Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

Need simple QoS configuration

I need to configure QoS, and think what I am trying to do is very simple, but am starting to see cross-eyed when reading all of Cisco's documentation on ways to implement QoS. Could someone please point me in the right direction? Here is the story: We have 2 sites which are connected with a point-to-point T1. We have Cisco 2620 routers at each site. We have Catalyst 2950 switches at each site. We have phone switches at each site which are connected via IP. What I want to do is: I want to prioritize the switch ports that the phone switches connect to at each site, and I want the routers to recognize that marked traffic and give it priority. That's it. There must be a very simple way to do this. Help please! I am going to search thru other topics, too, to see if this has been posted before. Much appreciation for any help!!!



Re: Need simple QoS configuration

Hello Steve,

I too think QOS is a really hard job.

But, tell me are those cisco ip phones?

if so,

easy set up on the 2950 would be:

cdp enable

mls qos trust device cisco-phone

mls qos trust cos

and on the routers would be something like:

ip cef

class-map match-all voiceip

match ip precedence 5

policy-map policy1

class voiceip

priority #

interface fa0

service-policy output policy1

Hope this help a bit,



Re: Need simple QoS configuration

Dont forget to also mark your signalling traffic

class-map match-all sig

match ip precedence 3

New Member

Re: Need simple QoS configuration

Hi Vlad,

Actually, they are NEC phone switches. The phones themselves are regular digital units, it is the actual switches themselves which communicate via TCP/IP. That is what makes me think it shouldn't be all that hard. What I have tried is setting the cos to 5 on the ports the NEC switches connect to on our Catalyst 2950s. The router part is what confuses me, so the router config sample you said looks helpful. I will give it a try. Thank you for your response!


New Member

Re: Need simple QoS configuration

Hi Steve,

If you want to read about it, look up Low Latency Queuing, which Vlad gave you an example of above. For signalling traffic, you would use Class Based Weighted Fair Queuing, which is configured just like LLQ except it uses the bandwidth instead of the priority command. There used to be a limit of how much traffic could be assigned to the priority queue, 70 or 75% if I remember correctly.

Have fun,


CreatePlease login to create content