A packet processor provides for rule matching of packets in a network architecture. The packet processor includes a lookup cluster complex having a number of lookup engines and respective on-chip memory units. The on-chip memory stores rules for matching against packet data. Each of the lookup engines receives a key request associated with a packet and determines a subset of the rules to match against the packet data. Based on a prefetch status, a selection of the subset of rules are retrieved for rule matching. As a result of the rule matching, the lookup engine returns a response message indicating whether a match is found.