| 摘要 |
A video on demand system includes one or more hybrid fiber coax access networks connecting set top units to corresponding head end units. The head end unit for an access network is connected to an asynchronous transfer mode wide area network (ATM WAN). A hierarchical system of video servers, including at least one center server and at least one local server, or cache node, are also connected to the ATM WAN. When a user wishes to select a video, a service control unit coupled to the ATM WAN generates a selection list of proposed videos for which server and network resources are available to immediately serve the user-selected video. The service control unit determines whether server and network resources are available by sending separate queries to server and network resources management control units. Alternatively, the service control unit may generate the selection list based on whether the probability of a particular video being immediately served is greater than a threshold.
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