Recall that a Cisco phone has this design:
PC <---> IP Phone <--> Switch SW1
^ The IP Phone acts as a mini-switch in its own right. It has three connections:
- The originating switch in the data closet
- A PC
- An internal connection to the phone for its OS and phone functions
We don't want to mix voice and data, so we need to separate them on two VLANs for easier QOS processing down the line. So, the phone goes on one VLAN and the PC goes on a different one. Also, recall that the phone may be powered via POE.
Configure the data center Switch:
SW1(config)#int g0/0
SW1(config-if)#switchport mode access
SW1(config-if)#switchport access vlan10
SW1(config-if)#switchport voice vlan 20
^ This set of commands configures int g0/0 not as a trunk port, but an access port that happens to allow two vlans on it - allowing both the phone and PC.
For POE:
power inline police
^ Configures power policing with default settings: if it draws too much power, disable the port and send a Syslog message.
Equivalent to:
power line police action err-disable
Kinder altnerative:
power line police action log
^ Logs but does not disable port.
[These are my notes from Jeremy's excellent CCNA course which can be viewed here.]
