PERFORMANCE ANALYSIS OF SDN-SPECIFIC ERROR RECOVERY PROCEDURES

This paper evaluates and compares the performance of two error recover y schemes being applied to the European Space Data Network (SDN). The SDN comprises several heterogeneous subnetwork technologies providing end-to-end connectivity between ground and spacecraft application proc esses. Previous work(1-3) considers the interconnection protocol archi tecture, for which two approaches have been proposed; these are distin guished by the type of network service used to perform subnetwork inte rconnection: connection-oriented and connectionless. In the former app roach, error recovery from message loss or corruption is performed by each individual subnetwork along the path (step-by-step); in the latte r approach, error recovery is provided on an end-to-end basis. To comp are performance characteristics of the two architectures, two models a re analysed, taking into account the effects of physical link errors, propagation delays of messages and their acknowledgements, finite buff er capacities on gateways, buffering of unacknowledged messages, timeo ut mechanisms, computation time on gateways and end systems, and fragm entation and reassembly. Numerical results show that, for the SDN envi ronment considered, the step-by-step approach is superior to the end-t o-end approach. The techniques applied are standard ones, considering a very complex scenario of different network characteristics.