[c-nsp] Re: 2950 QoS

[Jeremiah Millay]

This is what I use for Cisco IP phones with a 2950 switch. Please note 
that the phones set their CoS value as 5 by default (you can modify this 
in their configs).
I put the phones in the voice vlan (CDP must be enabled) and I set the 
ports to trust the cos of the phones. Portfast is enabled on the voice 
vlan by default but I have other devices connecting to the same port so 
I put portfast in there anyway. The switch supports four CoS queues for 
each egress port. For each queue, specify strict priority scheduleing 
(packets in the high priority queue always transmit first) or weighted 
round robin scheduling. Queue 4 is the expedite queue or strict priority 
queue while 1 - 3 are WRR. Notice how mine matches CoS value 5. This 
puts the phone in the priority queue. See my sample configs:

interface range fa0/2
 switchport voice vlan dot1p
 mls qos trust device cisco-phone
 mls qos trust cos
 spanning-tree portfast
!
wrr-queue cos-map 1 0 1 2 4
wrr-queue cos-map 3 3 6 7
wrr-queue cos-map 4 5

Some useful show commands:

show mls qos interface fa0/2
show wrr-queue cos-map
show wrr-queue bandwidth

Hope that helps.
Jeremiah


cisco-nsp-request at puck.nether.net wrote:

>Does anybody know what commands are necessary to enable layer2 QoS on a 
>2950?  I've read:
>http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12122ea5/2950scg/swqos.htm
>
>and it really doesn't help much.  I've got Cisco phones that are getting 
>tagged and I just want their traffic to have priority.  I've read that 
>"mls qos trust cos" will "trust" the QoS on ingress, but what about 
>egress?  I don't see anything about that and that's what I need.  Maybe 
>it's just on by default??  Thanks for any help.
>
>PA
>  
>
-- 
Rock River Internet                            Jeremiah Millay
202 W. State St, 8th Floor              jeremiah at rockriver.net
Rockford, IL 61101                      815-968-9888 Ext. 2202
USA                                               fax 968-6888