IP phones across multiple voice VLANs

[teekow]

I will be using DHCP Voice VLAN Auto-Discovery to boot up my IP phones and automatically assign the Voice VLAN ID to my phones.

Does anyone know what will happen if/when I need to move an IP phone from one Voice VLAN subnet to a different Voice VLAN subnet? My fear is that once I am in Voice VLAN ID 100 and then move to an area of the building that is not a part of that VLAN I will never get a response to my DHCP discovery.

Am I thinking correctly that on a reboot,the DHCP discovery goes out on the Voice VLAN? Or, will it receive no DHCP Offer and then be smart enough to send a new discovery on the native.

I will eventually know the answer, but right now I am in the design stage and don't have a lab that I can test this particular scenario in.

Any thoughts?
Rob

 

[bignose21]

I think I'm right in thinking phone initial gets Data Lan address then DHCP assigns correct VLAN ID and IP. We did a site that has about 800 users and the VLANs were locked down to about 150 address per LAN that was on full DHCP.

 

[guycable2]

I would bet that if you have the Cached IP set that it won't work. Stickiness could be a factor to. I should have a test enviroment setup to try this soon. I'm curious too as that could be a factor here.

 

[ansellrk]

We move phones all the time over multiple voice VLANS and there are no problems, it picks up a new IP address from the local DHCP scope - We always create new phones in our local office and then take them out to site so I know this works as we are rolling out 1200 phones at the moment!

With ADAC & LLDP you can actually bypass the "get an address from data scope, drop it and then get one from voice scope" option. You can also add loads of different DHCP options into your scope with the very latest firmware released from Nortel (May 2008). This firware allows you to change lock options, enable DIM options, turn ADAC on/off, set ports to 10/100/1000, set autonegotiate on, etc, etc.

Rob