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DHCP Option 125 in Data & Voice VLAN?

DHCP Option 125 in Data & Voice VLAN?

DHCP Option 125 in Data & Voice VLAN?

I have some older Extreme switches (ExtremeWare OS) that support LLDP but not enough to get the Mitel IP Phones to discover the Voice VLAN.  No problem - I have routing between the Data (access) & Voice VLAN so I'll configure Option 125 on both the Data & Voice VLAN DHCP Scopes.
Since LLDP is preferred (and usually supported in the switches) we normally just configure Option 125 globally on the DHCP server (so it automatically applies to all Scopes) and omit the 'vlan=xxx' part.  So I reconfigured Option 125 to include this for the Data VLAN but left the global settings (without 'vlan=xxx') in there for the Voice VLAN.
On bootup the phone uses Option 125 from the Data VLAN DHCP scope and begins tagging packets with the Voice VLAN tag, it leases a Voice VLAN IP address and displays it is using Option 125, however it displays 'TFTPerr' at the point it would normally start downloading and then resets.

I solved this by adding the same 'vlan=xxx' to the Voice VLAN DHCP scope but I kind of thought this was a bit odd as the phone should just ignore this option once it is speaking with a Tag?

Not a big issue but seems a little odd to me.  The Nortel (Avaya..) phones don't do this - they do a limited DHCP request on the access vlan and simply request an IP address and Option 128 (I think?) which tells it the Voice VLAN.  It then releases the IP address and sends out a more substantial DHCP request using Tagged frames, however it doesn't need to see the option telling it the Voice VLAN at this point.


RE: DHCP Option 125 in Data & Voice VLAN?

Option 125 on the data VLAN DHCP server only needs this entry - id:ipphone.mitel.com;vlan=X

This will give the phone the voice VLAN tag. The phone will then reboot tagged to the voice VLAN and request DHCP. The voice VLAN DHCP server needs options 3, 6 and 125. For option 125 use this example and change X to match your requirements. (call_srv & sw_tftp would be the IP address of the controller).


RE: DHCP Option 125 in Data & Voice VLAN?

OK.  So it still needs the 'vlan=xxx' in the Voice VLAN DHCP scope?  It just seems a bit odd as it has already accepted the Voice VLAN Tag from the Data VLAN DHCP scope?
I'll modify Option 125 for the Data & Voice VLANs when I get back to site and test.

Thanks, Andy

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