Defining defects, errors, and service degradations
ACM SIGSOFT Software Engineering Notes
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Many network applications that require quality-of-service (QoS) support, such as transmission of digital voice and video, tolerate a certain level of service degradation. In this study, a novel network service, referred to as service with bounded degradation (BD service), is presented that can take advantage of the delay tolerance of applications. Different from previous proposals for similar services, the BD service can guarantee hard lower bounds of the service degradation. This is achieved by strictly limiting the amount of traffic that is subject to service degradation. To implement a BD service, network traffic is partitioned into components with different delay requirements. Policing of the traffic components is achieved by multi-level leaky buckets. A novel scheduler, referred to as EDD-BD (earliest deadline due-bounded degradation) scheduler, performs switching of packets. Properties of the EDD-BD scheduler are presented and analyzed.