Agent system for inter-AS routing error diagnosis

The basic unit of Internet routing is called an autonomous system, or AS, defined as a set of routers under a single technical administration. The Internet currently comprises more than 12,000 AS's. Some are university or corporate networks; others are ISP networks. Inside an AS, a single authority controls the deployment of policies and protocols by which routers compute intra-AS paths, including paths to gateway or border routers. For inter-AS routing, the situation is more complicated. Most AS's manage the exchange of routing information through the Internet Engineering Task Force's border gateway protocol. BGP lets an AS advertise "reachability" information throughout the Internet by sending update information when network topology or routing policies change. BGP is a hop-by-hop protocol, which sends the information only to a gateway router's immediate neighbors. At NTT Network Innovation Laboratories, we have developed and are currently testing a multiagent-based system called Encore to automatically diagnose inter-AS routing problems. We briefly describe the problem addressed by the system, its design and current implementation, and recent test results.