Improving routing in the global Internet

Abstract: Routing is an important part of the Internet and even though routing in the Internet has been investigated since Internet's creation, there are still open issues. Routing protocols have been evolved since the birth of Internet. Currently the Border Gateway Protocol(BGP) is the de-facto standard inter domain routing protocol on the Internet. In 1990 came the first version of BGP which has evolved to todays BGP-4 through several versions and extensions. The capability has increased for every new version and extension, but so has the complexity. This makes it harder to get an overview of how routers behave. In many cases the global view of the routing within the Autonomous System (AS) is missing. When the global view is missing, it is difficult for routers to chose a stable route and in some cases it is impossible. Oscillation is one of the larger problems and for I-BGP several solutions have been suggested. We present a new algorithm that prevents intra AS oscillation. The basic idea is to store routes that arenot explicitly removed because those routes can still be used, although they are currently not active. This way the selection algorithm has a larger set of routes to choose from when it selects the best route. Routes that are not currently used can not be selected but can be used to remove others from the allowed set. BGP can also be improved by adjusting it to a new decentralized router architecture and at the same time solving several intra AS problems. We have been investigating this problem and suggested a modularization of BGP. The modularization is designed to fit on top of the Forward Element and Control Element separation of the router. The forwarding table and session manager have been separated from the decision process and Routing Information Bases(RIB). The solution is very flexible and allows that the router is built with redundancy and still keeps the cost down. We also present algorithms for calculating the k shortest paths in a distributed manner. This algorithm has its roots in BGP. It runs in waves to compute the k shortest paths. The algorithm produces paths that can be used for routing to solve load-balancing problems or as backup paths.