Abstract:

Concerning the low efficiency of present methods of IP lookup, a new data lookup algorithm based on Multi-Bit Priority Tries (MBPT) was proposed in this paper. By storing the prefixes with higher priority in dummy nodes of multi-bit tries in proper order and storing the prefixes for being extended in an auxiliary storage structure，this algorithm tried to make the structure find the longest matching prefix in the internal node instead of the leaf node. Meanwhile, the algorithm avoided the reconstruction of router-table when it needed to be updated. The simulation results show that the proposed algorithm can effectively minimize the number of memory accesses for dynamic router-table operations, including lookup, insertion and deletion, which significantly improves the speed of router-table lookup as well as update.

Key words: IP address lookup, multi-bit trie tree, longest matching prefix, Multi-Bit Priority Tries (MBPT) tree

摘要：

针对现有路由表查找方法效率低的问题，提出了一种基于多分支优先级树的数据查找算法。该算法将优先级较高的前缀依次存储在原多分支树的虚节点上，将需要进行扩展的前缀存储在辅助存储结构中，从而在路由查找时，该方法可在内部节点找到最长前缀匹配而无需查找到叶子节点，同时避免了在路由表更新时对路由表的重建。仿真结果表明，提出的查找算法能够有效减少在对路由表查找、插入和删除操作所需的内存访问次数，并大幅度地提高路由查找及其更新速率。

关键词: IP路由查找, 多分支tire树, 最长前缀匹配, 多分支优先级树