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IP Phone VLAN Assignment

Dear all,

I just want to verify that I am understanding the VLAN settings for an IP phone correctly, with a few examples:

I understand that  the use of a voice VLAN together with CDP or LLDP is the recommended way of working for assigning VLAN's automatically.

But I want to understand the other option's better.

1) I have a basic SOHO switch with only VLAN's so no CDP or LLDP. All interfaces are assigned to 'default' VLAN 1 untagged, a DHCP server is also connected to a port in VLAN 13.

My phone is a 7945 for example, brand new out of the box.

If I connect the phone, he will just come up on this untagged VLAN and get an IP address from the DHCP server, just similar as a regular PC would?

2) same situation as in 1), but now I also connect a PC to the phone's internal switch, will the phone's switch just pass the traffic to the PC by default as would be the case with a regular switch. So in this case I will end up with the PC, phone, and other devices connected to the switch on 1 VLAN (VLAN 1 in this case)

3) I create a 2nd VLAN on the switch (VLAN 2) which will be used for voice. On the port connected to the phone I create a 802.1Q trunk with VLAN 1 as the native VLAN (untagged) and VLAN 2 as tagged. Still my switch does not support CDP or LLDP.

- The phone boots and will get a IP address in VLAN 1 again as was the case before the creation of the trunk?

- I need to manually configure the Admin VLAN ID to VLAN 2?

- The PC VLAN option stays empty since it is untagged?

- After a reboot the phone comes back up and receives a IP in VLAN 2, and the untagged traffic is forwarded to the PC connected to the Phone's internal switch?

Thanks in advance


IP Phone VLAN Assignment


1) Yes the ip phone will receive ip address from the dhcp server (remember the option 150 on your scope to indicate the TFTP server)

2) Yes the PC will receice traffic through PC port

3) If your switch does not support LLDP , you have to manually modify the admin VLAN on the IP Phone. The PC Vlan will be the native vlan on the trunk.




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