Configuring an Unnumbered Ethernet or Demux Interface

To configure an Ethernet or demultiplexing interface to be unnumbered, include the unnumbered-address statement in the configuration:

You can include this statement at the following hierarchy levels:

• [edit interfaces interface-name unit logical-unit-number family inet]
• [edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number family inet]

The unnumbered-address statement currently supports configuration of unnumbered Ethernet or unnumbered demux interfaces only for the IPv4 address family.

The interface that you configure to be unnumbered “borrows” an assigned IPv4 address from another interface, and is therefore referred to as the borrower interface. The interface from which the IP address is borrowed is referred to as the donor interface. In the unnumbered-address statement, interface-name specifies the donor interface. For an Ethernet unnumbered interface, the donor interface can be an Ethernet, ATM, SONET, or loopback interface that has a logical unit number and configured IP address and is not itself an unnumbered interface. For an IP demultiplexing unnumbered interface, the donor interface can be an Ethernet or loopback interface that has a logical unit number and configured IP address and is not itself an unnumbered interface. In addition, for either Ethernet or demux, the donor interface and the borrower interface must be members of the same routing instance and the same logical system.

When you configure an unnumbered Ethernet or demux interface, the IP address of the donor interface becomes the source address in packets generated by the unnumbered interface.

You can configure a host route that points to an unnumbered Ethernet or demux interface. For information about host routes, see the JUNOS MPLS Applications Configuration Guide.

For more information, see the following sections:

• Configuring a Preferred Source Address for Unnumbered Ethernet or Demux Interfaces
• Configuring Static Routes on Unnumbered Ethernet Interfaces
• Restrictions for Configuring Unnumbered Ethernet Interfaces
• Example: Configuring an Unnumbered Ethernet Interface
• Example: Configuring the Preferred Source Address for an Unnumbered Ethernet Interface
• Example: Configuring an Unnumbered Ethernet Interface as the Next Hop for a Static Route

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