Conference 7.286::space

348.0. "Space Physics Analysis Network" by DICKNS::KLAES (Angels in the Architecture.) Fri Sep 25 1987 16:53

VNS TECHNOLOGY WATCH:                           [Mike Taylor, VNS Correspondent]
=====================                           [Nashua, NH, USA               ]

                             SPAN  
       
      Planning for SPAN (the Space Physics Analysis Network) began in
      1980, and operations commenced in 1981.  SPAN was originally
      oriented toward researchers in Solar Terrestial and Interplanetary
      Physics, but is now expanding to serve other disciplines.  SPAN is
      a multimission, correlative data comparison network serving
      projects and facilities of the American National Aeronautics and
      Space Administration (NASA) in collaboration with the European
      Space Agency (ESA). These agencies have traditionally set up data
      collection networks to serve specific space missions, but SPAN is
      mission independent, general purpose, low cost, and easy to
      connect to.  (However, it is sometimes used to support specific
      missions, such as the ICE mission to the Giacobibi-Ainner comet
      and the encounter with Comet Halley.)  It is an operational
      network in that it is not intended to promote the development of
      network technology, but it is a research network in that it
      provides an infrastructure for space-related research.  It was not
      created in order to access supercomputers, but supercomputers are
      becoming more available through it.

      Guidance for the networks is provided by the users through the
      Data System Users Workers Group (DSUWG) and project scientists. 
      Direct administration is done by project managers, network
      managers, and routing center managers. NASA pays for all the links
      while other participating organizations pay for their own host
      computers and network interfaces.  Much of the original hardware,
      such as the routing center computers, came from NASA.

      The upper layer protocols are DECNET.  The lower layers are
      provided by NASA's Program Support Communications Network (PSCN)
      and the NASA Packet-switch System (NPSS).  PSCN is a circuit
      switched network, that is, a collection of leased lines and
      microwave links.  NPSS consists of X.25 links, some of them over
      public X.25 networks.  The backbone of the network is four routing
      centers at the Goddard Space Flight Center in Greenbelt, Maryland,
      The Johnson Space Center in Houston Texas, the Jet Propulsion
      Laboratory in Pasadena, California, and the Marshall Space Flight
      Center in Huntsville, Alabama.  These are connected by 56,000-bps
      links to the other institutions on the network.  Reliability is
      becoming high.

      DECNET addresses consist of 16 bits, 6 specifying an area and 10
      specifying a node within the area.  Since there are only 64
      possible areas, management of the area numbers is very important. 
      Within Easynet, DEC's DECNET-based company network, all area
      numbers are in use; thus direct gateways between Easynet and other
      DECNETs are problematic.

      There are many DECNETs other than SPAN outside of Easynet.  They
      cooperate in assigning area numbers, with SPAN management
      providing a forum, especially for those networks interested in
      joining SPAN (ESA provides a similar forum in Europe).  A major
      task of SPAN's routing centers is the assignment of nodes to
      areas.

      There are currently more than one hundred hosts connected directly
      to SPAN, all of them DEC machines.  Outside of NASA, there are
      many participating universities and laboratories, such as the Los
      Alamos National Laboratory. There are many LANs indirectly
      connected to SPAN.  Because other exiting DECNETs want to join
      SPAN, the total number of hosts is expected to reach five hundred
      within a year.  There is a transatlantic X.25 link between
      Marshall Space Flight Center in Huntsville, Alabama, and ESA's
      Operations Centre (ESOC) in Darmstadt, West Germany.  A 9,600-bps
      link was installed in September from Goddard to Germany, and one
      to Japan is expected by the end of the year.
      {extract from Communications of the ACM, October 1986}    
      {contributed by Walt Lamia}

  <><><><><><><>   VNS Edition : 1410      Friday 25-Sep-1987   <><><><><><><>