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The cornerstone of the U.S. Navy's implementation of network centric warfare is the Information Technology for the 21st Century (IT-21) Intranet. The IT-21 Intranet relies on Asynchronous Transfer Mode (ATM) backbones for data transfer. An essential service provided by the IT-21 Intranet is video teleconferencing (VTC). However, the current ATM standard does not support the multipoint-to-multipoint multicast requirements for robust VTC applications. This work builds upon the SMART algorithm, an existing protocol that provides support for ATM multipoint-to-multipoint multicast over a single virtual channel (VCC), and modifies it to ensure that each source has fair access to the VCC. Fair access is ensured to multiple sources through the use of a metric that takes into account the relative magnitude of each source's queue size and cell age. The improved SMART algorithm is modeled using the MIL3's Optimized Network Engineering Tool (OPNET). Fair access to each source is shown using both audio and video source models. VCC utilization is examined and shown to improve for the video case as the number of sources increase. The increased overhead due to the use of Resource Management (RM) cells is also examined. |
