Building Peering Sessions
This example demonstrates the different types of BGP peering sessions you will encounter. Consider Figure 11-1.
Figure 11-1. Building Peering Sessions
An IBGP peering session is formed within AS3, between RTA's loopback address and RTF's physical address. EBGP sessions are also formed between AS3 and AS1 by using the two directly connected IP addresses of RTA and RTC. Another EBGP session is formed between RTF in AS3 and RTD in AS2, using IP addresses that are not on the same segment (multihop).
It is important to remember that the BGP TCP connection will not become established unless there is IGP connectivity ...