BGP and Autonomous Systems

Border Gateway Protocol

• Set of rules to determine best path to destination

• Uses mechanism called peering

• Each BGP peer sits at the edge of Autonomous systems

• Each BGP peer participates in Route discovery, Route storage and Route Selection

• Each BGP peer knows about it's neighbor

• Each BGP peer collection information such as latency, hop count, cost of transmission

Autonomous Systems

• Autonomous systems use BGP

• Each AS is a distinct network that broadcasts how it can be reached

• Information provided by AS is then used by other AS on the internet to decide how to best route a packet going to specific destinations

• AS can be an ISP or network of organization

• Each AS has a unique identifier

• AS have their own rules of governance to decide how packets get routed within the network