Re: [Diffserv-interest] QoS in diffserv network

Zoltan.Balint@alcatel.be Mon, 10 November 2003 08:23 UTC

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Date: Mon, 10 Nov 2003 09:21:15 +0100
From: Zoltan.Balint@alcatel.be
Organization: Alcatel,
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To: Brian E Carpenter <brc@zurich.ibm.com>
Cc: Feng Y <feng6@uwindsor.ca>, diffserv-interest@ietf.org
Subject: Re: [Diffserv-interest] QoS in diffserv network
References: <web-29474620@uwindsor.ca> <3FAE86E8.3AE456E7@zurich.ibm.com>
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Brian, Feng,
mid3FAE86E8.3AE456E7@zurich.ibm.com">
Can we always assume that a higher service class provides
the same or a better service than any lower service class
in AF? 
    
No. There is no "higher" or "lower" built into AF. There
is simply the option of having one or more mutually
independent AF service classes, with an arbitrary number
of four service classes being named AF1, AF2, AF3, AF4
if you choose to use the recommended code points.

If you happen to give each of these classes equal weights
in a WFQ scheme they are all offering the same level of service.
That would be the case when the relative load in those classes was equal as well. But, since some
classes can be more loaded than others, the service seen in different classes does not
relate to the index of the AF class. Unless, of course, the scheduler was strict priority, which does
not conform to the requirements in RFC2597 (minimum bandwidth).


Regards,
Zoltan

<snip>