Assign DHCP IPs for specific MAC prefixes on Windows Server 2008 R2
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.