[alcatel-nsp] Question about Service QoS Policies on 7750SR

GARCIA DEL RIO Diego Diego.Garcia_Del_Rio at alcatel-lucent.be
Mon Feb 16 13:15:20 EST 2009

Hi Hsu,


            If your version of TiMOS allows it, you could run a
"port-parent" scheduler, which allows you to map the parent scheduler of
the queues in the SAPs to a port-level scheduler that will distribute
bandwidth between all it's children according to the configured


            If you don't have the port-schduler function (it appeared in
TiMOS 5.0r4 and onwards), sap-queues and schedulers behave "as expected"
when there is no congestion at the port level, that is, all egressing
traffic is less than the port's egress rate.


            If there is congestion though, and no port-scheduler is
configured, queues are indeed served in round-robin fashion with the
"expedited" queues (in in-profile state) being served exhaustively, then
"best-effort" (in-profile) and finally all out-of-profile queues.


            So.. in short, if using TiMOS 5.0 or newer, take a look at
port-level schedulers ;-)




Diego Garcia del Rio
New Product Introduction - Network Design Engineer 
IP Division
Alcatel-Lucent - Antwerpen
Mobile: +32 4734 30 245
OnNET 2 605 3871
Phone (+32) 3 2403871 
e-mail diego.garcia_del_rio at alcatel-lucent.com 

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From: alcatel-nsp-bounces at puck.nether.net
[mailto:alcatel-nsp-bounces at puck.nether.net] On Behalf Of Kila Hsu
Sent: 16 February 2009 16:46
To: alcatel-nsp at puck.nether.net
Subject: Re: [alcatel-nsp] Question about Service QoS Policies on 7750SR


Thanks a lot to Mark for the information about the ways to share a port
among SAPs.
However, my boss seems to like the idea that each SAP can have its own
queues and schedulers though..
So say if I still need to deploy QoS on a per-SAP base, anyone know how
the packets from different SAPs defined on a common port would be
scheduled, if each has its own queue/scheduler?
>From the config guide I do see the "expedite" setting have something to
do with "hardware scheduler", but it is not clear if the setting is used
in cases like this.
Any idea would be appreciated.

Kila Hsu


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