QOS on router with Avaya Phone System

[TRACY HARTMANN]

We need to add Qos to two routers that have a point to point T1s.  We are using a Avaya PBX and Avaya devices by default will tag all voice packets with

DiffServ Code Point DSCP- 46 (Expedited Forwarding),

and signaling with

DiffServ Code Point- DSCP 34

What is the best way to setup the QOS? 

[Terry Cheema]

Tracy,

You can use LLQ. LLQ consists of a priority queue for Voice traffic + CBWFQ for other classes. This model helps priortise Voice traffic and at the same time ensures other traffic is not starved.

Assuming you are using Cisco switches - Configure them to trust the markings at the source. The markings will be passed onto routers and at routers you can configure appropriate QoS mechanism.

At a very basic example:

R1(config)#class-map match-all VOIP-RTP
R1(config-cmap)#match dscp ef

R1(config)#class-map match-all VOIP-SIGNALING
R1(config-cmap)#match dscp afx      <<< chose acording to what your signaling is (34 - is af41 - normaly reserved for Video in Cisco)

R1(config)#policy-map VOIP
R1(config-pmap)#class-map VOIP-RTP
R1(config-pmap-c)#priority [kbps] or use priority %
R1(config-pmap)#class-map VOIP-SIGNALING
R1(config-pmap-c)#bandwidth [kbps ] or bandwidth percent

R1(config)#interface s0/0/0:0
R1(config-if)#service-policy out VOIP

You can setup more match criteria ACLs etc and add more classes. Its just a direction to start with.

Terry

[TRACY HARTMANN]

I think this will work for us, I am going to test it out next week.  Is there a way to monitor the usage from the router?

[Terry Cheema]

You can verify by running the command:

Sh policy-map interface

This will show you counters etc.

Let us know how did you go.

Terry

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