Subject: Diffserv-Aware Traffic Engineering

From: "Sergio Beker" <[email-masked]>
Date: Mon, 22 Oct 2001 16:10:00 +0200

Hello,
In draft-ietf-tewg-diff-te-reqts-01, the Scenario 1 states:

For delay/jitter reasons it is undesirable to carry more than a
   certain percentage of EF traffic on any link. The rest of the
   available link bandwidth can be used to route other classes
   corresponding to delay/jitter insensitive traffic (e.g. Best Effort
   Internet traffic). The exact determination of this percentage is
   outside the scope of this requirements draft.

Could any one point me out to any paper dealing with the optimal proportion
of EF and AF/BE on any link, if it exists?

Also, If voice is being coded using variable bit rate coders, couldn't be
voice traffic be marked to use AF classes instead of EF class? In that case,
I think it would be more appropriate to describe the scenario as High
Proportion of Delay/Jitter Sensitive Traffic instead of voice traffic, to
avoid further discussions and to achieve generalisation.

Thanks in advance.

Sergio Beker

---

From: Lei Yao <[email-masked]>
Date: Mon, 22 Oct 2001 11:02:49 -0400

The optimal percentage of bandwidth allocated to the EF class depends on
your QoS objectives on delay, delay variation and loss rate as well as the
link rate. There is no theoretical model which can give you the answers.

AF is not suitable to transmit voice packets by definition. A significant
difference between EF and AF classes is that EF does not allow the drop of
en-queued packets while AF class allows so. Also AF class does not have
requirements on delay variation bound, which is essential for voice traffic.

-----Original Message-----
From: [email-masked] [mailto:[email-masked]]On Behalf Of Sergio Beker
Sent: Monday, October 22, 2001 10:10 AM
To: [email-masked]
Subject: Diffserv-Aware Traffic Engineering

Hello,

Thanks in advance.

Sergio Beker