Statement introduced before Junos OS Release 7.4.
Use the loopback interface, lo0, as the source address for all locally generated IP packets when the packet is sent through a routed interface, and also when the packet is sent through a local interface such as fxp0. The lo0 interface is the interface to the router's or switch's Routing Engine.
The default address is used as the source address for all locally generated IP packets on outgoing interfaces that are unnumbered. If an outgoing interface is numbered, the default address is chosen using the following sequence:
The primary address on the loopback interface lo0 that is not 127.0.0.1 is used.
The primary address for the primary interface or the preferred address (if configured) for the primary interface is used.
By default, the primary address on an interface is selected as the numerically lowest local address configured on the interface.
An interface’s primary address is used by default as the local address for broadcast and multicast packets sourced locally and sent out through the interface. An interface’s preferred address is the default local address used for packets sourced by the local router or switch to destinations on the subnet. By default, the numerically lowest local address configured for the interface is chosen as the preferred address on the subnet.
To configure a different primary address or preferred address, include the primary or preferred statement at the [edit interfaces interface-name unit logical-unit-number family family address address or [edit logical-systems logical-system-name interfaces interface-name unit logical-unit-number family family address address hierarchy levels.
For more information about default, primary, and preferred addresses for an interface, see “Configuring Default, Primary, and Preferred Addresses and Interfaces” in the Junos OS Network Interfaces Library for Routing Devices.
Required Privilege Level
system—To view this statement in the configuration.
system-control—To add this statement to the configuration.