A fast two-way IP lookup algorithm based multibit-trie

Due to the rapid growth of traffic in the Internet, backbone links of several gigabits per second are commonly deployed, which means backbone routers must be able to forward millions of packets per second. One of the most important steps of routing is lookup in the routing table, which is also the bottleneck in high-speed routing process. Some traditional IP lookup algorithms are focused at memory consumption, searching speed or update complexity respectively, with which we design an evaluation function to make this tradeoff. This evaluation function provides a new method to measure the integrated performance of routing lookup algorithm. Finally we provide a fast two-way IP lookup algorithm based multibit-trie, which makes one single lookup to the IP address to be processed in parallelism. In this article, we have analyzed the algorithm complexity in two aspects: memory using and lookup speed. Furthermore, we compare the performance of our two-way IP lookup algorithm with some former classic algorithms. The analytical result indicates the two-way algorithm has more superiority than other software lookup algorithms in integrated performance.