Brocade BigIron RX Series Configuration Guide - Manual (Page 944)

866 BigIron RX Series Configuration Guide
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Adding a loopback interface
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• If the router has loopback interfaces, the default router ID is the IP address configured on the
lowest numbered loopback interface configured on the device. For example, if you configure
loopback interfaces 1, 2, and 3 as follows, the default router ID is 9.9.9.9/24:
• Loopback interface 1, 9.9.9.9/24
• Loopback interface 2, 4.4.4.4/24
• Loopback interface 3, 1.1.1.1/24
• If the device does not have any loopback interfaces, the default router ID is the lowest
numbered IP interface address configured on the device.
NOTE
A BigIron RX uses the same router ID for both OSPF and BGP4. If the router is already configured for
OSPF, you may want to use the router ID that is already in use on the router rather than set a new
one. To display the router ID, enter the show ip CLI command at any CLI level.
To change the router ID, enter a command such as the following.
BigIron RX(config)# ip router-id 209.157.22.26
Syntax: ip router-id <ip-addr>
The <ip-addr> can be any valid, unique IP address.
NOTE
You can specify an IP address used for an interface on the BigIron RX, but do not specify an IP
address in use by another device.
Adding a loopback interface
You can configure the router to use a loopback interface instead of a specific port or virtual routing
interface to communicate with a BGP4 neighbor. A loopback interface adds stability to the network
by working around route flap problems that can occur due to unstable links between the router and
its neighbors.
Loopback interfaces are always up, regardless of the states of physical interfaces. Loopback
interfaces are especially useful for IBGP neighbors (neighbors in the same AS) that are multiple
hops away from the router. When you configure a BGP4 neighbor on the router, you can specify
whether the router uses the loopback interface to communicate with the neighbor. As long as a
path exists between the router and its neighbor, BGP4 information can be exchanged. The BGP4
session is not associated with a specific link but instead is associated with the virtual interfaces.
NOTE
If you configure the BigIron RX to use a loopback interface to communicate with a BGP4 neighbor,
the peer IP address on the remote router pointing to your loopback address must be configured.
To add a loopback interface, enter commands such as the following.
BigIron RX(config-bgp)# exit
BigIron RX(config)# int loopback 1
BigIron RX(config-lbif-1)# ip address 10.0.0.1/24
Syntax: interface loopback <num>
The <num> value can be from 1 – 8.