Impact of satellite delay on protocol performance for ATM traffic over non-processing satellites

The proliferation of ATM applications over satellite depends on finding solutions to key issues such as appropriate operating system support, efficient networking protocol implementations, and state-of-the-art onboard processing and switching capabilities of the telecommunication satellites. Global grid architectures based on ATM technology satellite and terrestrial circuits are emerging rapidly. For satellite communications to play an important role in provisioning the ATM based services and networks, it is essential to demonstrate satellite configurations (for example, networking protocols, deep buffers) that are reliable and yield high throughput. Most of the research on ATM architectures is presently focused on using fiber optic (low bit error rate) transmission lines. However, mere substitution of research findings on ATM terrestrial circuit technology to satellite technology will not suffice to improve ATM performance. The communication frameworks over ATM satellite require some modifications to ATM equipment (buffering requirements), operating systems software, and communications protocols. Existing transmission protocols such as TCP/IP, XTP, AALs, TP-4, etc., which are suitable for use in the terrestrial networks, will require some modifications (response timers, frame sizes, etc.). We examine ATM performance issues such as overall throughput, bearer quality of services parameters (congestion control and cell delay), and transmission protocols. We also provide examples of ATM tests performed during October '93 by NCCOSC RDT&E Division (NRaD) San Diego and GTE Government Systems under a Cooperative Research and Development Agreement (CRADA) using GTE SPANet ATM switches.<
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