QOS Help

[dontworx]

I am in need of some help. It is time for me to move from the relm of AutoQos to building my own policy-map's. I just got the 642-642 exam prep book, but the problem is that I need to do a project on Tuesday. The scenario I am looking for is I have two 1841 routers. The main site is a 10meg mpls pipe to fa0/0 and the remote site is a mpls t1 to s0/0. My phone system is tagging my voip for me using dscp. All I want to do is be able to implement QOS on the two routers for the voip traffice. I appreciate any help in advance. I am starting to get the Idea on how to do it, but I am still not totally sure. Thanks

 

[Nicegirl]

Hi dontworkx,

From your description I assume the setup is the following (both routers are configured as PE routers):
Phone <- Plain IP -> c1841 <--- MPLS Cloud ---> c1841 <- Plain IP -> Phone/Voice GW

The important think here is to keep in mind that for MPLS packets you cannot match on DSCP. So you will have to match on input (interface on the side of the phone) and use qos-group. An example of config would be the following (symmetric on both routers) :

On the input interface (on the side of the customer and phone) you should apply the following policy map to mark traffic (I assume voice traffic is marked with EF DSCP value):

Class Map match-all EF
Match dscp ef (46)

Policy Map MARKING
Class EF
set qos-group 46

On the output interface (on the side of the MPLS cloud) you should apply the following policy map to configure LLQ for voice traffic:

Class Map match-all VOICE
Match qos-group 46

Policy Map QUEUEING
Class VOICE
Strict Priority
Bandwidth 20 (%)
Class class-default
Flow based Fair Queueing
Bandwidth 0 (kbps) Max Threshold 64 (packets)


Please let me know if you need any precision.

Nicegirl

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