Difference between revisions of "DECnet"

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Initially built with four layers, it later (1992) evolved into a seven layer [[Open Systems Interconnection|OSI]] compliant networking protocol, around the time when open systems ([[POSIX]] compliant, i.e. [[UNIX|Unix-like]]) were grabbing marketshare from the proprietary OSes, like VMS.
 
Initially built with four layers, it later (1992) evolved into a seven layer [[Open Systems Interconnection|OSI]] compliant networking protocol, around the time when open systems ([[POSIX]] compliant, i.e. [[UNIX|Unix-like]]) were grabbing marketshare from the proprietary OSes, like VMS.
  
−
DECnet was built right into the DEC flagship operating system [[VMS|VAX/VMS]] since its inception. Digital also ported it to its own [[Ultrix]] variant of [[UNIX]], as well as [[Apple Macintosh]] computers and PCs running both DOS and Windows under the name '''DEC Pathworks''', transforming these systems into DECnet end-nodes in a network of [[VAX]] machines. More recently, an open-source version has been developed for the [[Linux]] OS: see [http://linux-decnet.sourceforge.net/ Linux-DECnet on Sourceforge].
+
DECnet was built right into the DEC flagship operating system [[VMS|VAX/VMS]] since its inception. Digital also ported it to its own [[Ultrix]] variant of [[UNIX]], as well as [[Apple Macintosh]] computers and PCs running both DOS and Windows under the name '''[[DECnet-DOS]]''' (later renamed to '''[[DEC Pathworks]]''', transforming these systems into DECnet end-nodes in a network of [[VAX]] machines. More recently, an open-source version has been developed for the [[Linux]] OS: see [http://linux-decnet.sourceforge.net/ Linux-DECnet on Sourceforge].
  
 
==Brief overview of the evolution of DECnet==
 
==Brief overview of the evolution of DECnet==
  
−
DECnet refers to a specific set of hardware and software networking products which implement the '''DIGITAL Network Architecture''' (DNA).  The DIGITAL Network Architecture is essentially a set of documents which define the network architecture in general, state the specifications for each layer of the architecture, and describe the [[protocol]]s which operate within each layer.  Although [[packet sniffer|network protocol analyzer tools]] tend to categorize all protocols from DIGITAL as "DECnet", strictly speaking, non-routed DIGITAL protocols such as LAT, SCS, AMDS, LAST/LAD are not DECnet protocols and are not part of the DIGITAL Network Architecture.
+
DECnet refers to a specific set of hardware and software networking products which implement the '''DIGITAL Network Architecture''' (DNA).  The DIGITAL Network Architecture is essentially a set of documents which define the network architecture in general, state the specifications for each layer of the architecture, and describe the [[protocol]]s which operate within each layer.  Although [[packet sniffer|network protocol analyzer tools]] tend to categorize all protocols from DIGITAL as "DECnet", strictly speaking, non-routed DIGITAL protocols such as [[LAT]], [[SCS]], [[AMDS]], [[LAST/LAD]] are not DECnet protocols and are not part of the DIGITAL Network Architecture.
  
 
To trace the evolution of DECnet is to trace the development of DNA. The beginnings of DNA were in the early 1970s. DIGITAL published its first DNA specification at about the same time that [[IBM]] announced its [[Systems Network Architecture]] (SNA). Since that time, development of DNA has evolved through the following phases:
 
To trace the evolution of DECnet is to trace the development of DNA. The beginnings of DNA were in the early 1970s. DIGITAL published its first DNA specification at about the same time that [[IBM]] announced its [[Systems Network Architecture]] (SNA). Since that time, development of DNA has evolved through the following phases:
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==='''Phase II''' (1976)===
 
==='''Phase II''' (1976)===
  
−
Support for networks of up to 32 nodes with multiple, different implementations which could interoperate with each other. Implementations expanded to included [[RSTS/E]], [[TOPS-10]],  [[TOPS-20]] and [[VMS]] (from VMS V1.0 / DECnet-VAX V1.0) with communications between processors still limited to point-to-point links only. Introduction of file transfer (FAL), remote file access (DAP), task-to-task programming interfaces and network management features.
+
Support for networks of up to 32 nodes with multiple, different implementations which could interoperate with each other. Implementations expanded to included [[RSTS/E]], [[TOPS-10]],  [[TOPS-20]] and [[VMS]] (from VMS V1.0 / DECnet-VAX V1.0) with communications between processors still limited to point-to-point links only. With Phase II it is not yet possible to send packets to hosts via intermediate nodes, only to hosts that are directly connected to the sender. Introduction of file transfer (FAL), remote file access (DAP), task-to-task programming interfaces and network management features.
  
 
==='''Phase III''' (1980)===
 
==='''Phase III''' (1980)===
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|----- align="left"
 
|----- align="left"
 
! Data link
 
! Data link
−
| DDCMP: Digital Data Communications Message Protocol<br>[[Ethernet]], [[IBM token ring|Token ring]], [[HDLC]], [[Fiber distributed data interface|FDDI]], ...
+
| DDCMP: Digital Data Communications Message Protocol<br>[[Computer Interconnect|CI]], [[Ethernet]], [[IBM token ring|Token ring]], [[HDLC]], [[Fiber distributed data interface|FDDI]], ...
 
|----- align="left"
 
|----- align="left"
 
! Physical
 
! Physical
−
| [[Ethernet]], [[IBM token ring|Token ring]], [[Fiber distributed data interface|FDDI]], ...
+
| [[Computer Interconnect|CI]], [[Ethernet]], [[IBM token ring|Token ring]], [[Fiber distributed data interface|FDDI]], ...
 
|}
 
|}
 
</div>
 
</div>
  
−
==='''Phase IV''' and '''Phase IV+''' (1982)===
+
==='''Phase IV''' (1982) and '''Phase IV+''' (1983)===
  
−
Phase IV was released initially to RSX-11 and VMS systems, later TOPS-20, TOPS-10, ULTRIX, [[VAXELN]], and RSTS/E gained support. Support for networks of up to 64,449 nodes (63 areas of 1023 nodes), datalink capabilities expanded beyond DDCMP to include [[Ethernet]] [[local area network]] support as the datalink of choice, expanded adaptive routing capability to include hierarchical routing (areas, level 1 and level 2 routers), [[VMScluster]] support (cluster alias) and host services (CTERM).
+
Phase IV was released initially to RSX-11 and VMS systems (from VMS V3.4 / DECnet-VAX V3.1), later TOPS-20, TOPS-10, ULTRIX, [[VAXELN]], and RSTS/E gained support. Support for networks of up to 255 nodes, datalink capabilities expanded beyond [[DDCMP]] to include [[Computer Interconnect|CI]] (VMS only) and [[Ethernet]] [[local area network]] support as the datalink of choice, expanded adaptive routing capability to include hierarchical routing (areas, level 1 and level 2 routers), [[VMScluster]] support (cluster alias) and host services (CTERM).
  
 
CTERM allowed a user on one computer to log into another computer remotely, performing the same function that [[Telnet]] does in the [[TCP/IP]] protocol stack. Digital also released a product called the PATHWORKS client, and more commonly known as the PATHWORKS 32 client, that implemented much of DECnet Phase IV for DOS, and 16 and 32 bit Microsoft Windows platforms (all the way through to Windows Server 2003).
 
CTERM allowed a user on one computer to log into another computer remotely, performing the same function that [[Telnet]] does in the [[TCP/IP]] protocol stack. Digital also released a product called the PATHWORKS client, and more commonly known as the PATHWORKS 32 client, that implemented much of DECnet Phase IV for DOS, and 16 and 32 bit Microsoft Windows platforms (all the way through to Windows Server 2003).
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Enhancements made to DECnet Phase IV eventually became known as DECnet Phase IV+, although systems running this protocol remained completely interoperable with DECnet Phase IV systems.
 
Enhancements made to DECnet Phase IV eventually became known as DECnet Phase IV+, although systems running this protocol remained completely interoperable with DECnet Phase IV systems.
 +
 +
Phase IV+ (e.g. from VMS 4.0 / DECnet-VAX V4.0) added Support for networks of up to 64,449 nodes (63 areas of 1023 nodes).
  
 
==='''Phase V''' and '''Phase V+''' (1987)===
 
==='''Phase V''' and '''Phase V+''' (1987)===
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It was later renamed '''DECnet/OSI''' to emphasize its OSI interconnectibility, and subsequently '''DECnet-Plus''' as TCP/IP protocols were incorporated.
 
It was later renamed '''DECnet/OSI''' to emphasize its OSI interconnectibility, and subsequently '''DECnet-Plus''' as TCP/IP protocols were incorporated.
 +
 +
=== DECnet Phases Interoperability ===
 +
 +
Phase II, III, and IV nodes can all exist on a network. The following types of nodes can be configured as being adjacent to each other:
 +
* Phase II/Phase II
 +
* Phase II/Phase III
 +
* Phase III/Phase III
 +
* Phase III/Phase IV
 +
* Phase IV/Phase IV
 +
* Phase V/? (to be determined)
 +
 +
==DECnet Versions, Manuals and Software Product Descriptions==
 +
 +
===DECnet-VAX===
 +
* DECnet-VAX V1.0
 +
** [https://archive.org/details/bitsavers_decspd25.0_392688 AE-D624B-TE SPD 25.03.01 DECnet-VAX Version 1.pdf]
 +
 +
* DECnet-VAX V1.3
 +
** AE-D624E-TE SPD 25.3.4 DECnet-VAX, Version 1.3
 +
 +
* DECnet-VAX V3.0
 +
** [http://bitsavers.org/pdf/dec/vax/vms/3.0/AA-H802B-TE_DECnet-VAX_3.0_Users_Guide_198205.pdf AA-H802B-TE DECnet-VAX User's Guide]
 +
 +
* DECnet-VAX V3.1
 +
** AA-H803C-TE DECnet-VAX System Manager's Guide
 +
 +
* DECnet-VAX V4.x
 +
** [https://archive.org/details/stx_AA-Y512C-TE_VMS_4.4_VAX_VMS_Networking_Manual_Apr86 AA-Y512C-TE VAX/VMS Networking Manual]
 +
** [https://archive.org/details/stx_AA-Z425C-TE_VMS_4.4_VAX_VMS_Network_Control_Program_Reference_Manual_Apr86 AA-Z425C-TE VAX/VMS Network Control Program Reference Manual]
 +
 +
* DECnet-VAX V5.x
 +
** [http://bitsavers.org/pdf/dec/vax/vms/5.0/AA-LA50A-TE_VMS_5.0_Network_Control_Program_Manual_198804.pdf AA-LA50A-TE VMS Network Control Program Manual]
 +
** [http://bitsavers.org/pdf/dec/vax/vms/5.0/AA-LA47A-TE_Guide_to_DECnet-VAX_Networking_5.0_198804.pdf AA-LA47A-TE Guide to DECnet-VAX Networking]
 +
** [http://bitsavers.org/pdf/dec/vax/vms/5.0/AA-LA48A-TE_VMS_5.0_Networking_Manual_198804.pdf AA-LA48A-TE VMS Networking Manual]
 +
** [http://bitsavers.org/pdf/dec/vax/vms/SPD/AE-D624Z-TE_DECnet-VAX_V5.1_SPD_25.03.25_Jan89.pdf AE-D624Z-TE DECnet-VAX Version 5.1 SPD 25.03.25]
 +
** [http://bitsavers.org/pdf/dec/vax/vms/5.4/Release_Notes/AE-NJ32C-TE_DECnet-VAX_Version_5.4_SPD_25.03.28_Aug1990.pdf AE-NJ32C-TE DECnet-VAX Version 5.4 SPD 25.03.28]
 +
 +
* DECnet-VAX V6.0:
 +
** [http://www.vaxhaven.com/images/0/09/AA-PV60A-TK.pdf AA-PV60A-TK DECnet for OpenVMS Networking Manual]
 +
** [https://www.digiater.nl/openvms/doc/alpha-v8.3/83final/documentation/pdf/DECNET_OVMS_GD_Network.PDF AA-PV5ZA-TK DECnet for OpenVMS Guide to Networking]
 +
** [https://www.digiater.nl/openvms/doc/alpha-v8.3/83final/documentation/pdf/DECNET_OVMS_NET_UTIL.PDF AA-PV61A-TK DECnet for OpenVMS Network Management Utilities]
 +
 +
* DECnet-VAX V8.4:
 +
** [https://vmssoftware.com/docs/VSI_DECnet_IV_Network_Util_Ref.pdf DO-DNTNMU-01A VSI OpenVMS DECnet Network Management Utilities]
 +
 +
===DECnet-11M===
 +
* DECnet-11M V2.0
 +
** [https://usermanual.wiki/Document/1075057802DECnet11M.2303482373/view AE-3431F-TC DECnet-11M SPD 10.75.05]
 +
 +
* DECnet-11M V4.0 / DECnet-11M-PLUS V2.0
 +
** AA-H224C-TC DECnet-RSX System Manager's Guide
 +
** AA-X924A-TC DECnet-RSX System Manager's Minireference Guide
 +
** AA-J517C-TC DECnet-RSX Release Notes
 +
 +
* DECnet-11M V4.2 / RSX-11M-PLUS V3.0
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.2_Sep85/AA-J517D-TC_DECnet-RSX_Release_Notes_Sep85.pdf AA-J517D-TC DECnet-RSX Release Notes]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.2_Sep85/AA-EB30A-TC_DECnet-RSX_Guide_to_Network_Management_Utilities_Sep85.pdf AA-EB30A-TC DECnet-RSX Guide to Network Management Utilities]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.2_Sep85/AA-EB29A-TC_DECnet-RSX_Network_Management_Concepts_and_Procedures_Sep85.pdf AA-EB29A-TC DECnet-RSX Network Management Concepts and Procedures]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.2_Sep85/AA-M098C-TC_DECnet-RSX_Programmers_Reference_Manual_Sep85.pdf AA-M098C-TC DECnet-RSX Programmers Reference Manual]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.2_Sep85/AA-H223D-TC_DECnet-RSX_Guide_to_User_Utilities_Sep85.pdf AA-H223D-TC DECnet-RSX Guide to User Utilities]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.2_Sep85/AA-H225D-TC_DECnet-RSX_Network_Generation_and_Installation_Guide_Sep85.pdf AA-H225D-TC DECnet-RSX Network Generation and Installation Guide]
 +
 +
* DECnet-11M V4.3 / DECnet-11M-PLUS V4.0
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.3_Oct87/AA-EB28B-TC_DECnet-RSX_Network_Management_Concepts_and_Procedures_Oct87.pdf AA-EB28B-TC DECnet-RSX Network Management Concepts and Procedures]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.3_Oct87/AA-H223E-TC_DECnet-RSX_Guide_to_User_Utilities_Oct87.pdf AA-H223E-TC DECnet-RSX Guide to User Utilities]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.3_Oct87/AA-H225E-TC_DECnet-RSX_Network_Generation_and_Installation_Guide_Oct87.pdf AA-H225E-TC DECnet-RSX Network Generation and Installation Guide]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.3_Oct87/AA-J517E-TC_DECnet-RSX_Release_Notes_Oct87.pdf AA-J517E-TC DECnet-RSX Release Notes]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.3_Oct87/AA-M098D-TC_DECnet-RSX_Programmers_Reference_Manual_Oct87.pdf AA-M098D-TC DECnet-RSX Programmers Reference Manual]
 +
 +
* DECnet-11M V4.5 / DECnet-11M-PLUS V4.3
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.5_Oct89/AA-EB28C-TC_DECnet-RSX_V4.5_Network_Management_Concepts_and_Procedures_Oct89.pdf AA-EB28C-TC DECnet-RSX Network Management Concepts and Procedures]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.5_Oct89/AA-EB30C-TC_DECnet-RSX_V4.5_Guide_to_Network_Management_Utilities_Oct89.pdf AA-EB30C-TC DECnet-RSX Guide to Network Management Utilities]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.5_Oct89/AA-H223F-TC_DECnet-RSX_V4.5_Guide_to_User_Utilities_Oct89.pdf AA-H223F-TC DECnet-RSX Guide to User Utilities]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.5_Oct89/AA-H225F-TC_DECnet-RSX_V4.5_Network_Generation_and_Installation_Guide_Oct89.pdf AA-H225F-TC DECnet-RSX Network Generation and Installation Guide]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.5_Oct89/AA-J517F-TC_DECnet-RSX_V4.5_Supplemental_Information_and_Release_Notes_Oct89.pdf AA-J517F-TC DECnet-RSX Supplemental Information and Release Notes]
 +
**[http://bitsavers.org/pdf/dec/decnet/decnetRSX/4.5_Oct89/AA-M098E-TC_DECnet-RSX_V4.5_Programmers_Reference_Manual_Oct89.pdf AA-M098E-TC DECnet-RSX Programmers Reference Manual]
 +
 +
* DECnet-11M V4.8 / DECnet-11M-PLUS V4.6
 +
** [http://mim.update.uu.se/manuals/network/decnet6.pdf AA-J517K-TC DECnet-RSX Supplemental Information and Release Notes]
 +
** [http://www.bitsavers.org/pdf/dec/pdp11/rsx11/SPD/AE-J513N-TC_DECnet-11M-PLUS_V4.6_SPD_10.66.12_Feb99.pdf AE-J513N-TC DECnet-11M-PLUS, Version 4.6 SPD 10.66.12]
 +
 +
===DECnet/E===
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* DECnet/E V1.0
 +
** [http://www.bitsavers.org/pdf/dec/spd/10.73.02_7808_DECnetE.pdf AE-D427B-TC DECnet/E, Version 1.0 SPD 10.73.02]
 +
 +
* DECnet/E V2.0
 +
** [http://www.bitsavers.org/pdf/dec/pdp11/rsts/DECnetE/AA-H505B-TC_DECnet-E_V2.0_System_Managers_Guide_Jan82.pdf AA-H505B-TC DECnet/E System Manager's Guide]
 +
 +
===PRO/DECnet===
 +
* PRO/DECnet V2.1
 +
 +
===DECnet-DOS===
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* DECnet-DOS V1.1
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetDOS/DECnet-DOS_V1.1_Release_Note.txt DECnet-DOS Release Notes]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetDOS/AA-GV32A-TV_DECnet-DOS_V1.1_Mini-Reference_Guide_Apr86.pdf AA-GV32A-TV DECnet-DOS Mini-Reference Guide]
 +
** [http://bitsavers.org/pdf/dec/decnet/decnetDOS/AA-EB46B-TV_DECnet-DOS_Programmers_Reference_Manual_Apr86.pdf AA-EB46B-TV DECnet-DOS Programmer's Reference Manual]
 +
 +
* DECnet-DOS V3.0
 +
** AA-PAFFA-TK DECnet-DOS Getting Started
 +
 +
===DECnet-ULTRIX===
 +
* DECnet-ULTRIX V1.1
 +
** DECnet Ultrix V1.1 Release Notes
 +
 +
* DECnet-ULTRIX V2.0
 +
** AA-EE38C-TE ULTRIX-32 DECnet Network Management
 +
 +
* DECnet/ULTRIX V3.0
 +
** AA-JD82D-TE DECnet-ULTRIX Release Notes
 +
** BH-EA86G-TE DECnet/ULTRIX Version 3.0 and 3.0a SPD 26.83.06
 +
** AA-EA87D-TE DECnet-ULTRIX Installation Guide
 +
** AA-EA88C-TE DECnet-ULTRIX User's and Programmer's Guide
 +
 +
* DECnet-ULTRIX V4.0
 +
** [https://archive.org/download/h42_DEC_DECnet_Ultrix/DEC_DECnet_Ultrix.pdf AA-EE38D-TE DECnet Ultrix Network Management]
 +
** [https://ia800704.us.archive.org/26/items/h42_DEC_DECnet_Ultrix/DEC_DECnet_Ultrix.pdf AA-JD82E-TE DECnet-ULTRIX Release Notes]
 +
** [https://ia902801.us.archive.org/9/items/bitsavers_decvaxultrAAPB62ATEDECnetUltrix4.0NCPCommandRefere_4966828/AA-PB62A-TE_DECnet_Ultrix_4.0_NCP_Command_Reference_May1990.pdf AA-PB62A-TE_DECnet-Ultrix NCP Command Reference]
 +
** [http://www.bitsavers.org/pdf/dec/vax/ultrix-32/DECnet_Ultrix_4.0/SPD268308_DECnet_Ultrix_4.0_May1990.pdf AE-EA86J-TE DECnet-Ultrix Version 4.0 SPD 26.83.08]
 +
 +
* DECnet-ULTRIX V4.2
 +
** DECnet-ULTRIX Release Notes V4.2
 +
 +
===DECnet-RT===
 +
* DECnet-RT V1.0
 +
** [http://www.bitsavers.org/pdf/dec/spd/10.72.01_7802_DECnet-RT.pdf DECnet-RT Version 1.0 SPD 10.72.01]
 +
 +
* DECnet-RT V1.1
 +
** SPD10.72.4 DECnet-RT V1.1.pdf
 +
** SPD10.72.5 DECnet-RT V1.1.pdf
 +
 +
* DECnet-RT V2.0
 +
** SPD10.72.7 DECnet-RT V2.0.pdf
 +
** SPD10.72.8 DECnet-RT V2.0.pdf
 +
 +
===DECnet/8===
 +
* DECnet/8 V1.0
 +
** 06.01.01_7705_DECNET8.pdf
 +
 +
===DECnet-10===
 +
* DECnet-10 V2.0
 +
** 08.60.01_7712_DECnet-10.pdf
 +
 +
===DECnet-20===
 +
* DECnet-20 V1.0
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** 23.02.00_7809_DECnet-20_V1.pdf
 +
 +
* DECnet-20 V2.0
 +
** AA-5091B-TM_TOPS-20_DECnet-20_Programmers_Guide_Jan80.pdf
 +
 +
===DECnet-11D===
 +
* DECnet-11D V2.0
 +
** 10.70.05_7806_DECnet-11D.pdf
 +
 +
===DECnet-11S===
 +
* DECnet-11S V2.0
 +
** 10.74.05_7802_DECnet-11S.pdf
 +
 +
===DECnet-IAS===
 +
* DECnet-IAS V2.0
 +
** 10.71.03_7802_DECnet-IAS.pdf
  
 
==References==
 
==References==
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==Related articles and practical guides==
 
==Related articles and practical guides==
  
 +
* [[DECnet Routing and DECnet Router]]
 
* [[DECnet on VMS]]
 
* [[DECnet on VMS]]
−
 
 
* [[DECnet on RSX-11M]]
 
* [[DECnet on RSX-11M]]
−
 
 
* [[DECnet on RSTS/E]]
 
* [[DECnet on RSTS/E]]
 +
* [[Installing, Configuring, and Testing DECnet V1.3 on VMS V2.0]]
  
−
[[Category:Network Protocols]]
+
[[Category: Network Protocols]]
−
[[Category:DECnet]]
+
[[Category: DECnet]]

Latest revision as of 08:32, 16 October 2024

DECnet is a proprietary suite of network protocols created by DEC, originally released in 1975 in order to connect two PDP-11 minicomputers. It evolved into one of the first peer-to-peer network architectures, thus transforming DEC into a networking powerhouse in the 1980s.

Initially built with four layers, it later (1992) evolved into a seven layer OSI compliant networking protocol, around the time when open systems (POSIX compliant, i.e. Unix-like) were grabbing marketshare from the proprietary OSes, like VMS.

DECnet was built right into the DEC flagship operating system VAX/VMS since its inception. Digital also ported it to its own Ultrix variant of UNIX, as well as Apple Macintosh computers and PCs running both DOS and Windows under the name DECnet-DOS (later renamed to DEC Pathworks, transforming these systems into DECnet end-nodes in a network of VAX machines. More recently, an open-source version has been developed for the Linux OS: see Linux-DECnet on Sourceforge.

Brief overview of the evolution of DECnet

DECnet refers to a specific set of hardware and software networking products which implement the DIGITAL Network Architecture (DNA). The DIGITAL Network Architecture is essentially 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. Although network protocol analyzer tools tend to categorize all protocols from DIGITAL as "DECnet", strictly speaking, non-routed DIGITAL protocols such as LAT, SCS, AMDS, LAST/LAD are not DECnet protocols and are not part of the DIGITAL Network Architecture.

To trace the evolution of DECnet is to trace the development of DNA. The beginnings of DNA were in the early 1970s. DIGITAL published its first DNA specification at about the same time that IBM announced its Systems Network Architecture (SNA). Since that time, development of DNA has evolved through the following phases:

Phase I (1974)

Support limited to 2 PDP-11s running the RSX-11 operating system only, with communication over point-to-point (DDCMP) links between nodes.

Phase II (1976)

Support for networks of up to 32 nodes with multiple, different implementations which could interoperate with each other. Implementations expanded to included RSTS/E, TOPS-10, TOPS-20 and VMS (from VMS V1.0 / DECnet-VAX V1.0) with communications between processors still limited to point-to-point links only. With Phase II it is not yet possible to send packets to hosts via intermediate nodes, only to hosts that are directly connected to the sender. Introduction of file transfer (FAL), remote file access (DAP), task-to-task programming interfaces and network management features.

Phase III (1980)

Support for networks of up to 255 nodes over point-to point and multi-drop links for VMS (from VMS V3.0 / DECnet-VAX V3.0) and other DEC operating systems. Introduction of adaptive routing capability, downline loading (MOP), record access, a network management architecture, and gateways to other types of networks including IBM’s SNA and CCITT Recommendation X.25.

DECnet Phase IV protocol suite
Application DAP: Data Access Protocol

CTERM: Command Terminal

Network Management NICE: Network Management protocol

MOP: Maintenance Operation Protocol

Session SCP: Session Control Protocol
Transport NSP: Network Service Protocol
Network DRP: DECnet Routing Protocol
Data link DDCMP: Digital Data Communications Message Protocol
CI, Ethernet, Token ring, HDLC, FDDI, ...
Physical CI, Ethernet, Token ring, FDDI, ...

Phase IV (1982) and Phase IV+ (1983)

Phase IV was released initially to RSX-11 and VMS systems (from VMS V3.4 / DECnet-VAX V3.1), later TOPS-20, TOPS-10, ULTRIX, VAXELN, and RSTS/E gained support. Support for networks of up to 255 nodes, datalink capabilities expanded beyond DDCMP to include CI (VMS only) and Ethernet local area network support as the datalink of choice, expanded adaptive routing capability to include hierarchical routing (areas, level 1 and level 2 routers), VMScluster support (cluster alias) and host services (CTERM).

CTERM allowed a user on one computer to log into another computer remotely, performing the same function that Telnet does in the TCP/IP protocol stack. Digital also released a product called the PATHWORKS client, and more commonly known as the PATHWORKS 32 client, that implemented much of DECnet Phase IV for DOS, and 16 and 32 bit Microsoft Windows platforms (all the way through to Windows Server 2003).

Phase IV implemented an 8 layer architecture similar to the OSI (7 layer) model especially at the lower levels (see diagram below). Since the OSI standards were not yet fully developed at the time, many of the Phase IV protocols remained proprietary.

The Ethernet implementation was unusual in that the software changed the physical address of the Ethernet interface on the network to AA-00-04-00-xx-yy where xx-yy reflected the DECnet network address of the host. This allowed router-less LAN operation because the LAN address could be deduced from the DECnet address. This precluded connecting two NICs from the same DECnet node onto the same LAN segment, however.

The initial implementations released were for VMS and RSX-11, later this expanded to virtually every operating system DIGITAL ever shipped with the notable exception of RT-11. DECnet stacks are found on Linux, SunOS and other platforms, and Cisco and other network vendors offer products that can cooperate with and operate within DECnet networks. Full DECnet Phase IV specifications are available.

At the same time that DECnet Phase IV was released, the company also released a proprietary protocol called LAT for serial terminal access via Terminal servers. LAT is entirely separate from DECnet, though many DECserver LAT terminal servers did use MOP for the server image download and related bootstrap processing.

Enhancements made to DECnet Phase IV eventually became known as DECnet Phase IV+, although systems running this protocol remained completely interoperable with DECnet Phase IV systems.

Phase IV+ (e.g. from VMS 4.0 / DECnet-VAX V4.0) added Support for networks of up to 64,449 nodes (63 areas of 1023 nodes).

Phase V and Phase V+ (1987)

Support for very large (architecturally unlimited) networks, a new network management model, local or distributed name service, improved performance over Phase IV. Move from a proprietary network to an Open Systems Interconnection (OSI) by integration of ISO standards to provide multi-vendor connectivity and compatibility with DNA Phase IV, the last two features resulted in a hybrid network architecture (DNA and OSI) with separate “towers” sharing an integrated transport layer. Transparent transport level links to TCP/IP were added via the IETF RFC 1006 (OSI over IP) and RFC 1859 (NSP over IP) standards (see diagram below).

It was later renamed DECnet/OSI to emphasize its OSI interconnectibility, and subsequently DECnet-Plus as TCP/IP protocols were incorporated.

DECnet Phases Interoperability

Phase II, III, and IV nodes can all exist on a network. The following types of nodes can be configured as being adjacent to each other:

  • Phase II/Phase II
  • Phase II/Phase III
  • Phase III/Phase III
  • Phase III/Phase IV
  • Phase IV/Phase IV
  • Phase V/? (to be determined)

DECnet Versions, Manuals and Software Product Descriptions

DECnet-VAX

  • DECnet-VAX V1.3
    • AE-D624E-TE SPD 25.3.4 DECnet-VAX, Version 1.3
  • DECnet-VAX V3.1
    • AA-H803C-TE DECnet-VAX System Manager's Guide

DECnet-11M

  • DECnet-11M V4.0 / DECnet-11M-PLUS V2.0
    • AA-H224C-TC DECnet-RSX System Manager's Guide
    • AA-X924A-TC DECnet-RSX System Manager's Minireference Guide
    • AA-J517C-TC DECnet-RSX Release Notes

DECnet/E

PRO/DECnet

  • PRO/DECnet V2.1

DECnet-DOS

  • DECnet-DOS V3.0
    • AA-PAFFA-TK DECnet-DOS Getting Started

DECnet-ULTRIX

  • DECnet-ULTRIX V1.1
    • DECnet Ultrix V1.1 Release Notes
  • DECnet-ULTRIX V2.0
    • AA-EE38C-TE ULTRIX-32 DECnet Network Management
  • DECnet/ULTRIX V3.0
    • AA-JD82D-TE DECnet-ULTRIX Release Notes
    • BH-EA86G-TE DECnet/ULTRIX Version 3.0 and 3.0a SPD 26.83.06
    • AA-EA87D-TE DECnet-ULTRIX Installation Guide
    • AA-EA88C-TE DECnet-ULTRIX User's and Programmer's Guide
  • DECnet-ULTRIX V4.2
    • DECnet-ULTRIX Release Notes V4.2

DECnet-RT

  • DECnet-RT V1.1
    • SPD10.72.4 DECnet-RT V1.1.pdf
    • SPD10.72.5 DECnet-RT V1.1.pdf
  • DECnet-RT V2.0
    • SPD10.72.7 DECnet-RT V2.0.pdf
    • SPD10.72.8 DECnet-RT V2.0.pdf

DECnet/8

  • DECnet/8 V1.0
    • 06.01.01_7705_DECNET8.pdf

DECnet-10

  • DECnet-10 V2.0
    • 08.60.01_7712_DECnet-10.pdf

DECnet-20

  • DECnet-20 V1.0
    • 23.02.00_7809_DECnet-20_V1.pdf
  • DECnet-20 V2.0
    • AA-5091B-TM_TOPS-20_DECnet-20_Programmers_Guide_Jan80.pdf

DECnet-11D

  • DECnet-11D V2.0
    • 10.70.05_7806_DECnet-11D.pdf

DECnet-11S

  • DECnet-11S V2.0
    • 10.74.05_7802_DECnet-11S.pdf

DECnet-IAS

  • DECnet-IAS V2.0
    • 10.71.03_7802_DECnet-IAS.pdf

References

  • Carl Malamud, Analyzing DECnet/OSI Phase V. Van Hostrand 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.
  • DECnet Phase IV OpenVMS manuals for DECnet Phase IV; these Phase IV manuals are archived on OpenVMS Freeware V5.0 distribution, at http://www.hp.com/go/openvms/freeware and other sites.

See also

  • HECnet, a hobbyist DECnet bridged over IP.

Related articles and practical guides

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