Interior Border Gateway Protocol (IBGP) is a routing protocol used within an autonomous system (AS) to exchange routing information between routers within the same AS. IBGP ensures that all routers in an AS have a consistent view of the network topology, allowing for efficient communication and routing decisions within the AS. Unlike External BGP (EBGP), which exchanges routing information between different ASs, IBGP is used to propagate routes within a single AS.
Some key points about IBGP include:
- It requires a full mesh topology where every router must be fully meshed with every other router in the same AS.
- Path attributes are propagated unchanged from one IBGP peer to another, and the AS path attribute is not modified.
- By using route reflectors or configuring next-hop-self, routers can overcome limitations related to route advertisement and loop prevention.
- It allows for more efficient routing within an AS, provides redundancy and failover capabilities, and helps prevent routing loops.
In summary, IBGP plays a crucial role in facilitating communication between routers within an AS, ensuring consistent routing information, and enabling efficient data transfer within a network.