BGP is a path vector protocol. This differs from distance vector (RIP) and link-state (OSPF) protocols.
Path vector characteristics:
- Routes include the complete AS path to the destination
- No hop count or metric is exchanged (policies decide)
- The path itself prevents loops
Example route announcement: Prefix: AS_PATH:
This says: "To reach , go through AS , then AS , then arrive at AS ." If your ASN appeared in this path, you'd reject it (loop detected).