Virtual time reference system: a unifying scheduling framework forscalable support of guaranteed services

摘要

We propose and develop a novel virtual time reference system as anunifying scheduling framework to provide scalable support for guaranteednservices. This virtual time reference system is designed as a conceptualnframework upon which guaranteed services can be implemented in anscalable manner using the DiffServ paradigm. The key construct in thenproposed virtual time reference system is the notion of packet virtualntime stamps, whose computation is core stateless, i.e., no per-flownstates are required for its computation. We lay the theoreticalnfoundation for the definition and construction of packet virtual timenstamps. We describe how per-hop behavior of a core router (or rather itsnscheduling mechanism) can be characterized via packet virtual timenstamps, and based on this characterization establish end-to-end per-flowndelay bounds. Consequently, we demonstrate that, in terms of its abilitynto support guaranteed services, the proposed virtual time referencensystem has the same expressive power and generality as the IntServnmodel. Furthermore, we show that the notion of packet virtual timenstamps leads to the design of new core stateless scheduling algorithms,nespecially work-conserving ones. In addition, our framework does notnexclude the use of existing scheduling algorithms such as stateful fairnqueuing algorithms to support guaranteed services