The Office of Naval Research (ONR) SISTO program is a two-year project which purpose is to advance the state of the art of content discovery and distribution technology, so that mission traffic requirements are satisfied in tactical environments. SISTO focuses on the operation of torrent protocols in tactical edge environments, where it is envisaged to operate among small to medium-sized peer groups in discontinuous, intermittent, low-bandwidth (DIL) network --consistent with the standards and service-oriented technologies planned for enterprise networks.
Within tactical edge environments, it is difficult to locate and share large distributed content. The BitTorrent protocol has solved this problem on scale-free networks through useful features such as object fragmentation, which allows peers to distribute and/or share portions/fragments of data objects prior to the whole object being acquired. The BitTorrent protocol also aids in group oriented dissemination, where object fragments may be acquired from different peers in the group at different times. These features enable a high degree of disruption tolerance and opportunistic use of transient bandwidth. However, issues arise when the BitTorrent protocol is run over a DIL network where connectivity and bandwidth are constantly in flux.
SISTO uses the BitTorrent technology as a baseline. The SISTO solution has three key components:
- torrSISTO: a novel, torrent-style, fault-tolerant, and opportunistic bandwidth-exploiting dissemination protocol for DIL networks
- disSISTO: a robust, distributed, service discovery overlay architecture
- gateSISTO: efficient interoperation with enterprise services using discovery aggregation and proactive, discovery driven caching
- A highly efficient methodology, designed for mobile DIL and serverless networks, for pulling content by adding proactive seeding, and network and path awareness.
- The use of a highly survivable and lightweight service mechanism for torrent discovery and announcement, instead of using native BitTorrent procedures.
- A distributed serverless tracker mechanism based on metrics appropriate for DIL networks.
- Dynamic control of key torrent parameters and actions based on torrents, peers, network state and policy.
- A design that can function with both unicast and multicast routing protocols, and will take additional advantage of multicast routing when it is available.