• Implementing Real-time Provisioning for Space Link Extension (SLE) Service Instances

      Lokshin, Kirill; Puri, Amit; Irvin, Dana; Ross, Frank; Rush, Rebecca; Ingenicomm, Inc. (International Foundation for Telemetering, 2012-10)
      Space Link Extension (SLE) is a set of recommended standards for mission cross support developed by the Consultative Committee for Space Data Systems (CCSDS). The SLE recommendations define protocols for extending the space link from ground terminals to other facilities deeper within a ground network, allowing distributed access to space link telecommand and telemetry services. The SLE protocols are widely used to provide cross support between sites, programs, and agencies. In traditional SLE deployments, individual service instances have been manually provisioned well in advance of the commencement of cross support for a particular mission, and hardware and software resources have been allocated to those service instances at the time of provisioning. While valid, this approach requires that dedicated resources be provided for each mission and service instance, and limits an SLE provider's ability to reallocate resources in real time based on system availability or other factors. This paper discusses an alternative approach to SLE service provisioning, in which individual service instances are assigned resources from a common resource pool at the time that each service instance is initialized. The paper addresses the key design elements and technical tradeoffs involved in this approach, and discusses the potential benefits with regard to load balancing, equipment reuse, and resiliency against system failure.
    • Implementing Space Link Extension (SLE) for Very High Rate Space Links

      Lokshin, Kirill; Puri, Amit; Irvin, Dana; Ross, Frank; Rush, Rebecca; Ingenicomm, Inc. (International Foundation for Telemetering, 2012-10)
      Space Link Extension (SLE) is a set of recommended standards for mission cross support developed by the Consultative Committee for Space Data Systems (CCSDS). The SLE recommendations define protocols for extending the space link from ground terminals to other facilities deeper within a ground network, allowing distributed access to space link telecommand and telemetry services. The SLE protocols are widely used to provide cross support between sites, programs, and agencies. Traditional SLE protocol implementations have been limited in their ability to support high data rates and large numbers of concurrent service instances. Such limited solutions were sufficient to support the needs of spacecraft health and status or older, low-rate science data. More recent missions, however, have required significantly increased data rates on both uplink and downlink paths, necessitating a new approach to SLE implementation. This paper discusses the design principles involved in implementing the SLE protocols in support of high channel and aggregate mission data rates, with particular focus on the tradeoffs necessary to provide SLE link capability at sustained single-channel rates above 1 Gigabit per second. The paper addresses significant performance bottlenecks in the conventional SLE protocol stack and proposes potential mitigation strategies for them.