Configuring IP Unnumbered on an Interface

In some scenarios, an interface can borrow an IP address from another interface to conserve IP addresses. For example, if an interface is seldom used, configure IP unnumbered on this interface so that the interface can share an IP address with another interface.

The restrictions for IP unnumbered interface configuration are as follows:

• The IP address to be borrowed cannot be a borrowed IP address.

• The IP address can be lent to multiple interfaces.

• If an interface has more than one IP address, IP unnumbered interfaces can borrow only the primary IP address.

• If the interface assigned to an IP unnumbered interface has no IP address, the IP unnumbered interface obtains the IP address 0.0.0.0.

• The interface that borrows an IP address cannot be an Ethernet interface.

• The IP address of the loopback interface can be lent to other interfaces, but the loopback interface cannot borrow an IP address from another interface.

An IP unnumbered interface can be configured on the S5720-EI, S5720-HI, S5720I-SI, S5720S-SI, S5720-SI, S5735-S, S5735S-S, S5735-S-I, S5730-HI, S5730S-EI, S5730-SI, S5731-H, S5731-S, S5731S-H, S5731S-S, S5732-H, S6720-EI, S6720-HI, S6720S-EI, S6720S-SI, S6720-SI, S6730-H, S6730S-H, S6730-S, and S6730S-S.