Polycom getting DCHP address from wrong VLAN

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I have been tearing my hair out on this issue for 2 days, any help
would be appreciated.

We have a normal network and a Cisco SGE2010P switch – a 48 port PoE switch

There are two VLANs, 1(data) & 50(VoIP). When Polycoms are connected
to the switch with VLAN 50 hard coded in the config they grab a DHCP
address from VLAN 1, the PVID for the switch port.

The ports have membership in VLAN 1 as the PVID and VLAN 50 as tagged
traffic. I know the VoIP DHCP server is working because if I change a
port to have a PVID of 50 any device gets the address from the VoIP
DHCP server.

I have tried the ports as ‘general’ and ‘trunk’ with no success.

Any help would be greatly appreciated, I don’t have much hair left!

3 thoughts on - Polycom getting DCHP address from wrong VLAN

  • That switch doesn’t seem to support CDP, so the Polycom phone has no way of figuring out which VLAN to tag itself to “automagically”. It will grab the primary VLAN unless you specify otherwise in the phone’s setup.

    On boot of the phone, go into setup, default password 456, there’s an option in there to specify the VLAN ID. You can force your VLAN 50. Should bring you up.

    If your switch had done CDP (such as some higher end switches), the phone tells the switch “Im a phone” and the switch has a voice-vlan configuration which would then push that VLAN to the Polycom. We did this kind of setup in a large scale (100+) installation.


  • One more thing: Make sure that the port going to your data-DHCP server doesn’t have the voice VLAN set on it. I troubleshot an installation for a few hours before thinking of this…


  • Interesting, the DHCP server for the voice and data are coming from
    the same router. The router connects to the switch via a trunk port.

    I will set up a dedicated DHCP server on a port with a PVID of 50.

    Thanks for the tip!