A scheme for guaranteeing delays in packet-switched WANıs is proposed, based on the assumption that reasonable worst-case performance bounds for intermediate swtiches can be obtained. The scheme is based on deadline scheduling and distinguishes deterministic from statistical real-time channels; the latter are "probabilistically real-time" while the former offer hard guarantees even in continued bursty conditions. Mathematically rigorous tests are used to determine whether the criteria for each channel type can be met at an intermediate switch already serving a finite number of channels. An additional delay-bounds test, also mathematically rigorous, is used to avoid scheduler saturation, in which the approaching deadlines for a set of packets overlap so much that scheduler CPU cycles become the bottleneck to satisfying the scheduling constraints.
Simulation is used to derive preliminary results. As expected, the scheme gives the best load balancing and network utilization with bursty traffic (especially for statistical channels).