k to 3750 ] R1-PBX(config-if)# no ip address R1-PBX(config-if)# duplex full R1-PBX(config-if)# speed 100 Next, we'll configure the subinterface for VLAN 901, the data VLAN: R1-PBX(config-if)#interface FastEtherneto/0.901 R1-PBX(config-subif)# description [ Data ] R1-PBX(config-subif)# encapsulation dot1Q 901 R1-PBX(config-subif)# ip address 192.168.1.1 255.255.255.0 Finally, we'll configure the subinterface for the voice VLAN: R1-PBX(config-subif)#interface FastEtherneto/0.902 R1-PBX(config-subif)# description [ Voice ] R1-PBX(config-subif)# encapsulation dot1Q 902 R1-PBX(config-subif)# ip address 192.168.2.1 255.255.255.0 None of this may seem to have anything to do with VoIP, and while that may be true, it's important to understand that we're trunking to the router and using Ethernet sub- interfaces to do SO. Alternatively, I could have made VLAN 901 the native VLAN and only configured the voice VLAN as a dot1q subinterface. You may have noticed that the VLAN design shows the phones in one VLAN and workstations in another, yet the physical drawing shows the PCs connecting to the phones. The key thing to understand here is that the Cisco phones I'm using have two- port switches built into them. They will connect to the switch with a trunk containing both VLANs. The PCs will connect to the phone on the other port. The phone will grant access to the PC on the data VLAN, while the phones will communicate on the voice VLAN. The phone ports are illustrated in Figure 30-3. This behavior is configu- rable in all sorts of interesting ways, but we'll stick with the standard. Chapter 30: VolP 2811 w/CME Trunk Trunk VLANs 902 VLANs 901 & 902 VLANs 901 & 902 Figure 30-3. Cisco IP phone and workstation connectivity Switch Ports Since the phones will connect to the switch via trunks, let's configure the interfaces on the 3750 that will have phones attached. I've reserved interfaces 1-9 on the switch for phones. Using the interface range command, we'll configure them all at once: SW-3750(config)#int range g1/0/1 - 9 SW-3750(co