Understanding BGP Peering Sessions

To establish point-to-point connections between peer autonomous systems (ASs), you configure a BGP session on each interface of a point-to-point link. Generally, such sessions are made at network exit points with neighboring hosts outside the AS. Figure 26 shows an example of a BGP peering session.

In Figure 26, Router A is a gateway router for AS 3, and Router B is a gateway router for AS 10. For traffic internal to either AS, an IGP (OSPF, for instance) is used. To route traffic between peer ASs, a BGP session is used.

In addition to configuring BGP sessions between peering networks, you must also configure BGP internally to provide a means by which BGP route advertisements can be forwarded throughout the network. Because of the full mesh requirement of IBGP, you must configure individual peering sessions between all internal nodes of the network—unless you use route reflectors or confederations.

Related Topics

• Junos OS Feature Support Reference for SRX Series and J Series Devices
• BGP Overview
• Example: Configuring BGP Point-to-Point Peer Sessions
• Example: Configuring Internal BGP Peering Sessions