Design Option 4: Multihomed DHCP Servers
Applies To: Windows Server 2008
A multihomed DHCP server is one that provides DHCP service to more than one subnet. For a server to be multihomed, each network connection must attach the computer to a different physical network, which requires additional network adapters. Each adapter is configured to lease addresses on separate physical subnets.
Each network adapter is configured statically with a single IP address and each adapter connects the server to one of the three different physical subnets (A, B, and C). In this example, three scopes containing Class C ranges of IP addresses are used:
| Subnet | IP Address Range |
|---|---|
Subnet A |
192.168.0.1 - 192.168.0.254 |
Subnet B |
192.168.1.1 - 192.168.1.254 |
Subnet C |
192.168.2.1 - 192.168.2.254 |
Advantages
The advantage of a multihomed DHCP server design is that it does not rely on router forwarding support; it also does not need software-based relay agents. A single DHCP server can easily provide scopes for multiple subnets.
Disadvantages
The disadvantages of multihomed DHCP servers include:
Single point of failure: If the server becomes unavailable, multiple subnets will lose their DHCP support.
Administrative overhead: Multihomed DHCP servers are complex to set up and administer; incorrectly configured IP settings can lead to DHCP problems across the network.
Multiple network adapters required: Extra network adapters are required, and it is normally not possible to install more than three or four cards per server unless you use specialized (and expensive) server and network hardware.
See Also
Concepts
Design Options for DHCP on Routed Networks
Design Option 1: Multiple DHCP Servers
Design Option 2: BOOTP/DHCP Forwarding on Routers
Design Option 3: BOOTP/DHCP Relay Agents