1140e DHCP and VLAN woes 2

[thepfy]

Hi Everyone,

We are having some issues with 1140e phones at a new site with DHCP and vlans.

The site has a CS1000 which is linked to another site which acts as the S2 if local CS1000 fails. The DHCP servers is a Windows 2008 R2 server and the switches are Cisco PoE models.

We have configured 2 separate VLANs for the phones and another for the PC's and we are using the DHCP option 191 to advertise the VLANs and option 128 (Nortel-i2004-A) to provide the S1 and S2 servers, ports and actions.

If we set the phone to be fully auto, with a voice vlan scope enabled and both DCHP options enabled. The phone waits on starting DHCP... Looking at the network diagnostic tools, it has correctly detected the voice VLAN and can see the correct advertisement options but it still has the PC VLAN address. However, the DHCP server lists the phone as having a lease in the Voice VLAN.

If we turn off the voice VLAN advertisement and disable the voice VLAN scope but leave the option 128 on, the phones work but are obviously in the wrong VLAN.

If I manually set the voice VLAN on the phone and have the voice VLAN scope enabled with the option 128 on, works correctly. The phone picks an address from the Voice VLAN and registers with the S1 server.

It seems to be an issue with either DHCP or the phones switching between the VLANs. The phone firmware doesn't seem to make a difference at it affects both phones out of the box and phones which have updated their firmware.

What is confusing us is we have copied the DHCP options from the sister site (except for the necessary change of VLAN number) where the phones register via DHCP correctly. On that site options 128 and 191 are advertised on the the data VLAN and the voice VLANs, suspect this isn't quite right.

Any ideas? Ideally I would like to just be able to plug in a phone and for it to work without any manual settings.

 

[Triton101]

not sure if you have gone through this doc, it might have some info, DHCP setup is provided as well as PVIDs for tagging and Vlan examples,

http://downloads.avaya.com/css/P8/documents/100099410

__________________________________________________________
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[ThephoneDude]

You didnt mention how the Cisco Data Switches were set up as for as DHCP relay /helper. But I had a similar problem a few years back. We went crazy for weeks trying to figure the problem out. After days of scrolling through wireshark traces between a good site and bad site we discovered the following:

DHCP relay was turned on and the data switch port that the DHCP server was plugged into had both the default vlan and the voice vlan assigned.

If we disabled DHCP relay or removed the voice vlan programming from the data switch port( the one used for DHCP server) the problem cleared. We opted to leave the DHCP relay intact and remove the voice vlan from the data switch port.

 

[Tman45]

Can you post your strings please? It could be something as simple as a semi-colon or period
We had an issue wirh our string and I think it didn't have a period at the end of the VLAN string

 

[thepfy]

Sorry for the delay in getting back to you. The DHCP strings were all fine. The switch port for the Windows DHCP server was set as a trunk port but the server was discarding the tagged replies from the phones. In Wireshark we could see constant DHCP requests and offers. Changing the switch port for the DHCP server to an access port resolved the issue.

Thanks for all the help and suggestions.

 

[curtismo]

Yep, having the voice VLAN on your DHCP server's interface will cause this problem that is hard to diagnose.