A Methodology for Deriving Per-Flow End-to-End Delay Bounds in Sink-Tree DiffServ Domains with FIFO Multiplexing

In a DiffServ architecture, packets with the same marking are treated as an aggregate at core routers, independently of the flow they belong to. Nevertheless, for the purpose of QoS provisioning, derivation of upper bounds on the delay of individual flows is required. In this paper, we consider the derivation of per-flow end-to-end delay bounds in DiffServ domains where peregress (or sink-tree) FIFO aggregation is in place. We expose a general methodology to derive delay bounds, and we instantiate it on a case study. We show that the methodology yields a tighter bound than those available from the literature, and we express a worst-case scenario for the case study network, in which the bound is actually achieved.