Backup Router; Loopback Address; Built-In Ethernet Interface Address - Juniper J-series Services Router J2350 Hardware Manual

JUNOS Software with Enhanced Services Hardware Guide

Backup Router

You can specify a backup router to take over when the routing protocol process of
the Services Router is not running, usually when the Services Router is booting, or
if its routing protocol process has failed. Packets arriving at a Services Router in this
situation are routed to the backup router. When the routing protocol process starts
up again, the address of the backup router is removed from the routing and forwarding
tables of the Services Router. The backup router must be located on the same subnet.
NOTE: To configure a backup router, you must use the CLI or J-Web configuration
editor. You cannot configure a backup router with J-Web Quick Configuration.

Loopback Address

The loopback address is the IP address of the Services Router. The loopback address
ensures that the router provides an IP address to management applications. Because
it must always be available to hosts attempting to route packets to the router, the
loopback address resides on an interface that is always active, known as the loopback
interface (
packets addressed to the loopback address as long as the router is reachable though
any entry (ingress) interface. In addition, applications such as NTP, RADIUS, and
TACACS+ can use the loopback address as the source address for outgoing packets.
If you use the J-Web Set Up Quick Configuration page, you can either set a loopback
address of your choice or have the loopback address automatically set to
when you click Apply or OK to commit the configuration.

Built-In Ethernet Interface Address

The built-in Gigabit Ethernet interfaces,
panel of the Services Router, are the interfaces through which you perform initial
router setup. The examples in this guide use the
management interface, but you can use any built-in Ethernet port for management.
After the initial configuration is complete, you can attach the built-in Ethernet port
that you are using for management purposes to the management network.
Before initial configuration, when the factory default configuration is active, the router
attempts to perform autoinstallation by obtaining a router configuration through all
its connected interfaces, including
client out the built-in Ethernet interfaces.
If the Services Router does not find a DHCP server within a few seconds, it sets the
address of
interface.
NOTE: If the
94
Basic Connectivity Overview
). Setting a loopback address ensures that the router can receive
lo0.0
ge-0/0/0
to
ge-0/0/0 192.168.1.1/24
interface is being used, it is set to
ge-0/0/1
ge-0/0/0 through ge-0/0/3
interface as the
ge-0/0/0
. The Services Router acts as a DHCP
and becomes a DHCP server out the
192.168.2.1/24
127.0.0.1
, on the front
ge-0/0/0
.