Pathvectorprotokolla

Pathvectorprotokolla is a class of inter-domain routing protocols that advertise routes together with a path vector, a sequence of domains through which the route has traversed. The primary goal is to enable scalable routing across many autonomous systems while supporting policy-based decisions and preventing routing loops.

In operation, a router advertising a route attaches a path vector that lists the domains or autonomous systems along the path. Each time a router forwards or imports a route, it appends its own identifier to the path and applies policy checks. A route is considered valid for further propagation only if the resulting path does not already contain the local domain, a mechanism that prevents loops and allows operators to enforce routing policies.

BGP is the best-known example of a pathvectorprotokolla in use on the Internet. It uses an AS_PATH attribute as the path vector, and supports external and internal sessions, route reflectors, and policy-based routing. Other designs may introduce additional attributes or different encoding, while preserving the core concept of path-based routing decisions.

Security and reliability considerations include exposure to misconfigurations and prefix hijacking; mitigation measures include authentication (MD5, TLS), route validation with RPKI, and proposed extensions such as BGPsec. Deployment concerns center on convergence speed, policy complexity, and the operational requirements for large-scale networks.