Two DHCP scopes on one server

This is going to be a silly question, but this is the first time I've tried this, and it's not working.

I have a Windows 2008 R2 server configured as a DHCP server. It works fine with the existing scope setup for subnet 10.1.1.x/24. We recently got a new IP phone system,, and don't have enough IP's in this range for all of them, so my thought it to create a second scope of 10.1.2.x/24, and assign the phone to it.

I created the new scope on the existing DHCP server, and reserved all the phone MAC's an IP within this range. I then went onto the router/firewalll, a Sonicwall NSA 2400, and added this subnet to the existing port.

Then, we installed the new voicemail server, added it as 10.1.2.1. From any 10.1.1.x device, I can ping the voicemail server, and that 10.1.2.1 server can ping anything in the 10.1.1.x range.

Though, when turning on the phones, which are setup to gain IP's with DHCP, they don't take there assigned IP in the 10.1.2.x range, but an open 10.1.1.x IP address.

What am I missing to make this work?

Thanks.
pcteamadminAsked:
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Chris DentConnect With a Mentor PowerShell DeveloperCommented:
IP phones normally do it by claiming a separate VLAN. For example, Cisco phones use CDP (Cisco Discovery Protocol) to find the Voice VLAN prior to attempting to claim an IP. Since VLAN interfaces are separate on the router / firewall a relay is no problem. Obviously a lot there depends on your switches, firewalls and the phone system.

And since that's unlikely to help here. Can't you increase your range to 10.1.0.x/23 (covering 10.1.0.1 to 10.1.1.254 with a mask of 255.255.254.0)?

Chris
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BillBondoCommented:
I did something similiar where you need to enable dhcp forwarding?  on the router.
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BillBondoCommented:
Sorry, hit submit to quick. Anyway I had  a 172 and a 192 scope with the dhcp on the 172 side. It was relay agent but I am using 2003 server as a router.
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pcteamadminAuthor Commented:
I look at that too, but see on the Sonicwall that the IP helper only works if the two subnets are on different physical ports, which these are not.
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digitapCommented:
Some VoIP phones provide the ability for the workstations to connect to the network through the phone. Is this your case here or to the phones have their own physical connection to the network?

My thought here is to set an interface on the sonicwall for your voip traffic and have it route for you. This would facilitate BillBondo's solution of the DHCP forwarder.
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pcteamadminAuthor Commented:
The phone do not have there own physical connection. I wish they did. This wouldn't be any issue and voice traffic would be segregated.
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digitapCommented:
How are they connecting to the network?
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Wayne88Commented:
pcteamadmin,

i think your problem may be similar to this....see the dhcp explanation:

http://www.eggheadcafe.com/software/aspnet/31549250/multi-scope-dhcp.aspx
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pcteamadminAuthor Commented:
digitap, the pc nic's are plugged into the phones, the phones are into the switch, the switch into the router.

Starting to sound like I am going to have to expand this subnet to a class B instead of C, then I won't have this issue.

Will contact Sonicwall to see if it's possible to have a DHCP helper ip on the same physical port as the main subnet. Don't know if it would do anything or not.
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