A superscope is an administrative feature of Dynamic Host Configuration Protocol (DHCP) servers running Windows Server 2008 that you can create and manage by using the DHCP Microsoft Management Console (MMC) snap-in. By using a superscope, you can group multiple scopes as a single administrative entity. With this feature, a DHCP server can:
Support DHCP clients on a single physical network segment (such as a single Ethernet LAN segment) where multiple logical IP networks are used. When more than one logical IP network is used on each physical subnet or network, such configurations are often called multinets.
Support remote DHCP clients located on the far side of DHCP and BOOTP relay agents (where the network on the far side of the relay agent uses multinets).
In multinet configurations, you can use DHCP superscopes to group and activate individual scope ranges of IP addresses used on your network. In this way, the DHCP server can activate and provide leases from more than one scope to clients on a single physical network.
Superscopes can resolve specific types of DHCP deployment issues for multinets, including situations in which:
The available address pool for a currently active scope is nearly depleted, and more computers need to be added to the network. The original scope includes the full addressable range for a single IP network of a specified address class. You need to use another range of IP addresses to extend the address space for the same physical network segment.
Clients must be migrated over time to a new scope (such as to renumber the current IP network from an address range used in an existing active scope to a new scope that contains another range of IP addresses).
You want to use two DHCP servers on the same physical network segment to manage separate logical IP networks.
Superscope configurations for multinets
The following section shows how a simple DHCP network consisting originally of one physical network segment and one DHCP server can be extended to use superscopes for support of multinet configurations.
Example 1: Non-routed DHCP server (before superscope)
In this example, a small local area network (LAN) with one DHCP server supports a single physical subnet, Subnet A. The DHCP server in this configuration is limited to leasing addresses to clients on this same physical subnet.
The following illustration shows this example network in its original state. At this point, no superscopes have been added and a single scope, Scope 1, is used to service all DHCP clients on Subnet A.
Example 2: Superscope for non-routed DHCP server supporting local multinets
To include multinets implemented for client computers on Subnet A, the same network segment where the DHCP server is located, you can configure a superscope that includes as members the original scope (Scope 1) and additional scopes for the logical multinets for which you need to add support (Scope 2 and Scope 3).
This illustration shows the scope and superscope configuration to support the multinets on the same physical network (Subnet A) as the DHCP server.
Example 3: Superscope for routed DHCP server with relay agent supporting remote multinets
To include multinets implemented for client computers on Subnet B, the remote network segment located across a router from the DHCP server on Subnet A, you can configure a superscope that includes as members the additional scopes for the logical multinets for which you need to add remote support (Scope 2 and Scope 3).
Because the multinets are for the remote network (Subnet B), the original scope (Scope 1) does not need to be part of the added superscope.
This illustration shows the scope and superscope configuration to support the multinets on the remote physical network (Subnet B) away from the DHCP server. A DHCP relay agent is used for DHCP servers to support clients on remote subnets.
Create a superscope
You can use this procedure to create a DHCP superscope.
Membership in the Administrators or DHCP Administrators group is the minimum required to complete this procedure.
|To create a superscope|
Open the DHCP snap-in.
In the console tree, click the DHCP server you want to configure.
On the Action menu, click New Superscope.
This menu option only appears if at least one scope that is not currently part of a superscope has been created at the DHCP server.
Follow the instructions in the New Superscope Wizard.