The DECnet Protocols
- DECnet protocols allow high-speed network connectionscomputer technology image by Raimundas from Fotolia.com
DECnet protocols were developed by the Digital Equipment Corporation (DEC) in 1975 to allow two or more DEC PDP-11 computers to communicate with each other. DEC networking protocols evolved into one of the earliest network architectures to link computers in peer to peer (PDP-11 to PDP-11) configurations. The protocols allowed DEC computers in local and wide area networks to communicate at high speeds. Original networks were engineered in four tiers, eventually evolving to nine layers. - Information is transferred among DECnet units by a routing protocol (RP). Data is distributed on two basic levels. One level routes information within a DECnet hosting area and a second level deals with routing among areas.
- DECnet includes a utility for moving system software up or down in the computer architecture. The Maintenance Operation Protocol also provides troubleshooting, problem diagnosis and testing from remote locations.
- Efficiently engineered networks need trustworthy connections to the Routing Protocol (RP) layer. The Network Services Protocol (NSP) provides this connection coupled with flow control.
- DECnet relies upon SCP (Session Control Protocol) to establish, manage and maintain logical links between host computers.
- Remote files access systems that support DECnet networks using the Data Access Protocol (DAP). This protocol allows files to be created, extended, opened or renamed. It provides across-the-board control information about the file system.
- Command terminal connection between DEC terminals and operating systems is provided by Command Terminal (CTERM). This function allows DEC VMS and RSTS/E to communicate.
- Traffic to and from time sharing hosts is handled and controlled with the Local Area Transport (LAT) protocol. The LAT is engineered to handle multiplexed traffic.
- To prevent logical looping in the network DEC developed the Spanning Tree Protocol (STP). Using an 802.1d MAC Bridge Management Protocol (BMP), it provides data relating to the bridge topology.
- Clustered DEC VAX computers need to intercommunicate. The (LAVC) Local Area Vax Cluster protocol enables this communication among VAX units.
- The suite of protocols developed by Digital Equipment Corporation is now part of the Hewlett Packard Open VMS. Two versions of the DECnet remain in wide usage: Phase IV DECnet and DECnet Plus. Phase IV DECnet uses a seven-layer approach to services. DECnet Plus is backward compatible with DECnet Phase IV and supports multiple protocols.
