What type of routing does BGP use?

BGP, or Border Gateway Protocol, uses a path-vector routing mechanism. This method is distinct from both distance-vector and link-state protocols, which represent two other primary types of routing algorithms.

Path-vector routing operates by maintaining the path information that gets updated as routing information is exchanged between BGP peers. Each BGP route advertisement includes not just the destination network information but also the complete path of Autonomous Systems (AS) that the advertisement has traversed. This characteristic allows BGP to employ policies for routing decisions based on the AS path and apply filtering based on specific routing preferences.

The path-vector approach is particularly advantageous for inter-domain routing, as it enables BGP to effectively prevent routing loops and ensure better control over routing decisions within different autonomous systems. This capability makes BGP suitable for use in the internet's core, where multiple administrative domains need to connect.

The other types of routing mentioned—distance-vector and link-state—serve their own purposes in different contexts, often within internal networks rather than at the inter-domain level where BGP shines. Understanding BGP's reliance on a path-vector mechanism highlights its role and function within complex routing scenarios.