ch makes certain assumptions about your network, and configures the switch accordingly. While I'm not a fan of letting network devices assume anything, in this case, the assumptions are accurate most of the time. I have had no qualms about enabling AutoQoS on the 3750s I've installed in VoIP networks with hundreds of phones supported by Cisco Call Manager. The reason I'm OK with this is that Cisco's assumptions are built around the idea that you're using Call Manager, Cisco IP phones, and low-latency queuing on your network. Chances are, if you need QoS enabled on your switches, it's because you're implementing VoIP. AutoQoS can be enabled on an interface with the auto qos voip command: 3750(config-if)# auto qos voip ? cisco-phone Trust the QoS marking of Cisco IP Phone cisco-softphone Trust the OoS marking of Cisco IP SoftPhone trust Trust the DSCP/CoS marking There are three options: cisco-phone, cisco-softphone, and trust. The first two are used for interfaces connected to either hard or soft phones. When configured with these options, the QoS values received in packets will be trusted only if they're sourced from Cisco IP phones. The trust option is used to enable QoS while trusting all packets' QoS values. If you'd like to see what AutoQoS does, enable AutoQoS debugging with the debug auto qos command before you configure the interface: 3750# debug auto qos 3750# conf t Enter configuration commands, one per line. End with CNTL/Z. 3750(config)# int g1/0/20 3750(config-if)# auto qos voip cisco-phone 750(config-if)# 3d04h: mls qos map cos-dscp 0 8 16 26 32 46 48 56 3d04h: mls qos 3d04h: no mls qos srr-queue input cos-map 3d04h: no mls qos srr-queue output cos-map 3d04h: mls qos srr-queue input cos-map queue 1 threshold 3 0 3d04h: mls qos srr-queue input cos-map queue 1 threshold 2 3d04h: mls qos srr-queue input cos-map queue 2 threshold 1 2 3d04h: mls qos srr-queue input cos-map queue 2 threshold 2 4 6 3d04h: mls qos srr-queue input cos-map queue 2 threshold 3 3d04h: mls qos srr-queue output cos-map queue 1 thr