Emerging applications such as industrial automation, in-vehicle, professional audiovideo,\nand wide area electrical utility networks require strict bounds on the end-to-end network\ndelay. Solutions so far to such a requirement are either impractical or ineffective. Flow based\nschedulers suggested in a traditional integrated services (IntServ) framework are O(N) or O(log N),\nwhere N is the number of flows in the scheduler, which can grow to tens of thousands in a core\nrouter. Due to such complexity, class-based schedulers are adopted in real deployments. The classbased\nsystems, however, cannot provide bounded delays in networks with cycle, since the\nmaximum burst grows infinitely along the cycled path. Attaching a regulator in front of a scheduler\nto limit the maximum burst is considered as a viable solution. International standards, such as IEEE\n802.1 time sensitive network (TSN) and IETF deterministic network (DetNet) are adopting this\napproach as a standard. The regulator in TSN and DetNet, however, requires flow state information,\ntherefore contradicts to the simple class-based schedulers. This paper suggests non-work\nconserving fair schedulers, called â??regulating schedulersâ?? (RSC), which function as a regulator and\na scheduler at the same time. A deficit round-robin (DRR) based RSC, called nw-DRR, is devised\nand proved to be both a fair scheduler and a regulator. Despite the lower complexity, the input portbased\nnw-DRR is shown to perform better than the current TSN approach, and to bind the end-toend\ndelay within a few milliseconds in realistic network scenarios.
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