VoIP QoS for network with 4908G-L3, 3548Xl and 2900XL

[pfischer]

I have a star network, GBIC connections from 4908G-XL to 3 stacks with 3548XL and 2900XL's. Each stack has around 150 users with a Class-C and VLAN. I need to implement qos for VoIP. should be no problem on the 3548 and 2900's they support 802.1p, however I believe the 4908 does not. I think it only supports "IP precedence". How do I implement end-to-end QOS? Also I would like to run redundant GBIC connections between the 3548's in each closet. Do I have to change to a Class-B addressing and put all closets in the same subnet? Can I still have multiple VLAN's? thanks for help.

[murabi]

I guess you can not have end to end QoS in this case, as the CoS values will be lost when routed to 4908 L3 switch.

You may need a Cat6K in the place of 4908 if you need end to end QoS. Anyone disagrees with this thought?

http://www.cisco.com/en/US/products/hw/switches/ps606/products_qanda_item09186a00800a8922.shtml#Q21

[pfischer]

I think L2 COS values will be preserved as long as the frame does not change VLAN's while routed through the 4908. I am planning to put all the IP phones on a single VLAN, and PC's on different VLAN's. This way I will have L2 COS in the 2900 switches. But no QOS on the 4908. It shouldn't be a problem since these are GIG connections, and I don't have that much data trafic to oversubscribe the GIG links.

any comments?

[murabi]

This should work absolutely fine. I agree with you hunderd percent.

As long as the packets donot get routed, the COS will be preserved. So this must work.