DHCP server Second Subnet Vendor Based IP Allocation

Hi Experts
  We have a situation in which we are rolling out IP phones and the ip Phones require IP address in a different network as to the domain
the details are as follows

Domain network:
IP Phones Network:

We need to create a scenario where the dhcp allocates the addresses to the IP phones in the network
I was informed about the vendor class option in the DHCP options
The Vendor Mac Identifier is 00:15:65
Also if this requires configuring the option in ASCII or Binary how we do that....

Also we need to give a gateway of to the phones which i assume is just gateway option for that subnet but the main problem is to make the phones get ip in the

Also is it possible that the two networks can talk to each other if required in the future.

But we are having trouble implementing it
Could you please help us with the steps i need to follow as the setup is driving me nuts

*******Thanks to the experts in advance*******
Costas GeorgiouNetwork AdministratorAsked:
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Rob WilliamsConnect With a Mentor Commented:
I agree. Constantly we have small VoIP providers installing basic systems on an existing LAN. Over a 6 month period of complaints about sound quality, as Cliff stated, you eventually purchase the appropriate equipment to isolate and enforce QOS. Better to do it now.  Perhaps if your VoIP provider is not providing the proper equipment to configure the network, and misleading you with methods of implementing DHCP you should consider another provider.

However, to address your question. We can walk you through using Vendor Class ID's if you like, assuming your phone supports it, but static IP's or reservations are both faster to implement and far easier for an other IT person to understand what you have done. That is why you see so little documentation about Class ID's. Vendor Class ID's were primarily a server 2000 feature that was most often used for filtering/blocking network access. This was later replaced with a Microsoft 'tool'; the DHCP Server Callout DLL for MAC Address based filtering, which has now been completely replaced in server 2008 R2 with MAC filtering. If you have a Server 2008 R2 DHCP server you can now make use of filtering which should allow you to achieve what you want more easily, but only on server 2008 R2.  Server 2008 R2 allows to create a new scope, add a filter, and set allow for specific MAC addresses. The convenient feature is it allows wildcard MAC addresses. All of you phones are from the same manufacture so their MAC address should have the same Organizationally Unique Identifier (same first 3 octets). By using an allow filter for a MAC such as  A1-B2-C3-*-*-*  it should only assign DHCP scope options to a MAC meeting that filter requirement.
If I'm not mistaken, you can assign an IP to the MAC Address of the IP Phone.
Costas GeorgiouNetwork AdministratorAuthor Commented:
But to automate the process I m sure there is a way u can just configure the vendor identifier to automate the allocation to the devices from that vendor...
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Cliff GaliherConnect With a Mentor Commented:
The different gateway will still trip you up. If it were me I would isolate the networks. Either separate switches or at least VLANs, the you can set up a stock standard DHCP server on the second network. Then bridge the two networks, if necessary, with a router or layer 3 switch.

Costas GeorgiouNetwork AdministratorAuthor Commented:
But the problem is that the phone and pc share the network point and not cisco device option is available at this time....
Rob WilliamsConnect With a Mentor Commented:
I agree you definately should have the VoIP network separated from the PC's both for security and performance. Everybody today tries to install VoIP inexpensivly without installing the proper routing hardware.

As for a custom scope you are likly thinking of vendor and user class ID's with DHCP. You can create a second scope that uses vendor class ID's so that those scope options are applied to devices with a specific class ID, however that requires manually adding a identifiable class ID to each IP phone. Most phones do not have that option.
Using DHCP reservations would be much easier to configure, and maintain.
Costas GeorgiouNetwork AdministratorAuthor Commented:
The reson why we are trying the class if or vendor ID is becuse of the VOIP provider claming that they do it all the time, And not that we have asked them to do it for us, They are not able to do it....

So kind of they lied to us that they do it using vendor id and now they do seem to have a clue about it...

Please suggest what would be the appropriate setup for now....
Cliff GaliherCommented:
As previously stated, you REALLY should isolate VoIP traffic. Itnsolves your immediate problem, but also solves pain points you'll have in the future if you dont (dropped calls, sound quality, severe lag, etc).

If you don't have the drops and absolutely cannot run them (which, take my word for it, you eventually will do anyways to alleviate network related issues once deployment is live), just save time and statically set IP and gateway. That gateway issue will have you touching each device anyways, so setting an IP in addition is suddenly less of a big deal.

Costas GeorgiouNetwork AdministratorAuthor Commented:
Thanks for your support Guys
The provider apologized for providing misleading information and accepted that proper hardware, Vlan's and QOS is the right way to go ahead with the setup
Thanks Experts
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