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Defense Data Network




The DDN began as the MILNET , a network formed in 1983 when military sites split off the public ARPANET. As a large-scale, private internet, the DDN provided Internet Protocol connectivity across the United States and to US military bases abroad. Throughout the 1980s it expanded as a set of four parallel military networks, each at a different security level. These networks transitioned to become the NIPRNET , SIPRNET , and JWICS networks in the 1990s.

In a manner directly analogous to the ARPANET, the DDN used Packet Switch Node s (PSNs) from BBN Technologies as its routers, and BBN performed network planning and management for the network during much of its existence.


DDN TIMELINE

  • 1982 - BBN Technologies given contract to build and operate a new, worldwide Defense Data Network.


  • 1983 - MILNET , an unclassified, military-only network, split off from the ARPANET, remaining connected only at a small number of Electronic Mail gateways that could be rapidly disconnected if required for security reasons.


  • 1980s - DDN grows from the MILNET to four sub-networks, each at its own security level.


  • 1992 - a study determined that the DDN should be replaced by newer Internet technology, i.e., modern IP Router s.


  • 1995 - The Defense Data Network ceased operation.



DDN SUBNETWORKS

Because the DDN's packet switch nodes were not trusted to simultaneously support traffic of different classification levels ( Multi-level Security ), four worldwide sub-networks were deployed, with packet switches at different classifications physically separated. Classified traffic was encrypted so all traffic could share a common trunking infrastructure.

The four DDN subnetworks were:

  • Military Network (MILNET) for Unclassified traffic

  • Defense Secure Network One (DSNET 1) for Secret traffic

  • Defense Secure Network Two (DSNET 2) for Top Secret traffic

  • Defense Secure Network Three (DSNET 3) for Top Secret/Sensitive Compartmented Information (TS/SCI)


MILNET and DSNET 1 were common user networks, much like the public Internet, but DSNET 2 was dedicated to supporting the Worldwide Military Command And Control System (WWMCCS) and DSNET 3 was dedicated to supporting the DOD Intelligence Information System (DODIIS).


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