Subject: [Diffserv] Application for the LBE, BH, NCT, LB whatever it's called...

From: "Yoram Bernet" <[email-masked]>
Date: Tue, 12 Dec 2000 10:49:00 -0800

After yesterday's WG meeting I offered to send some text describing an
application for the proposed pdb (currently called the BH pdb). BTW - I
think that this is a key enabling application for DiffServ. Here's the
text:

***************** start text ******************
Traditionally, QoS has been viewed as a set of tools that would
*prioritize* access to network resources for certain applications
(primarily multimedia applications). Over time, we have found that many
network managers want to use QoS to *protect* the network from certain
applications, in particular, from multimedia applications (that
typically use non-adaptive protocols - e.g. UDP). 

Conventional QoS mechanisms that focus on prirotization offer the
network manager the ability to control the amount of multimedia traffic
that is given prioritized resources. Excess is relegated to best-effort.
The problem is that this excess traffic can wreak havoc with network
resources even when it is relegated to best-effort service. Because this
traffic is non-adaptive and because it is significant in volume and
duration, it tends to sieze network resources, thereby compromising the
performance of other, more important applications that are also
relegated to best-effort service but that use adaptive protocols (TCP).
As a result, network managers often simply refuse to allow multimedia
applications to be deployed in resource constrained parts of the
network. 

The [foo] PDB enables the network manager to allow the deployment of
multimedia applications without losing control of network resources. A
limited amount of multimedia traffic may (or may not) be given
prioritized service using any of the prioritizing PDBs (e.g. VW, or
other AF based prioritizing services). Excess multimedia traffic can be
prevented from wreaking havoc with network resources by forcing it to
the [foo] PDB. 
***************** end text **********************  

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