Cisco Router 4321 QOS configuration questions

Hello EE,

I have a 4321 and prior to my starting I was told they had VOIP quality issues.  I've been looking through the routers to get my bearings and I see the following:
class-map match-any voice-control
 match dscp cs3
class-map match-any voice-bearer
 match dscp ef

policy-map wan
class voice-bearer
bandwidth percent 25
class voice-control
bandwidth percent 5

I am wondering if anyone can help me understand what this is really doing as I am looking to expand with making internet best effort, but I don't want to break anything that is there.  Though I am still trying to make sure I don't destroy anything
operationsITAsked:
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Ken BooneNetwork ConsultantCommented:
Ok so here goes:

class-map match-any voice-control
 match dscp cs3
class-map match-any voice-bearer
 match dscp ef


So the above says that anything with a dscp value of cs3 will fall into the class called voice-control and anything that has a dscp value of ef will fall into the class called voice-bearer.  So basically we just mapped certain types of traffic to classes so we can do something with them.

policy-map wan
class voice-bearer
bandwidth percent 25
class voice-control
bandwidth percent 5

Now this part creates a policy that says what to do with each class.  In this case  it says for anything that has been classified as voice-bearer gets 25% of the available bandwidth and any traffic classified as voice-control gets 5% of the available bandwidth.

One the policy has been applied on an interface it would go into effect.

Hope this helps.
operationsITAuthor Commented:
That is awesome thank you for the clarification!

Is there something for example if I want to add a smaller bandwidth or best effort to internet I could reference for these tags like ef and cs3?
operationsITAuthor Commented:
@Ken Boone CCIE #4649 one other question as you say to apply it to an interface.
I see our outside interface shows service-policy output wan
is this accurate given the policy is: policy-map wan
Ken BooneNetwork ConsultantCommented:
So to answer your first question - here is a link to document that describes a qos policy with multiple traffic classes.  There is a lot of options when it comes to this stuff.

http://networkengineering.stackexchange.com/questions/638/what-is-the-5-level-qos-model-through-config-example

For your second questions.  Yes, the statement on the outside interface that shows the service-policy output wan is applying the policy-map called wan to traffic going outbound from that interface.

Hope that helps.

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operationsITAuthor Commented:
Great information thanks
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