DECnet was a protocol suite developed by Digital Equipment Corporation (DEC). DECnet was originally designed in 1975 to allow PDP-11 minicomputers to communicate with each other.

DECnet conforms to the Digital Network Architecture (DNA) developed by DEC, which maps to the seven-layer Open Systems Interconnection (OSI) reference model for networking protocols. DECnet is essentially a peer-to-peer networking protocol for all DEC networking environments. DECnet supports various media and link-layer technologies, including Ethernet, Token Ring, and Fiber Distributed Data Interface (FDDI). The current release of DECnet is called Phase V.

DECnet refers to a specific set of hardware and software networking products which implement the DIGITAL Network Architecture (DNA). The DIGITAL Network Architecture has a set of documents which define the network architecture in general, state the specifications for each layer of the architecture and describe the protocols which operate within each layer.

CCNET

CCNET (Computer Center Network) was a DECnet network that connected the campuses of various universities in the eastern regions of the United States during the 1980s. A key benefit was the sharing of systems software developed by the operations staff at the various sites, all of which were using a variety of DEC computers. As of March 1983, it included Columbia University, Carnegie Mellon University, and Case Western Reserve University. By May 1986, New York University, Stevens Institute of Technology, Vassar College and Oberlin College had been added. Several other universities joined later.