Setting up QOS for Voice on 8Mbps Leased on Circuit

Unanswered Question
Nov 12th, 2008


I have 4 nos 2Mbps aggreagated link on two 2811 router.I have configured a multilink ppp for aggregation.How can i setup QOS for voice calls on the link.

The protocol used is H.323 .How to identify the voice traffic on router.Can NBAR be used to identify the traffic ?

I have this problem too.
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saimbt Thu, 11/13/2008 - 00:12

You can either do this on the basis of network and ports and assign the voice traffic to a srtict priority queue. OR

If the device is capable of marking DSCP, you can trust DSCP on the access switches and assign bandidth to EF


Joseph W. Doherty Thu, 11/13/2008 - 05:39

One way to prioritize voice would be usage of a CBWFQ service policy, outbound, on your multilink interface. Place the voice into a LLQ class.

For identification, as Sai notes, the voice might (or can) tag their packets and you could match against their ToS. And/or identification via an ACL and/or NBAR. (The later NBARs do support matching against many kinds of voice traffic.)


Don't neglect special treatment of voice signally traffic.

Mohamed Sobair Thu, 11/13/2008 - 05:53


NBAR is used for traffic classification, you can use NBAR to classify voice traffic or an access-list , bellow an example for both:

class-map match-any (name)

match protocol rtp audio


class-map match-any (name)

match access-group 100

access-list 100 permit udp range 16348 32767

you then add the Class to a defined policy and apply it to the interface.




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