Abstract: A look-up table for use in a bridge employing negative filtering for interconnecting first and second networks in a data communications system. Associated with each data transmission is a source and destination address each having a total of (m+n) binary data bits, the bridge passing the data transmission from one network to the other unless the destination address is found in the look-up table and corresponds to the sending network. The look-up table comprises an encoding means responsive to an (m+n) bit address for producing first and second codes having respectively m and n bits of data which together allow the (m+n) bit address to be decoded unambiguously, a random access memory (RAM) coupled to the encoding means and having m addressable locations each for storing at least n bits of data, and a contents addressable memory (CAM) coupled to the encoding means and having a plurality of addressable locations each for storing at least (m+n) bits of data.