Defense Information Systems Agency

Formerly the Defense Communications Agency (DCA), the U.S. Defense Information Systems Agency (DISA) continues to manage the strategic communications systems of the U.S., but has taken on an additional role in strategic applications such as the Global Information Grid. It controls the physical networks on which the various enterprise networks, of varying levels of security classification, are mapped as routed networks.

Physical and multiplexed networks
Common user networks are generally independent of the security level, security being enforced at levels overlaid onto them. There has been constant progression in both technology and bandwidth. Within the Defense Information Systems Network (DISN), transmission networks may be terrestrial, satellite or mixtures. Subnetworks of DISN are usually multiplexed or circuit switched, or use hybrid technologies such as Multiprotocol Label Switching:


 * DISN ATM Service (DATMS)
 * IDNX/Promina Network
 * Enhanced SONET (ESONET)
 * DISN CONUS (DISN-C/DATS)
 * DISN Core (SONET/Optical)
 * JHITS Hawaii (JHITS Transport)
 * Digital European Backbone (DEB)
 * Puerto Rico Area Wideband System (PRAWS)

Converged services
Over DISN are networks for data, voice, video.


 * Data
 * NIPRNET, for unclassified but sensitive traffic
 * SIPRNET, carrying classified traffic through the SECRET level; the primary data network for general operations
 * JWICS Joint Worldwide Intelligence Communications System, carrying material of the highest classification levels
 * DISN Leading Edge Services (LES)
 * Video
 * DISN Video Services - Global (DVS-G) for unclassified through basic TOP SECRET information
 * Compartmented control system (i.e., intelligence and special access) video uses JWICS; there are also dedicated intelligence networks, especially for satellites