This diploma thesis deals with packet classification in computer networks. The problem of packet classification is described, together with requirements for classification algorithm. Then, necessary theoretical background is introduced. Contemporary approaches to the classification are described, together with the critique of the current state of the field. The main focus of the work is the new algorithm of packet classification based on problem decomposition. Unique property of the algorithm is constant time complexity in terms of external memory accesses. Algorithm implemetation is proposed, using FPGA and one external memory. Planned prototype may achieve throughput of 64 Gbit/s in the worst case