Configuration Guide User guide

1354 FastIron Configuration Guide
53-1002494-02
Basic configuration tasks required for BGP4
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.
You can add up to 24 IP addresses to each loopback interface.
NOTE
If you configure the Brocade Layer 3 switch 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 those shown in the following example.
Brocade(config-bgp-router)#exit
Brocade(config)#int loopback 1
Brocade(config-lbif-1)#ip address 10.0.0.1/24
Syntax: interface loopback <num>
The <num> value can be from 1 through 8 on Chassis Layer 3 switches. The value can be from 1
through 4 on the Compact Layer 3 switch.
Adding BGP4 neighbors
The BGP4 protocol does not contain a peer discovery process. Therefore, for each of the router
BGP4 neighbors (peers), you must indicate the neighbor IP address and the AS each neighbor is in.
Neighbors that are in different autonomous systems communicate using EBGP. Neighbors within
the same AS communicate using IBGP.
NOTE
If the Layer 3 switch has multiple neighbors with similar attributes, you can simplify configuration by
configuring a peer group, then adding individual neighbors to it. The configuration steps are similar,
except you specify a peer group name instead of a neighbor IP address when configuring the
neighbor parameters, then add individual neighbors to the peer group. Refer to “Adding a BGP4 peer
group” on page 1361.
NOTE
The Layer 3 switch attempts to establish a BGP4 session with a neighbor as soon as you enter a
command specifying the neighbor IP address. If you want to completely configure the neighbor
parameters before the Layer 3 switch establishes a session with the neighbor, you can
administratively shut down the neighbor. Refer to “Administratively shutting down a session with a
BGP4 neighbor” on page 1364.
To add a BGP4 neighbor with IP address 209.157.22.26, enter the following command.
Brocade(config-bgp-router)#neighbor 209.157.22.26
The neighbor <ip-addr> must be a valid IP address.
The neighbor command has some additional parameters, as shown in the following syntax:
Syntax: [no] neighbor <ip-addr> | <peer-group-name>
[advertisement-interval <num>]