This book constitutes, together with its compagnion LNCS 2093,the refereed proceedings of the First International Conference of Networking, ICN 2001, held in Colmar, France, June 2001. The 168 papers presentedn were carefully reviewed and selected from around 300 submissions. The proceedings offers topical sections on third and fourth generation, Internet, traffic control, mobile and wireless IP, differentiated services, GPRS and cellular networks, WDM and optical networks, differentiated and integrated services, wirless ATM multicast, real-time traffic, wireless, routing, traffic modeling and simulation, user applications, mobility management, TCP analysis, QoS, ad hoc networks, security, MPLS, switches, COBRA, mobile agents, ATM networks, voice over IP, active networks, video communiccations, and modelization.