© 2005 Springer Science+Business Media, Inc. Better Alternatives to OSPF Routing1

Abstract. The current standard for intra-domain network routing, Open Shortest Path First (OSPF), suffers from a number of problems—the tunable parameters (the weights) are hard to optimize, the chosen paths are not robust under changes in traffic or network state, and some network links are over-used at the expense of others. We present prototypical scenarios that illustrate these problems. Then we propose several variants of a protocol to eliminate or alleviate them and demonstrate the improvements in performance under those scenarios. We also prove that these protocols never perform significantly worse than OSPF and show that for at least a limited class of network topologies, it is possible to find efficiently the optimal weight settings. Some of the problems with OSPF are well known; indeed, there are several routing protocols that perform better than OSPF in routing quality (i.e., in terms of congestion, delay, etc.). OSPF’s popularity persists in part because of its efficiency with respect to several resource bounds. In contrast, many competing protocols that provide routing superior to OSPF are computationally prohibitive. Motivated by this consideration, we designed our protocols not only to achieve better routing quality than OSPF, but also to use resources in amount comparable with OSPF with respect to offline broadcast communication, size of and time to compute routing tables, packet delivery latency, and packet header structure and size