3.4 DHCP Superscopes

Superscope is an administrative feature of a DHCP server that can be used to group multiple scopes as a single administrative entity. Superscope allows a DHCP server to provide leases from more than one scope to clients on a single physical network. Scopes added to a superscope are called member scopes.

With this feature, a DHCP server can do the following:

  • 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, DHCP superscopes can be used to group and activate individual scope ranges of IP addresses used on the network. In this way, a DHCP server computer can provide leases from more than one scope to client on a single physical network.

Superscopes can resolve certain types of DHCP deployment issues for multinets, including the following situations:

  • 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. Another IP network range of addresses is needed 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 IP network range of addresses).

  • Two DHCP servers are wanted on the same physical network segment to manage separate logical IP networks.