System information

Configuring BGP
12-45
ip-address is the IP address of the BGP neighbor.
name is the name of the BGP peer group.
loopback indicates the interface type.
num is the loopback number; valid values are 1 to 16.
Example
Figure 12-15 shows a network that can benefit from the use of a loopback
interface, because an alternate path exists.
Routers New York and Albany are
running IBGP within AS 100. Router New York specifies the IP address of the
loopback interface (140.10.0.1) of Router Albany in the neighbor remote-as
command. Router Albany is configured to include the neighbor update-source
command so that the source of BGP TCP connections for the specified neighbor is the
IP address of the loopback interface instead on the IP address of a physical interface.
This eliminates the dependency on the physical interface. If a cable break occurs on
S0, the connection can still be maintained via S1, provided IP connectivity still exists
to the loopback.
Note: The loopback interface is unrelated to the IP loopback address
127.x.x.x.