3560/3750 VoIP QoS

mattmullen · ‎06-10-2005

I have a working 3550 QoS configuration for Cisco IP phones that consists of the following:

3550 Global Configuration

mls qos

mls qos map cos-dscp 0 8 16 26 34 46 48 56

3550 IP Phone Ports

interface f0/1

mls qos trust cos

switchport voice vlan 2

switchport access vlan x (x = PC VLAN)

switchport priority extend cos 0

priority-queue out

wrr-queue cos-map 4 5

3550 Uplinks and router ports

interface f0/1

mls qos trust cos

mls qos trust dscp

priority-queue out

wrr-queue cos-map 4 5

I would like to apply the same logic in the configuration of 3560/3750 switches, however I am having trouble determining the equivalent configuration. From the Doc CD: http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3750/12225sea/3750scg/swqos.htm#wp1231446, it seems that I may be able to use the Auto QoS feature, but I am hesitant to use this due to not fully understanding all of the commands being entered into the switch. Is it common practice to apply the Auto QoS configuration and can it be trusted to work properly?

I noticed that when I applied the 'auto qos voip trust' command to an interface, it did not enable the 'priority-queue out' command to enable the priority queue on the interface. Shouldn't the priority queue be enabled just like it needs to be on the 3550?

If anyone has a working 3560/3750 QoS configuration for VoIP that you can post as an example, that would be great.

Thanks,

Matt

Chris Deren · ‎06-10-2005

The 3560 and 3750 will take the same configuration as 3550, the only difference is when you expedite the queue in 3550 the default queue is 4 which is CoS 6 and 7. In 3560 and 3750 the expedite queue is queue 1 which is CoS 5, DSCP 40-47. So no need for wrr-queue cos-map 4 5 on these swithces.

Refer to the follwowing:

3560- http://www.cisco.com/en/US/products/hw/switches/ps5528/products_configuration_guide_chapter09186a00802b7caf.html

3750-

http://www.cisco.com/en/US/products/hw/switches/ps5023/products_configuration_guide_chapter09186a00802c1100.html#wp1162303

Chris

aamercado · ‎07-10-2005

In the Qos SRND for the 3750, autoqos will auto set the cos/dscp maps on both ingress/egress but on Page2-59 the queuing /dropping recommend configs differ from those on auto-qos. What is the difference and which is better?

Thanks