Configuring BGP

When the BGP protocol instance is created, the no shutdown command is not required because BGP is administratively enabled upon creation. Minimally, to enable BGP on a router, you must associate an autonomous system number for the router, have a preconfigured router ID or system interface, create a peer group, neighbor, and associate a peer ASN. There are no default groups or neighbors. Each group and neighbor must be explicitly configured.

All parameters configured for BGP are applied to the group and are inherited by each peer, but a group parameter can be overridden on a specific basis. BGP command hierarchy consists of three levels:

The global level
The group level
The neighbor level

 config>router# bgp (global level)
         group (group level)
             neighbor (neighbor level)

Note:

Careful planning is essential to implement commands that can affect the behavior of global, group, and neighbor levels. Because the BGP commands are hierarchical, analyze the values that can disable features on a particular level.

Example: Basic BGP configuration output

ALA-B>config>router# info 
#------------------------------------------
# BGP Configuration
#------------------------------------------
#------------------------------------------
# BGP
#------------------------------------------

        bgp
        exit

#------------------------------------------
ALA-B>config>router#