Measurement Analysis of Cell Stream in ATM Network Integrating CATV and Internet

The project of interconnecting CATV in Hyogo Prefecture, Japan has started since March, 1998. In this project, there are three CATV companies in Hanshin area; Kobe, Nishinomiya and Amagasaki. An ATM switch is equipped in each company and these CATVs are connected serially in the above order. Each company provides the video service to the rest of companies using the MPEG2 over ATM. In the service area of each CATV, subscribers are able to access the Internet using cable modem. In our testbed network, cells with two types of requirement for QoS are multiplexed; cells for MPEG2 which require the real-time transmission and those for Internet packets which are much more sensitive for the cell loss ratio. Recently, it has been shown that the tra c such as Ethernet LAN, WAN, and ATM network has the statistical characteristics of self-similarity and long-range dependency (LRD). In general, the tra c with LRD degrades the network performance and hence it is important to capture the tra c characteristics in terms of LRD for investigating the performance measures such as cell loss probability, transmission delay, and jitter process. In this paper, we investigate the characteristics of cell stream from the point of view of self-similarity and estimate the Hurst parameters under the various situations on our experimental network. Our results show that if there exists self-similarity in the ATM network integrating CATV and Internet, cells for Internet play a crucial role for the self-similar nature of the network.