A communication device which includes a hardware trie search facility. At least part of a memory is divided into memory blocks, each of said blocks consisting of a multiplicity of locations, at least some of said locations each providing when accessed a pointer to another block and an indication of the size of the block. A shift register holds an address key, and a trie block is accessed using an address composed of a number of bits related to said indication of the size of the block. The key is shifted by said number of bits prior to a subsequent stage of the search. Part of the memory comprises an associated data table which includes entries of data enabling a packet to be forwarded and at least some locations in said blocks provide when accessed a pointer to an entry in the associated data table.