[c-nsp] QoS with Voice and Video

[Mike Louis]

I generally use CAC (call admission control on both my voice and video queues). I setup my voice on the priority queue with a priority bw reservation equal to my cac restrictions. I set the DSCP value to EF and match all of that to the service providers queue. Then i will setup the video with CAC value + 20% to allow for queueing of frames (per best practice from cisco) and mark that traffic DSCP 34 or AF41. I place this traffic in a bandwidth reserved queue only - non-priority, using the CAC Value + 20% as the bw statement.

I would also verify my topology from a hub and spoke standpoint and match CAC values there as well. All of this is important to maintaining proper quality. You can go farther with drop precedence within the queues themselves to protect certain classes within each queue from being dropped based on queue depth but i normally leave those values at the default unless i have multiple types of priority traffic in the same queue.

HTH

Mike

________________________________________
From: cisco-nsp-bounces at puck.nether.net [cisco-nsp-bounces at puck.nether.net] On Behalf Of Higham, Josh [jhigham at epri.com]
Sent: Tuesday, January 27, 2009 3:18 PM
To: Cisco Mailing list
Subject: [c-nsp] QoS with Voice and Video

This isn't specifically Cisco but hopefully is fairly on-topic.

What is the best practice (and real world) handling for voice and video
queues?

I am working on QoS implementation over our enterprise WAN (provider
supplied MPLS) and was told that it was ok to combine voice and video in
the priority queue, or even put video as priority and give voice a
dedicated, but not priority, class.

This is counter to everything that I knew/heard, which is that voice is
low bandwidth and not bursty, where video is high bandwidth and bursty,
so it could starve other queues.

My options are:

 * voice as priority, with video dedicated non-priority
 * voice and video combined as priority
 * video as priority, with voice dedicated non-priority

Does the queue starvation concern only matter if the priority queue is
using near 100% of the circuit?  I do have the ability to control the
bandwidth used at other points if that helps.  I want to avoid creating
jitter in either the voice or video classes.  Does anyone have any input
or references about what the best approach is?

Thanks,
Josh
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