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DHCP for nortel i200x phones on Nortel 5520 switches

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chrisgibo

Technical User
Nov 2, 2006
4
GB
I'm looking for some help in configuring some Nortel 5520 POE switches so that DHCP works for the Nortel Ip i200x phones.
What we have is 1 data vlan (vlan 21 - this is the default vlan on the switchports) and 3 voice vlans (100, 101 & 102). What I'd like to do is spread 400+ ip phones over the 3 class C voice vlan scopes. E.g. About 150 phones on each of the 200 addresses in each of the scopes on the voice subnets (we reserve some of the addresses in the subnet for future use/spares).

I've done some testing and I am struggling to get the spread of ip addresses across the vlans – all works fine if using 1 voice vlan, however can’t fit all the phones on 1 subnet without changing the mask. My idea to get the even spread of address was to split each of 48 port switches (12 switches in total) into 3 e.g ports 1-> 16 have a default vlan of 21 and then its capable of carrying just vlan 100 on the voice side. Ports 17 -> 32 have the default vlan 21 and the voice vlan 101 and finally the rest 33 -> 48 have the deafult 21 and voice vlan 102.
Thus I was hoping when I plugged an ip phone in it would go off to the dhcp server, get its temporary data vlan ip address with the list of voice vlans (used dhcp option 191 = VLAN-A:100,101,102.) Then drop the temporary address and request a new address but tag its packets the 1st voice vlan id. If the phones switch port is in vlan 100 it works ok and gets an ip address almost straight away. If however the phones switchport has either 101 or 102 it sits there for ages saying starting dhcp. I think it took around 10 mins for it to come up - however sometimes it didn't even come up but this may have been because I was using the same ip phone and moving it between switchports with the various voice vlan on them, thus there might have been an arp entry on the original address for it to confuse the matter.
What I'm wondering is if anyone has a similar setup using Nortel infrastructure and whether its possible to easily spread the phones across voice vlans.
Each voice vlan has a dhcp-relay entry for the dhcp server on it. If we send just one of the voice vlan ids in option 191, then the phone seems to get an address fine from that scope if the switchport carries the corresponding vlan.
We've done a very similar thing on cisco infrastructure at another site , where we’ve split the switchports up using the ‘switchport access vlan 17’ for data and assigned the ports ‘switchport voice vlan 156’ or ‘switchport voice vlan 157’ or ‘switchport voice vlan 158’ for voice. The ip phones get sent the same number of vlan ids from option 191, each voice vlan has an ip helper address of the dhcp server on it, however on the Cisco we can move phones around different switchports with different voice vlans and they get an ip address almost straight away. So as I’ve had very little experience on the Nortels I’m not sure how to configure them correctly.
The reason we want a spread of the phones across the vlans is in case there is a problem on one of the vlans (e.g. broadcast storm or some rouge device on it) then we don’t lose all the phones at the site.
Any help or advice would be most appreciated.
 
I understand what you're trying to do, but don't see an easy way to accomplish it.

As you're aware, when a phone is set to full DHCP/auto VLAN, the phone does a DHCP request on the native VLAN of the port (in your case, VLAN 21). The DHCP server responds with the information, the phone configures itself to tag the voice port to VLAN 100. No problem.

This could be easily accomplished if you had multiple data VLANs. But, with three voice VLANs and one data VLAN, I think you're out of luck.

An easy way, but not accomplishing what you want, is to configure the phones with their VLAN ID manually, but that could get to be a pain if people move their phones around a lot, unless all your ports are configured as potential members of any voice VLAN.

I'll be curious to see if anyone else has any other ideas. I've done installs with IP sets on different VLANs, but it's always been the "one data VLAN and one voice VLAN" per floor/building, etc. No problems in that scenario.
 
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