I had a similar problem: I need to throttle and shape the outbound/egress traffic BEFORE it hits a branch office T1 router. Our ISP provides the T1 with MPLS for our WAN and they want to charge us $$$/month for deploying QoS. Basically I need to give my remote office higher priority for VoIP traffic over all other traffic. After playing with different configs, I finally have a good working setup. Hope this will help others.
The problem is the SRR bandwidth command has a range of 10% to 90% and our ISP router connects at 100Mbps. So the lowest I can limit is 10Mbps (10%). But I need to get much lower... like 1.5Mbps. After reading several postings for ideas, I forced the port speed to 10/Full and then use the SRR commands rate limit my egress port speed and give priority to my voice traffic.
First you must make sure to map your DSCP to one of the four egress queue like so: (auto qos will automatically generate this for you)
mls qos srr-queue output dscp-map queue 1 threshold 3 40 41 42 43 44 45 46 47
Then setup you router port like so:
interface FastEthernet0/23
switchport access vlan 10
speed 10
duplex full
srr-queue bandwidth share 50 10 10 30
srr-queue bandwidth shape 0 0 0 0
srr-queue bandwidth limit 20
queue-set 2
priority-queue out
mls qos trust dscp
spanning-tree portfast
You'll have to play with the "srr-queue bandwidth limit 20" command as it doesn't match exactly. This gives me about 1.5Mbps total traffic limit. More logically, a value of 15% on a 10Mbps link translates to 1.5Mbps, but it actually limits me to about 1.02Mbps. So play with it.
As you can see, I give my voice traffic 50% on queue 1 and the others just 10 10 and 30 for queues 2, 3, and 4. I used share instead of shape because I don't want to drop any traffic. Anyway, this setup works good even when I flood my T1 in both directions. All phone calls are jitter-free.
Anyway, hope this will help others.
