Scope option 125

[johnlowe]

I am deploying a PBX with 200+ phones.
I know we can setup multiple scope option 125 with different subnets, how does this work?
What does the port in the switch that the 3300 connects to needs to be programmed as? Trunk port?

Thank you

[martyn]

The port doesn't need to be configured as a trunk, but you need to set up an IP helper on the other subnets that points to the controller.

The phone will then boot up in the other subnet and do a broadcast for an address. The router will then reply back that "it can help" it will then take the source mac address and convert it to a unicast request to the Mitel, which in turn will return an address.

[johnlowe]

What does the port needs to be program as? untagged voice lan?
What is IP helper? Is it a Mitel application?

[martyn]

Yes the port needs to be un-tagged on the voice vlan.

A brief explanation on IP helpers is here . I would suggest though that if you don't know what an IP helper is then you need to engage with a network engineer to make sure that this is set up correctly.