RE: QoS in Shared Media

["Jay Wang" <jwang@opixnetworks.com>]

Pankaj,

-----Original Message-----
From: Pankaj K Jha [mailto:pkj@cypress.com]
Sent: Monday, May 07, 2001 4:46 PM
To: Jay Wang
Cc: Juha Heinanen; HANSEN CHAN; Fred Baker; Naidu, Venkata;
'mpls@uu.net'; te-wg@ops.ietf.org
Subject: Re: QoS in Shared Media

>DPT, on the other hand, will go ahead and divide available bandwidth
equally to
>all four nodes - ignoring whatever you may do with Diff-serv. DPT works
best
>when all nodes have equal bandwidth requirements, and it doesn't work when
you
>have dissimilar bandwidth needs. Dissimilar bandwidth needs are quite
common in
>metro networks where hub-and-spoke configurations are norm. If you have
>bandwidth paying customers such as financial institutions and corporate
clients
>on a metro ring along with average over-provisioned clients, DPT will not
do the
>job at all, in my view.


I believe DPT allows you to artificially specify a cap on the bandwidth, by
configuring the MAX_USAGE parameter, on a per-node basis. But even if all
the
nodes evenly divide the ring bandwidth, this does not mean that on each
node,
I can not provide differentiated treatment (in terms of forwarding and
bandwidth
allocation) among diffserv PHBs at the nodes.  Also if the nodes have very
different
BW needs, then they don't have to be placed on the same ring, a traffic
engineering
issue for the carrier.

- jay