Defense Data Network
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The Defense Data Network (DDN) was a separate instantiation of the ARPANET used by the United States Department of Defense from 1983-1995 for its Internet services.
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 Nodes (PSNs) from BBN Technologies as its routers, and BBN performed network planning and management for the network during much of its existence.
[edit] 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 routers.
- 1995 - The Defense Data Network ceased operation.
[edit] 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).
