Need DHCP help

[km9v]

Hi,

I'm new here & new to Nortel & Voip. I have a couple of questions about setting up DCHP on Server 2003.  I have a large CS1000 w/ 5 branch offices & 11 SRG's. I'm using i2002 & i2004 phones. I have 16 different scopes to define b/c all have different subnets. My option 128 = Nortel-i2004-A,172.19.200.7:4100,1,10. which is the main CS IP. My VLANs = TLAN=10, ELAN=20, DATA=1. My PC workstations will plug into the phone & share the jack.

What options should I define in each scope?

[Michael McNamara]

Hi Km9v and welcome to the forums!

Your question is equivalent to "how do I get to the moon". We can certainly get you there but there are a lot of variables in play and while you've included some background there's more information required to really help give you any decent advice.

You probably already know that to be functional you need to at least pass the IP phones DHCP option 128 along with the standard options for any IP device (IP address, subnet mask, default gateway, etc). You mentioned the Nortel-i2004-A string so I'll stick with that and won't mention the Nortel-i2004-B string which may confuse you further. You have a fairly large configuration already in place so I'm not sure if you're experiencing a problem or you're just trying to understand how the voice reseller has deployed all this equipment.

You can easily configure each phone with all the necessary information (even the IP address) and have no reliance on DHCP or ADAC or LLDP, etc. The benefit in utilizing DHCP with ADAC/LLDP-MED is that you can standardize your IP phone configuration and let the network automatically assign the appropriate voice VLAN, IP address, QoS settings, port configurations, etc, without needing to involve an engineer.

While DHCP can be used to provide the voice VLAN to the IP phone it's not the preferred method these days with features such as ADAC and LLDP-MED available, this is especially true of large deployments. If you have under 50 IP phones it might certainly be easier for you to just statically configure each IP phone and call it a day. Unfortunately if you have 1000+ IP phones, with the usual adds/moves/changes a static configuration becomes very problematic. You can use DHCP option 191 (check out the second link below) to provide the IP phone the voice VLAN number - assuming your not statically configuring each IP phone with this information as mentioned above.

What network switches, brand and model, are you using to connect the IP phones? Nortel has a proprietary mechanism called ADAC (Automatic Detection Automatic Configuration) which when used with LLDP and LLDP-MED can provide the necessary voice VLAN and QoS information to the phone. Leaving DHCP to just provide option 128 along with the basic DHCP information. You can even provide the node number and TN information now via TFTP and the Nortel-i2004-B string (I won't go any further for fear of confusing you further).

While that probably doesn't answer your question hopefully it will give you some additional information on where you might go.

I would suggest you read the blog posts referenced below along with the comments.

Good Luck!

References;
 http://blog.michaelfmcnamara.com/2007/10/dhcp-options-voip/
 http://blog.michaelfmcnamara.com/2007/10/dhcp-options-voip-part-2/

[km9v]

Sorry for the delay in getting back to this thread. I have the following scope options set on all of the scopes: 002, 003, 128, 191 & 224. Each site is a different subnet. The switches are Cisco 3560s w/ PoE. The phones will also pass through workstation data. The PCs are static IP & on a different VLAN. The switches have all been configured by AT&T w/ VLANs VLAN tagging & QOS. They haven't' been much help in setting up Windows DHCP. I was wondering if there are any other scope or server options I should set in order to make phone swapping as simple as possible.

Thanks

[Michael McNamara]

If you are going to stick with DHCP (and it sounds like you are) you have everything you need.

You need to first return DHCP option 191 in the data VLAN. The phone will release that IP address and issue a DHCP request in the VLAN that was returned from option 191 (the voice VLAN). You should return DHCP option 128 or 224 in this VLAN to the phones.

You'll need to configure all your phones identically, disabling LLDP-MED, enabling Voice VLAN support and setting it to Automatic (if Voice VLAN is set to Automatic and LLDP-MED is disabled the phone will look to DHCP for Option 191).

As I mentioned previously there's a lot of information in those links, hopefully you've reviewed them.

Good Luck!