nfig-if-range)# description [ IP-Phone ] SW-3750(config-if-range)# switchport trunk encapsulation dot1q SW-3750(config-if-range)# switchport trunk native vlan 901 SW-3750(config-if-range) switchport mode trunk SW-3750(config-if-range)# switchport nonegotiate SW-3750(config-if-range)# switchport voice vlan 902 SW-3750(config-if-range)# spanning-tree portfast Additionally, every port that has a Cisco IP phone should have QoS configured such that the switch will trust marked packets originating from the phone. We do this with the auto qos interface command. There are a few options as shown below. Choose the proper one based on the device connected: SW-3750(config-if-range)#auto qos voip ? cisco-phone Trust the QoS marking of Cisco IP Phone cisco-softphone Trust the QoS marking of Cisco IP SoftPhone trust Trust the DSCP/CoS marking Since I'm using all Cisco IP phones, I'll use the cisco-phone option: SW-3750(config-if-range)#auto qos voip cisco-phone If you enter this command after you've already connected your phones, you'll get out- put similar to this: 1w3d: %SWITCH_Q0S_TB-5-TRUST_DEVICE_DETECTED cisco-phone detected on port Gi1/0/1, port's configured trust state is now operational. Don't be surprised if you see a full page of mls qos commands the next time you view your running config. On my switch, it added 45 or SO ugly commands right at the top of the config SO that you have to page by them to see anything else. See Chapter 19 for an example. Enabling AutoQoS also polluted the configuration of each phone interface with the following additions: srr-queue bandwidth share 10 10 60 20 srr-queue bandwidth shape 10 0 0 0 queue-set 2 Small-Office VolP Example mls qos trust device cisco-phone mls qos trust cos auto qos voip cisco-phone Sure, it's ugly, but when it comes to VoIP, QoS should not be ignored. As far as the 3750 is concerned, we're pretty much done. The only thing left would be to configure a VLAN and interfaces for the outside network between the router and the firewall. Since that's not strictly VoIP-rel