A fast table update scheme for high-performance IP forwarding

The construction of routing tables has been studied extensively. Although existing work has certain advantages, it either uses complicated data structures which result in large storage requirements and high complexity for updating/building the forwarding table, or it is not scalable to fit in IPv6. Lampson et al. (1999) proposed an IP lookup algorithm which performs binary search on prefixes (BSP). The algorithm is attractive, even for IPv6, because of its bounded worst-case memory requirement. For achieving fast forwarding, the cost is the slowing down of insertion. Although this can be justified, the performance of routing-table reconstruction in BGP is too time-consuming to handle frequent route updates. We propose a fast forwarding table construction algorithm, which can handle more than 4,000 route updates per second. Moreover, it is simple enough to fulfil the need of fast packet forwarding. By using the modified multiway search tree, we can further reduce the depth of the tree and eliminate storage for pointers. This reduces the forwarding table size and shortens the lookup time.