AC algorithms in AQUILA QoS IP network

This paper presents the admission control (AC) algorithms that are implemented in the prototype multiservice AQUILA QoS IP network [4]. The discussed algorithms were developed for regulating traffic submitted to network services (NS) dedicated for handling: (1) real-time streaming traffic of variable bit rate (VBR) type, and (2) elastic traffic, produced by greedy TCP sources. For the former NS, named Premium VBR, the measurement based AC (MBAC) scheme is proposed. The applied approach employs the well known Hoeffding bound formula [2] for calculating required link capacity to assure packet loss ratio at a predefined level. Moreover, this method is supported by the declarations about the peak bit rate as well as by the measurements of mean bit rate on aggregate flow level. For the latter NS, named Premium Multimedia, two alternative AC algorithms are investigated, both designed for assuring requested TCP throughput. While the first of them follows the Token Bucket Marking (TBM) concept [12], the second one adjusts the advertised TCP window size to enable an ideal TCP behaviour (i.e. lossless packet transfer). The simulation results are included for illustrating the advantages of the discussed algorithms.