Thanks for the explanation. The literature I was refering to includes: . R. Jain, A Comparison of Hashing Schemes for Address Lookup in Computer Networks, IEEE Trans. on Communications, 1992, v40, n3. . Z. Cao, Z. Wang, E. Zegura, Performance of Hashing-based Schemes for Internet Load Balancing, IEEE INFOCOM 2000, p332-341. Weiguang