I'm running Windows Server 2008 R2 for my DHCP server. We are about to switch over to a VoIP system and Cisco VoIP phones. I would like to assign a specific range of IPs to these phones which will have a common MAC prefix (ex. 00:01:02). I would prefer to have them in the same scope as our computers if possible. Does anyone have any suggestions?

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    Why do you want them in the same scope? Isn't the 'best practice', to have VoIP devices on a separate VLAN? – Zoredache May 10 '11 at 20:53
  • Cisco viop phones aren't easy to coexist on the same segment with "regular" traffic. Try looking at lync compatible phones instead as QOS and co-existance was designed from the get-go – Jim B May 11 '11 at 0:36
  • @zoredache - I've read articles going both ways, some saying it's imparitive to seperate the two, others saying the duplication of everything isn't worth the hassle, plus when the two systems need to communicate it complicates things. So I was opting for putting them together. – Daniel B May 11 '11 at 16:01
  • @Jim B - I appreciate the advice, but I've already committed to the phones and virtual PBX. – Daniel B May 11 '11 at 16:02

You can use reservations to map specific IP addresses to specific MAC addresses, but there is no way to select a range of addresses (or even a scope) based only on the MAC prefix. I would suggest you place those devices on a separate network segment (physical or VLAN) and use a DHCP scope for that; this will also come a lot handy if/when you want to apply firewall and/or QoS policies to those devices.

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    I was afraid that would be the answer. I think I'll end up going with a new physical network segment. I've been reading that with VOIP traffic that is a safer route to take. – Daniel B May 10 '11 at 21:20
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    Argh. I had this working perfectly with ISC's DHCP3 daemon on our Linux DHCP server. It assigned a DHCP pool based on a substring match of the MAC address. Now we're setting up SBS 2011, and I find that Windows Server doesn't support this. Thanks for comfirming my fears :-) – Martijn Heemels Nov 22 '11 at 15:28

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