一种IP数据包快速分类算法

为了提高查找效率,在无冲突哈希查找算法和Grid of Tries算法的基础上提出了一种基于无冲突哈希和多比特Trie树(NHMT)的IP分类算法.该算法的核心有3部分:哈希函数的构造,主要是采用基于目的端口和协议两域构造哈希函数,使得在最坏情况下完全避免了空间爆炸问题;在Grid of Tries算法的基础上,对Grid of Tries算法改造成修剪的Trie树和多比特Trie树,以减少空间复杂度;在无冲突哈希查找算法的基础上扩展一层用于存放源端口号(或范围),扩展后一般要提高算法的时间复杂度,要通过引入多比特Trie树的方法进行解决.对于空间复杂度方面与无冲突哈希查找算法比较,一般情况下不增加空间复杂度.通过仿真,当对10 000条规则进行包分类时,该算法的分类速度可以达到1 Mbit/s,所消耗的最大内存为8.2 MB.

IP packet fast classification algorithm

In order to improve lookup efficiency,a novel IP classification,NHMT(non-collision Hash and nultibit-trie tree) is proposed, which is based on non-collision Hash trie-tree algorithm and grid of tries algorithm.The core of this algorithm has three parts: constructing Hash function mainly based on destination port and protocol type field so that the hash function can avoid space explosion problem;transforming Grid of tries for the trie-tree pruned and multibit-trie tree in order to reduce space complexity;adding a floor based on non-collision hash algorithm as source port number(or scope).After expanding normally,this doesn't increase the time complex degree of algorithm because the multibit trie tree is introduced.Space complexity consumed and space requirement are less than those of non-collision hash algorithm.Test results show that the classification rate of NHMT algorithm is up to 1 Mbit/s and the maximum memory consumed is 8.2 MB for 10 000 rules.