[c-nsp] How to QoS Voice on a Cisco LNS (How to attach a service-policy to a Virtual-Interface?)

[Alexander Lucke]

Hi,

I have a problem with QoS and hope that someone else already solved such a problem and can help me here.

What I need to do is prioritizing Voice traffic on SDSL lines. 

For the upstream part, this is no problem as the CPE (a small cisco router) can do QoS on the ethernet interface. My problem is the downstream part. My LNS (Cisco 7206VXR/300) gets the PPPoE-DSL sessions via L2TP over a FastEthernet interface. I configured some vpdn-groups and some virtual-templates and everything works fine with normal data traffic. 

My problem is that - when reading some documentation (e.g. http://www.cisco.com/warp/public/105/pppoe_qos_dsl.html) - it seems impossible to do a "session based queueing/shaping/whatever". It seems only to support marking.

Did anybody solve this issue? How is it possible to let an LNS prioritize Voice traffic in the downstream direction?

And No, we do not have access to the DSLAMs or the DSL aggregation network but let's assume that we don't have congestion (no overbooking ;-) here.

Viele Grüße
Alexander Lucke
 
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alexander lucke · managing director
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