Abstract: An input lookup key is hashed and the hashed key divided into stride bits into a multi-level Trie structure. A compression function logically combines the stride bits to generate the compressed index bits into the stride tables. The bucket in the last stride table found by the hashed key may have several keys that collide at the same hash value. Discriminant bits are read from the key and select a stored key in the bucket table for verification of its result. Since the hashed key is a compression of the longer input key, more information is contained per bit of the hashed key than in the long key. The multi-stride lookup is performed first on the hashed key, allowing a faster convergence to the lookup result. The first stride can index a single hash table, with the remaining hash bits and discriminant bits used to select from among colliding keys.

Abstract: A lookup is performed using multiple levels of compressed stride tables in a multi-bit Trie structure. An input lookup key is divided into several strides including a current stride of S bits. A valid entry in a current stride table is located by compressing the S bits to form a compressed index of D bits into the current stride table. A compression function logically combines the S bits to generate the D compressed index bits. An entry in a prior-level table points to the current stride table and has a field indicating which compression function and mask to use. Compression functions can include XOR, shifts, rotates, and multi-bit averaging. Rather than store all 2S entries, the current stride table is compressed to store only 2D entries. Ideally, the number of valid entries in the current stride table is between 2D-1 and 2D for maximum compression. Storage requirements are reduced.

Abstract: A lookup is performed using multiple levels of compressed stride tables in a multi-bit Trie structure. An input lookup key is divided into several strides including a current stride of S bits. A valid entry in a current stride table is located by compressing the S bits to form a compressed index of D bits into the current stride table. A compression function logically combines the S bits to generate the D compressed index bits. An entry in a prior-level table points to the current stride table and has a field indicating which compression function and mask to use. Compression functions can include XOR, shifts, rotates, and multi-bit averaging. Rather than store all 2S entries, the current stride table is compressed to store only 2D entries. Ideally, the number of valid entries in the current stride table is between 2D?1 and 2D for maximum compression. Storage requirements are reduced.