Configuring an Unnumbered Interface

When you need to conserve IP addresses, you can configure unnumbered interfaces. To do this, configure the protocol family, but do not include the address statement:

family family; 

You can include this statement at the following hierarchy levels:

• [edit interfaces interface-name unit logical-unit-number]
• [edit logical-routers logical-router-name interfaces interface-name unit logical-unit-number]
  

  NOTE: For interfaces with PPP encapsulation, you can configure an unnumbered interface by including the unnumbered-interface statement in the configuration. For more information, see Configuring IPCP Options.

  
  

When configuring unnumbered interfaces, you must ensure that a source address is configured on some interface in the routing platform. This address is the default address. We recommend that you do this by assigning an address to the loopback interface (lo0), as described in Configuring the Loopback Interface. If you configure an address (other than a martian) on the lo0 interface, that address is always the default address, which is preferable because the loopback interface is independent of any physical interfaces and therefore is always accessible.

Example: Configuring an Unnumbered Interface

Configure an unnumbered interface:

[edit]

interfaces {

    so-6/1/0 {

        unit 0 {

            family inet;

            family iso;

        }

    }

}