1. A network device for use in a Fibre Channel network, the network device comprising: one or more Fibre Channel ports; and a zoning engine for implementing zoning in the Fibre Channel network, the zoning engine comprising: (a) a content addressable memory configured or designed to store information identifying distinct destinations on said Fibre Channel network and locations in a membership table for zoning decision vectors for the distinct destinations; (b) a membership table designed or configured to store the zoning decision vectors for the distinct destinations identified in the content addressable memory, wherein each zoning decision vector is associated with a single destination and multiple available sources for said single destination on the Fibre Channel network and comprises a separate zoning rule for each combination of source and destination from among said single destination and the multiple sources; and (c) logic for (i) selecting a zoning decision vector from the membership table using information obtained from the content addressable memory based on destination information from an incoming frame, and (ii) selecting a zoning rule from the selected zoning decision vector using source information from said incoming frame, wherein selecting the zoning decision vector occurs separately from selecting the zoning rule and wherein the zoning rules in the zoning decision vector indicate whether the frame should be permitted or denied transmission to its destination.