IRED: a router algorithm for supporting integrated services in the Internet

A novel router flow control scheme, called IRED, is proposed for supporting both guaranteed bandwidth (GB) and best-effort (BE) flows in the Internet. In IRED, network resources are reserved for each GB flow using resource reservation protocol (RSVP). At each router, packet scheduling behavior is established to meet the QoS requirements of each GB flow. For supporting BE flows, a router senses incipient congestion by monitoring the average buffer occupancy of BE packets with respect to the total buffer space available for BE traffic. When a pre-defined occupancy threshold is exceeded, IRED randomly drops BE packets to notify the selected senders to slow down their transmission rates. Our extensive simulation results reveal that IRED can provide QoS guarantee on delay and packet dropping probability for GB flows, and can achieve excellent throughput performance for BE flows. We also find that IRED can protect BE flows from the harassment of unfriendly greedy GB flows as well as non-adaptive BE flows.