DECnet
DECnet is a homogeneous local network that the Digital Equipment Corporation (DEC for short) introduced in 1975 to network their minicomputers . It consists of a number of network protocols collectively referred to as DIGITAL Network Architecture ( DNA ). DECnet was made compatible with Ethernet , X.25 and IBM's SNA , so that the DEC computers can be networked with computers from other manufacturers.
DECnet digitally ported to Ultrix , the Apple Macintosh and IBM-compatible PC with DOS or Windows under the product name DEC Pathworks (later also Advanced Server). These systems are integrated into a VAX network as DECnet end nodes . An open source implementation for the free Linux operating system also exists.
Development history
- 1974: Phase I - limited to two directly connected PDP-11s under RSX-11
- 1976: Phase II - networks with up to 32 nodes, support for TOPS-10 , TOPS-20 and RSTS / E
- 1980: Phase III - networks with up to 255 nodes
- 1982: Phase IV - networks with up to 64,449 nodes (63 areas with 1023 nodes each), for the RSX-11 and VMS operating systems
- 1987: Phase V - support for very large networks (unlimited number of nodes)
Logs
In addition to Ethernet, DECnet also uses the in-house DDCMP (Digital Data Communications Message Protocol) on Layer 2 ( OSI model ) , which is functionally very similar to HDLC , but differs from it in formats and processes. For layers 3 and 4 there is the summarizing NSP (Network Service Protocol) , which also contains functions for establishing and clearing connections , for routing , for flow control and for troubleshooting (e.g. the Maintenance Operations Protocol , MOP). The three lower DECnet layers are collectively referred to as the transport subsystem. On top of it sits a dialog layer with user-oriented services such as file transfer .
- DECnet Phase IV protocol stack
| application | Network application - DAP: Data Access Protocol, CTERM: Command Terminal | Network management | |||
| presentation | Network application - NICE: Network Information Control Exchange, MOP: Maintenance Operation Protocol | ||||
| meeting | Session control - SCP: Session Control Protocol | ||||
| transport | End Communications - NSP: Network Service Protocol | ||||
| network | Routing - DRP: DECnet Routing Protocol | ||||
| DataLink | DataLink - Ethernet or DDCMP: Digital Data Communications Message Protocol | ||||
| Physical | Physical | ||||
See also
literature
- Carl Malamud, Analyzing DECnet / OSI Phase V . Van Nostrand Reinhold, 1991. ISBN 0-442-00375-7 .
- James Martin, Joe Leben, DECnet Phase V: An OSI Implementation . Digital Press, 1992. ISBN 1-55580-769-0 .
Web links
- DECnet Phase IV Specifications
- DECnet Phase IV OpenVMS - Manuals for DECnet Phase IV
- DECnet-Plus - Manuals for OpenVMS
Individual evidence
- ↑ Archived copy ( Memento of the original from June 14, 2008 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
