QoS for Voice traffic

Unanswered Question
Sep 16th, 2008

I am trying to understand why a particular policy was put in place and what is it doing.

We have this at all of our remot ebranches which is using VoIP fo inter office calls:

policy-map PEFCU-QoS

class VOICE

priority 256

set dscp ef

class DATA-Priority

bandwidth 128

set dscp af31

class class-default

set dscp default



Each site has a full T1.

Am I to understand that anything mathing the access-list in class VOICE will get 256K of the pipe and will be prioritized over any other traffic?

And why the "priority" designation?

Does this give that traffic prioirty over any other class?

Also, the DATA gets 128K of the pipe and is prioritized only if there is not VOICE traffic?

And all othere traffic gets the rest of this pipe?

I have this problem too.
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Brandon Buffin Tue, 09/16/2008 - 09:41

The "priority" command speciifies both a minimum and maximum bandwidth guarantee and does give priority to this class which is necessary in the case of voice traffic. The "bandwidth" command will give this class a guaranteed mimimum amound of bandwidth. However, keep in mind that these commands only take effect when there is congestion on the link. At other times, the link bandwidth is available for any traffic. Take a look at the following link for further explanation.


Hope this helps. If so, please rate the post.


wilson_1234_2 Fri, 09/19/2008 - 08:38

We currently have this policy set up.

I am going to add some new routers to our network that will use a policy on the remote side.

Is there any way for me to verify that the new routers are getting their traffic prioritized per the policy if they need to have it prioritized?

Brandon Buffin Fri, 09/19/2008 - 09:52

You can use the "show policy-map interface" command to see the traffic that is being matched and prioritized such as:

show policy-map interface s0/0

Hope this helps.



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