以太无源光网的 DBA 算法应当高效、公平,并保证服务质量.分析了影响链路利用率的各种因素,提出避免 DBA 延时、消除时隙末损耗等 4 项提高链路利用率的原则.同时给出了针对性措施,比如分组交织,基于帧边界授权.遵循这些原则,链路效率能够超过96%.按照SLA带宽比例,面向用户授权带宽能够实现用户间公平.为保证服务质量,应当采取区分服务模型,实行闸门式优先级队列调度方式,选取适当长度的轮询周期.%In Ethernet passive optical networks, a good dynamic bandwidth allocation (DBA) scheme is expected to support quality-of-service and be efficient and fair. All factors concerning link utilization are studied, thus four principles are proposed to boost link utilization. Practical methods complying with these principles are also presented, such as interleaved transmission, granting based on threshold-reporting. DBA realizing these principles can achieve optimal link utilization higher than 96%. It is suggested that DBA should achieve inter-user fairness. A feasible way to guarantee both inter-user fainless and inter-class fairness is to hierarchically grant bandwidth to each subscriber in proportion to his agreement bandwidth. Adopting DiffServ model, gated priority scheduling and properly selected cycle length, quality-of-service can be satisfied.
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