A network device is provided. The network device includes: a hash memory and a controller. The hash memory has a plurality of hash tables, wherein each hash table includes a plurality of entries, and each entry in each hash table has a signature field, and a key field. The controller is configured to map a search key to a plurality of entries of the hash tables and perform longest prefix matching (LPM) on the search key based on the signature field and the key field of each mapped entry in the mapped hash tables.