Configuring An Unnumbered Interface; Configuring An Unnumbered Point-To-Point Interface; Example: Configuring An Unnumbered Point-To-Point Interface; Configuring An Unnumbered Ethernet Or Demux Interface - Juniper JUNOS 10.1 - CONFIGURATION GUIDE 1-2010 Configuration Manual

JUNOS 10.1 Network Interfaces Configuration Guide

Configuring an Unnumbered Interface

When you need to conserve IP addresses, you can configure unnumbered interfaces.
Setting up an unnumbered interface enables IP processing on the interface without
assigning an explicit IP address to the interface. For IPv6, in which conserving
addresses is not a major concern, you can configure unnumbered interfaces to share
the same subnet across multiple interfaces. IPv6 unnumbered interfaces are only
supported on Ethernet interfaces. The statements you use to configure an unnumbered
interface depend on the type of interface you are configuring: a point-to-point interface
or an Ethernet interface:

Configuring an Unnumbered Point-to-Point Interface

To configure an unnumbered point-to-point interface, configure the protocol family,
but do not include the
You can include this statement at the following hierarchy levels:
NOTE: For interfaces with PPP encapsulation, you can configure an unnumbered
interface by including the
more information, see "Configuring IPCP Options" on page 189.
When configuring unnumbered interfaces, you must ensure that a source address is
configured on some interface in the router. This address is the default address. We
recommend that you do this by assigning an address to the loopback interface (
as described in "Configuring the Loopback Interface" on page 263. If you configure
an address (other than a martian) on 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 Point-to-Point Interface

Configure an unnumbered point-to-point interface:
192
Configuring an Unnumbered Interface
Configuring an Unnumbered Point-to-Point Interface on page 192
Configuring an Unnumbered Ethernet or Demux Interface on page 193
address
family family;
[edit interfaces interface-name unit logical-unit-number]
[edit logical-systems logical-system-name interfaces interface-name unit
logical-unit-number]
unnumbered-interface
[edit]
interfaces {
so-6/1/0 {
unit 0 {
family inet;
family iso;
statement:
statement in the configuration. For
interface, that address is always the
lo0
lo0 ),