AS-number— AS number used with EBGP neighbors.
1_or_more_AS-numbers— AS number(s) of directly connected peers that are in a different sub-AS.
Purpose: IBGP neighbors do not propagate routing information learned from one IBGP neighbor to another IBGP neighbor. If you are running IBGP, every IBGP speaker must have a connection to every other IBGP speaker in the AS. This becomes a scaling problem as the number of IBGP speakers increases. The number of IBGP connections for n speakers is [n(n–1)]/2. Table 3-1 lists the number of connections needed for two to ten IBGP speakers.
|Number of IBGP Speakers||Number of Connections|