Patent ID: 7043600

Claim:
A CAM system for generating an output on a bus in response to a key, the CAM system comprising: at least two clusters that each include M CAM devices, wherein each CAM device has a priority N within the cluster to which it belongs, where N ranges from 1 to M, and each CAM device includes: i) a CAM array configured to hold entries and to determine if each entry matches the key; ii) (M−1) disable connections, where the CAM device of priority N has (N−1) of the disable connections programmed as inputs configured to receive disable-in signals from the (N−1) higher-priority CAM devices within the cluster, and has the remaining (M−N) disable connections programmed as outputs configured to provide a disable-out signal to the (M−N) lower-priority CAM devices within the cluster; and iii) a cascade circuit configured to disable the CAM device from driving the output onto the bus when any of the disable-in signals received by the CAM device are asserted; and a controller configured to receive a cluster-match signal from the clusters and to generate a cluster-disable signal for the clusters, wherein the cluster-disable signal for a particular cluster is asserted when any cluster-match signal received by the controller from any cluster having higher priority than that particular cluster is asserted; wherein each CAM device further includes a connection configured to receive the cluster-disable signal for the cluster containing the CAM device and a connection configured to provide the cluster-match signal for that cluster; and wherein each cascade circuit is further configured to disable the CAM device from driving the output onto the bus when the cluster-disable signal is asserted.