改进的TCAM路由更新方法与实现

An Improved Method and Implementation for TCAM Route Updating

基于TCAM的硬件路由查找算法能够在一个时钟周期内完成最长前缀匹配,实现快速路由查找和分组转发。但路由表表项的有序性使得更新过程比较复杂从而成为TCAM路由技术发展的瓶颈。根据不同长度前缀表项的分布特性及路由表稳态时的更新规律,优化了路由表的空间分配,并引入了缓冲池的思想,提出了一种改进的路由表更新方法,从而提高路由表更新效率。

Routing lookup algorithms based on TCAM can complete a longest prefix matching （LPM） in one cycle and implement high-speed packet routing and forwarding .But as the route table has to keep the sequence of all entries, the updating process is rather complicated and has become the bottleneck of TCAM routing techniques. Research was made on the distributing features of different-length prefixes and the updating character of route table in stable state, and the allocation of route space was optimized accordingly. Furthermore, an improved algorithm for route updating was proposed based on buffer pool（BP） to improve the updating efficiency.