Computing Deterministic Delay Bounds
If flow is shaped by a token bucket (sigma, rho), all routers along the “h”-hop path employ WFQ schedulers, and the flow is assigned a rate of rho at each hop, then end-to-end delay of a packet is bounded by:
(sigma / rho) + (h * max_pkt_size / rho) +
total approximation error + total propagation delay
A flow is totally isolated, even if other traffic is not shaped at all
Cons: bandwidth and delay are coupled
WFQ does not bound jitter
A non-work-conserving scheduler (e.g., Stop-and-Go, jitter-EDD) may be used to bound jitter