A Time-Scale Decomposition Approach to Measurement-Based Admission Control.pdf

A Time-Scale Decomposition Approach toMeasurement-Based Admission ControlMatthias Grossglauser David N. C. TseDept. of Electrical Engineering and Computer SciencesUniversity of CaliforniaBerkeley, CA 94720, USAfgrossgla,dtseg@eecs.berkeley.eduAbstractWe propose a time-scale decomposition approach to measurement-based admission con-trol (MBAC). We identify a critical time-scalefTh such that: 1) aggregate trac uctuationslower than fTh can be tracked by the admission controller and compensated for by owadmissions and departures; 2) uctuations faster than fTh have to be absorbed by reservingspare bandwidth on the link. The critical time-scale is shown to scale as Th=pn, where This the average ow duration and n is the size of the link in terms of number of ows it cancarry. A MBAC design is presented which lters aggregate measurements into low andhigh frequency components separated at the cuto frequency 1=fTh, using the low frequencycomponent to track slow time-scale trac uctuations and the high frequency componentto estimate the spare bandwidth needed. Our analysis shows that the scheme achieveshigh utilization and is robust to trac heterogeneity, multiple time-scale uctuations andmeasurement errors. The scheme uses only measurements of aggregate bandwidth anddoes not need to keep track of per- ow information.1 IntroductionIn order to make quality of service (QoS) guarantees, a network must exercise ow admissioncontrol. Admission decisions are based on some trac characterization, such as eectivebandwidths [11, 5] or leaky bucket descriptors [14]. The traditional approach to admissioncontrol assumes that a trac descriptor is provided by the user or application for each owprior its establishment [15]. However, this approach suers from several problems. Chiefamong them is the inability of the user or application to come up with tight trac descriptorsbefore establishing the ow. This is especially so when the bandwidth uctuates over multipletime-scales. A