Subject: [PCN] Comments on draft-charny-pcn-single-marking

From: Michael Menth <[email-masked]>
Date: Tue, 31 Oct 2006 09:05:50 +0100

Dear Anna,

I read your draft
http://standards.nortel.com/pcn/draft-charny-pcn-single-marking-00.txt

Here are my comments.

The draft heavily bases on the assumption that the preemption threshold 
is a fixed multiple of the admission threshold for all links in the 
network and Section 3.2.1 states that this restriction is not too severe.

I see this point a bit differently. Traffic engineering should try to 
avoid congestion in the failure-free case and if likely failures occur. 
Thus, links need some backup capacity. If the preemption threshold is a 
fixed multiple of the admission threshold, we get additional constraints 
for routing optimization because the backup capacity is exactly the same 
percentage on the links. This side condition makes routing optimization 
(or the layout of explicit primary and backup paths) more difficult and 
less efficient.

Despite my criticism I find the approach interesting since it saves a 
bit. However, I rather view it as a workaround for special networks 
where only one bit can be used for PCN marking. In the end, network 
efficiency is traded for a single bit.

Best wishes,

    Michael

-- 
Dr. Michael Menth, Assistant Professor
University of Wuerzburg, Institute of Computer Science
Am Hubland, D-97074 Wuerzburg, Germany, room B206
phone: (+49)-931/888-6644, fax: (+49)-931/888-6632
mailto:[email-masked]
http://www3.informatik.uni-wuerzburg.de/research/ngn

_______________________________________________
PCN mailing list
[email-masked]
https://www1.ietf.org/mailman/listinfo/pcn

---

From: "Anna Charny \(acharny\)" <[email-masked]>
Date: Tue, 31 Oct 2006 14:47:47 -0500

Hi Michael,

Indeed you are right that if routing optimisation is done, then having
an additional constraint on it is yet another tradeoff that needs to be
considered.  

Anna  

-----Original Message-----
From: Michael Menth [mailto:[email-masked]] 
Sent: Tuesday, October 31, 2006 3:06 AM
To: [email-masked]
Subject: [PCN] Comments on draft-charny-pcn-single-marking

Dear Anna,

I read your draft

Here are my comments.

The draft heavily bases on the assumption that the preemption threshold
is a fixed multiple of the admission threshold for all links in the
network and Section 3.2.1 states that this restriction is not too
severe.

Best wishes,

    Michael

--
Dr. Michael Menth, Assistant Professor
University of Wuerzburg, Institute of Computer Science Am Hubland,
D-97074 Wuerzburg, Germany, room B206
phone: (+49)-931/888-6644, fax: (+49)-931/888-6632
mailto:[email-masked]
http://www3.informatik.uni-wuerzburg.de/research/ngn