
   (SM).

A URL for this Internet-Draft is:
http://www.ietf.org/internet-drafts/draft-ietf-pcn-sm-edge-behaviour-01.txt

Internet-Drafts are also available by anonymous FTP at:
ftp://ftp.ietf.org/internet-drafts/

Below is the data which will enable a MIME compliant mail reader
implementation to automatically retrieve the ASCII version of the
Internet-Draft.

---

From: <[email-masked]>
Date: Wed, 28 Oct 2009 16:09:00 +0100

Hi Phil,

I'm not a staunch supporter of termination. I'm having a question related 
to termination of small aggregates.

Assume 10% excess marked traffic at a particular egress.

- 5 flows for IEA1
- 3 flows for IEA2

Each flow consumes the same bandwidth. 

I don't think that it matters whether decisions are taken at ingress or 
egress. The farther congestion is from an ingress or egress, the lower 
the number of IEAs. That means, that either the ingress or egress may 
control a number of small aggregate IEAs, depending on the location of 
the pre-congested interface.

As far as I understand, there's no way to signal which flows are the most 
burdensome for a pre-congested interface. Maybe the above 8 flows consume
10 times the average bandwidth of any other flow passing the pre-congested 
interface. The egress can't learn about that.

I'm not out for an endemic fairness discussion and I don't want to start 
a re-ECN discussion here. A pragmatic rule then would be "terminate 
one flow"? Or should the reaction be configurable?

I'm not looking for solutions which result in flow awareness at 
pre congested interfaces or centralised systems having an overview.

Regards,

Ruediger

Deutsche Telekom Netzproduktion GmbH 
Zentrum Technik Einführung 
Technik Internet Backbone, TE142-19
Rüdiger Geib
Heinrich Hertz Str. 3-7
64297 Darmstadt
Tel.: 06151/6282747
Fax: 0251/7985109

Deutsche Telekom Netzproduktion GmbH 
Aufsichtsrat: Dr. Steffen Roehn (Vorsitzender) 
Geschäftsführung: Dr. Bruno Jacobfeuerborn (Vorsitzender), Albert Matheis, Klaus Peren 
Handelsregister: Amtsgericht Bonn HRB 14190 
Sitz der Gesellschaft: Bonn 
USt-IdNr.: DE 814645262

---

From: Michael Menth <[email-masked]>
Date: Wed, 28 Oct 2009 17:08:08 +0100

Hi Rüdiger,

you are right that small overtermination can be problematic with small 
aggregates. This has been studied in Section 4.6 in
http://www3.informatik.uni-wuerzburg.de/~menth/Publications/papers/Menth08-Sub-9.pdf
and solutions that can be locally implemented have been proposed and 
demonstrated.

Regards,

    Michael

[email-masked] schrieb:
> _______________________________________________
> PCN mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/pcn
>   

-- 
Dr. Michael Menth, Assistant Professor
University of Wuerzburg, Institute of Computer Science
Am Hubland, D-97074 Wuerzburg, Germany, room B206
phone: (+49)-931/31-86644 (new), fax: (+49)-931/888-6632
mailto:[email-masked]
http://www3.informatik.uni-wuerzburg.de/research/ngn