Autonomous System

Based on RFC 4271, the Autonomous System (AS) refers to a set of routers under a single technical administration. ASes use an interior gateway protocol (IGP) and common metrics to determine how to route packets within the AS, and an inter-AS routing protocol to determine how to route packets to other ASes. Since the introduction of this definition, several IGPs are commonly used for a single AS and several sets of metrics within an AS are sometimes used. The administration of an AS to other ASes still emerges with a single coherent interior routing plan and a consistent picture of the destinations that are reachable through it even when multiple IGPs and metrics are utilized.

Request For Comments. Archival series dedicated to documenting Internet technical specifications, including general contributions from the Internet research and engineering community as well as standards documents (RFC Editor Model, Version 3).