6509 Qos

[tdhaliwal]

I have a core 6509 with msfc doing layer 3 routing. and access 6509 switch with pfc and that has ip phones plugged into it. the phone send dscp ef. Can the access layer trust dscp and send it through the network because it has pfc.

[tsettle]

Yes. All you need on the cat6k for L3 QoS is the PFC card. Therefore, as you have described your systems as having a PFC, you can trust incoming DSCP. Remember that if the phone is connected to a 6248 or 6348 then you will need to use an QoS ACL to trust the DSCP vs using the port trust state. Also, you will need to trust DSCP for the entire path of the VoIP packets (ie all switches) not just at ingress (phone port). Here are the links for Documentation:

For Hybrid Mode

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/sw_8_1/confg_gd/qos.htm

For Native Mode

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/12_1e/swconfig/qos.htm

Tech Tips

http://www.cisco.com/pcgi-bin/Support/browse/psp_view.pl?p=Hardware:Catalyst_6500_Series_Switches&viewall=true

[peter.scott]

It maybe well worth noting, that if you want to use the priority receive queue, then you would have to set the port to trust-cos, and then let the PFC derive the DSCP value from the mappings. If you use anything other that trust-cos, then you would only be using one receive queue.