摘要：Active and programmable networks change the functionality of routers and switches by using VPN endpoints and active packets. The authors present a new packet scheduling scheme called active scheduling to control and maintain QoS parameters in virtual private networks (VPNs) within the confines of adaptive and programmable networks. In active scheduling a VPN endpoint on the router monitors the accumulated queuing delay for each service. To control and to keep the end-to-end delay within the bounds, the delays of the packet transmitted are adjusted dynamically by VPN endpoints on the routers spanning the VPN. If there is an increase or decrease in delay of packets, VPN endpoints on a source node informs the destination node to adjust the delay of the packets. This keeps the end-to-end delay of services within the specified bounds and offers better QoS compared with VPNs using static priority scheduling. An algorithm for active scheduling is described and simulation results are presented and compared with priority scheduling.
