With the transformation of the Internet into a commercial infrastructure, the ability to provide customer-specific and differentiated services has become as important as the ability to meet the massive increases in bandwidth demand. Internet service providers would also like to provide Internet protocol (IP)-based virtual private network (VPN) services that satisfy customer-specific service level agreements using the same shared infrastructure. To meet these demands, it is necessary that routers and switches, in addition to being fast enough to meet ever increasing bandwidth demands, also be capable of providing quality of service (QoS) in a customer-specific manner. This paper describes the architecture, features, and technology innovations of Lucent Technologies' PacketStar 6400-Series IP switch - the first IP switch designed specifically to meet the rising bandwidth demand and the rising need for differentiated services of the evolving, multiservice QoS-capable Internet.