[asterisk-users] Cisco Router QOS and IAX2

[Dave Fullerton]

Bruce Reeves wrote:
> I'm needing some pointers from anyone who has been able to get Cisco 
> routers
> to recognize the iax protocol and perform QOS on it. Or if there is a 
> better
> way to get my iax traffic prioritized by the router.
> 

I just spent some time doing this myself. If your routers already can 
prioritize traffic based on the TOS bits in your IP traffic, setting the 
tos in iax.conf should be the first place to start. If your routers 
don't do that already you will need to mess with setting up 
queuing/policies on the routers. Here are some places to start:

Here are some awesome descriptions on how QoS works and what the 
different methods of implementing queuing and traffic shaping on Cisco 
hardware are. They may be a bit dated depending on what kind or routers 
you are using:
http://www.netcraftsmen.net/welcher/papers/qos1.html
http://www.netcraftsmen.net/welcher/papers/qos2.html
http://www.netcraftsmen.net/welcher/papers/qos3.html

Here are some pages from the wiki that talk about QoS on cisco hardware.

Not sure what "type" of queueing this uses, but it allocates a certain 
amount of available traffic to voice traffic. Any unused voice traffic 
will be shared by what's left:
http://www.voip-info.org/wiki/view/QoS+Cisco

This page seems to talk about CAR (Committed Access Rate):
http://www.voip-info.org/wiki/view/QoS+Cisco+IOS

I ended up using priority queuing on my routers, giving voice first 
priority and everything else lower priorities. Not the best solution but 
it was the easiest for me to implement with the versions of IOS I have. 
If you would like to see my configs, let me know.

-Dave Fullerton