| 摘要 |
A high speed router employs a hashed radix tree method for IP route look-up operations. The first k bits of an X bit IP address are hashed and used as an index to a RAM whose output is a pointer to the root node of one of a plurality of radix trees. Taking into account the subnet mask of the IP address, each of the radix trees examines the significant bits of the remaining X-k bits of the IP address for a match. Each match is stored in memory at least until a better match is found. If a best match is found a pointer to a second RAM is emitted, whose output is the best route. The tree can be constructed such that one or more bits can be examined simultaneously at each level. To gain the benefit of examining multiple bits at each level and minimize the required memory, a perfect hashing method is employed to eliminate unnecessary nodes in each tree.
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