Guaranteed rate scheduling with adaptable excess bandwidth distribution

Although guaranteed rate (GR) schedulers such as WFQ (weighted fair queueing) can provide a hard delay bound for a leaky-bucket-conditioned traffic flow, the bandwidth requirement is high if the flow is bursty. On the other hand, the GR property is insensitive to how instantaneous excess bandwidth is distributed by a GR scheduler. Such excess bandwidth could be adaptively distributed to improve delay distribution tails. We present a sub-class of GR schedulers, called general dynamic guaranteed rate queueing (GDGRQ), for networks with fixed packet sizes. While keeping the GR property, GDGRQ schedulers can dynamically and arbitrarily distribute any excess bandwidth within short periods. GDGRQ is a framework for the design of schedulers that can both provide hard delay bounds and adaptively distribute excess bandwidth in order to control delay distribution tails and deliver statistical delay quality of service (QoS).