Congestion avoiding mechanism based on inter-domain hierarchy

Abstract

Inter-domain routing is ensured by BGP. BGP messages carry no information concerning quality parameters of routes. Our goal is to provide domains with information regarding the congestion state of other domains without any changes in BGP. A domain, which is aware of congested domains, can choose a bypass instead of a route exhibiting possible QoS problems. We propose a distributed mechanism sending alert messages in order to notify domains about other domains congestion state. Our solution avoids flooding the Internet with signaling messages. It limits the number of alerts by taking advantage of the hierarchical structure of the Internet set by P2C and P2P relationships. Our algorithm is heuristic because it is a solution to an NP-complete and inapproximable problem. We prove these properties using the Steiner problem in directed acyclic graphs. The simulation runs show that our mechanism significantly diminishes the number of unavailable domains and routes compared to those obtained with "pure" BGP routing and with a theoretical centralised mechanism. © 2008 Springer-Verlag Berlin Heidelberg.