BGP
Key Points
- Used for inter-domain routing between autonomous systems
- Supports policy-based route exchange and filtering
- Core protocol of internet connectivity
- Scales across large administrative domains
- Focuses on reachability and policy rather than only shortest path
Definition
BGP is a path-vector routing protocol used to exchange reachability information between autonomous systems. It is the main protocol for inter-domain routing on large networks.
Concept
BGP is a core networking protocol used for routing between separate autonomous systems. It supports policy-based inter-domain route exchange at internet scale by advertising prefixes along with policy and path attributes, allowing networks to choose which routes to accept, prefer, or propagate. BGP trades global reachability and flexible interconnection against control complexity and configuration risk. It exists throughout the internet, in service provider networks, at enterprise edges, and in cloud interconnects.
Explainer
BGP operates by enabling autonomous systems to advertise prefixes along with policy and path attributes. This allows networks to make informed routing decisions based on administrative policy rather than shortest path alone. Constraints include policy complexity, route filtering, convergence time, and trust boundaries between networks. Failure modes include route leaks, hijacks, incorrect policy configuration, unstable convergence, and asymmetric or unintended traffic paths. BGP is fundamental to large-scale inter-network connectivity and enables the interconnected nature of modern internet infrastructure, service provider networks, and cloud ecosystems. Cross-industry relevance is strong wherever autonomous systems must exchange routing information reliably and with policy control.