Effects of Qos on Cisco 7204, NPE-G1, 12.3(14)T7

Hi All,

Is there any information available about the effects of QoS on a Cisco 7204 NPE-G1 CPU?

Looking to implement QoS to DSL subscribers via Radius reply attribute on the Virtual-Access interfaces but not sure of the impact to the Cisco LNS terminating the PPP sessions

e.g.
A Policy-Map is configured to prioritise DSCP Marked VoIP traffic (Downstream) towards a users DSL Router, when the PPP session is authenticated, the Policy-Map is applied to the Virtual Interface and traffic is prioritised towards the end-user.

Question is, if I have this Policy applied to a large number of Virtual Access Interfaces on the LNS router, what effect will it have on CPU/Memory?

Is this just a matter of try and see or are there some references to effects of QoS on CPU etc.

Thanks in advance

Stephen
DScouserAsked:
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John MeggersNetwork ArchitectCommented:
No hard data I'm aware of.  I suspect somewhere deep inside the bowels of Cisco there are test results but those are generally not available to the public.  If you have a Cisco account team you work with, check with the SE, he should have access to BU contacts and may be able to find something.

What are you defining as a "large number of Virtual Access Interfaces"?  AFAIK, QoS doesn't generally add a great deal of processing power; the router still has to queue the packets, QoS just gives it guidance on what packets should be queued where.  Unless you're already running high CPU or memory, I wouldn't think it would make a huge difference, but it's been a long time since I've dealt with PPP so don't hold me to that.
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DScouserAuthor Commented:
Thanks for the reply,

I think you are right about this info not being available, been hard to find any kind of performance stats when applied to DSL subscriber sessions.  Each device terminates about 2,500 sessions but not all will have QOS applied so it may be OK.

Will just have to add it as a possible risk.

I'm meeting Cisco tomorrow so will see if they have any info and report back

Cheers
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DScouserAuthor Commented:
Spoke to a Cisco engineer this week about this, he says that a customer of his runs a 7200 NPE-G1 with approx 3,000 QoS sessions and CPU runs at nearly 80-85%

As I will not be activating QoS on every session I may be OK
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