DHCP Option 43

[lundah]

I can't for the life of me get DHCP option 43 working using a Windows 2019 server for either 5300 or 6900 series sets. Following the attached guide which I got from KMS, but the phones just aren't accepting the offer from the Windows DHCP server. Trying to migrate away from using an MXE-III controller as my DHCP server for 1700 phones, too many single points of failure on it. The Windows server is the DHCP server for everything but the VoIP subnets. I'm sure I'm missing something stupid,. but I can't figure out what.

[Kal99]

You could  try option 125?   I have only ever had option 43 fail when the firmware on the phones was old.  I had to put them in TW mode upgrade the units and then default them and then it took option 43.

[lundah]

I'd do Option 125 if I could figure out where to add it. I see a pre-defined list of options, 43 is in there, but 125 is not and I see no method to add one.

Might have been a network switch config issue, network guy changed something and now it's working. Now to figure out what he did.

[ZuluAlpha]

I have to have network change DHCP helpers for the voice VLAN from the MXE to the windows server when I do similar changes.

[lundah]

My test switchport was configured with the same VLAN for both the voice and data VLAN on that port, which the phone did not like. Once we switched it to a "normal" config with the test VLAN as voice and the live data VLAN as the default access VLAN, it came right up.

My voice subnets are large enough that I was able to split them up between the existing DHCP server on the controller and add a unique range within the same subnet on the Windows DHCP server, which in turn has failover set up to a backup server. The subnets are /16, and the existing pools were the first /22 within that subnet, so I just added the next /22 as the pool for Windows DHCP. The phone will grab the offer it receives first, so now I've got some redundancy.