Brocade Multi-Service IronWare Routing Configuration Guide (Supporting R05.6.00) - Manual (Page 100)

72 Multi-Service IronWare Routing Configuration Guide
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Adding a loopback interface
• If the device has loopback interfaces, the default device ID is the IP address 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 device ID is 10.9.9.9/24:
- Loopback interface 1, 10.9.9.9/24
- Loopback interface 2, 10.4.4.4/24
- Loopback interface 3, 10.1.1.1/24
• If the device does not have any loopback interfaces, the default device ID is the lowest
numbered IP interface address configured on the device.
NOTE
A device uses the same device ID for both OSPF and BGP4. If the device is already configured for
OSPF, you may want to use the device ID that already assigned to the device rather than set a new
one. To display the current device ID, enter the show ip CLI command at any CLI level.
To change the device ID, enter a command such as the following.
Brocade(config)# ip router-id 10.157.22.26
Syntax: [no] 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 device, but do not specify an IP address
that is being used by another device.
Adding a loopback interface
You can configure the device 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 device and
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 device. When you configure a BGP4 neighbor on the device, you can specify
whether the device uses the loopback interface to communicate with the neighbor. As long as a
path exists between the device and the neighbor, BGP4 information can be exchanged. The BGP4
session is not associated with a specific link, but is instead associated with the virtual interfaces.
NOTE
If you configure the device to use a loopback interface to communicate with a BGP4 neighbor, the
peer IP address on the remote device pointing to your loopback address must be configured.
To add a loopback interface, enter commands such as the following.
Brocade(config-bgp)# exit
Brocade(config)# int loopback 1
Brocade(config-lbif-1)# ip address 10.0.0.1/24
Syntax: [no] interface loopback num
The num value can be from 1 – 64.