Voice and Data Vlans

[Malcolm2]

I need to setup a switch (X460P) to be able to use a VOIP Phone (Polycom) and to be able to use a PC also. The PC MIGHT be plugged into the phone, or there may not be a phone at all, just a PC plugged into a port.

All ports on the switch would need this ability.
So far, I would do this:
Create Vlan Voice tag 10
Config Voice IPAddress 192.168.102.2/24
Config voice add ports 1-48 tag
config vlan default ipaddress 192.168.100.2/24
config vlan default add ports 1-48
ena ipforward voice
ena ipforward default
Config iproute add default 192.168.100.250

I would configure DHCP for each vlan

Now comes my real question.
How does the switch know that I'm plugging in a phone, rather than a PC (or printer or other device). ? I want the voice vlan to get DHCP from the scope I create for Voice, but if a PC gets plugged in, I want DHCP from the data scope I create.
How it know?

[McClane]

Depending on the Polycom model, you should be able to use LLDP to assign the VLAN ID... I would search through Polycom documentation and verify their LLDP support and then read through the LLDP section of the EXOS user guide.

[Patrick_Voss]

It knows based off the tagging of the port. A PC will not send tagged traffic therefore it will be received on the untag VLAN of that port. Depending on how a phone is configure it should pass tagged traffic. Depending on the phone it should default tagged.