[c-nsp] QoS concerns

[Arie Vayner (avayner)]

Mihai,

Please see inline.

Arie

-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Mihai Todor
Sent: Thursday, June 10, 2010 13:12
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] QoS concerns

Hello,

I have some issues related to QoS I hope you might help to shed some
light
upon:

1. Is there any maximum bandwidth allocation percentage for the LLQ
deployed
in conjuction with CBWFQ/MDRR so as to enssure that other non-priority
traffic classes are not starved when PQ utilizes the maximum bandwith.
The
plaforms details are:
- XR 12406, SIP 601, SPA-10X1GE-V2 running IOS XR 3.8.0
- 7609-S, SIP 600, SPA-5X1GE-V2 running IOS 122-33.SRB5 Advanced IP
Services
[Arie Vayner] Yes. Every time you configure a priority class you have to
specific a policer value (will be active only when there is congestion).
This can be done either after the priority keyword or as an explicit
police command in the class (will be active at all times).

2. Is there any possibility that a 7206VXR performace is impacted by
deploying traffic marking policies based on input interface? The plaform
configuration is:
- 7206VXR, NPE-G1, PA-2FE-TX running IOS 124-15.T9 Advanced IP Services
[Arie Vayner] Yes, but for just marking the impact should be quite low.
On platforms like 7200 (software bases) any feature has some impact on
CPU.

3. Has anyone deployed with satisfying results the classification of
voice
traffic within a normal class (not priority)? The benefit would be the
possibility of borrowing bandwith from the other classes when available.
[Arie Vayner] For VOIP you need to maintain low jitter, which is what
the priority queue does. Using a non-priority class for VOIP would
potentially create a high jitter stream, which would reduce the voice
quality.

Many thanks for any of your comments!

Mihai


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