Network Control Protocol (ARPANET)

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The Network Control Protocol (NCP) was a communication protocol for a computer network in the 1970s and early 1980s. It provided the transport layer of the protocol stack running on host computers of the ARPANET, the predecessor to the modern Internet.

Contents

NCP preceded the Transmission Control Protocol (TCP) as a transport layer protocol used during the early ARPANET. NCP was a simplex protocol that utilized two port numbers, establishing two connections for two-way communications. An odd and an even port were reserved for each application layer application or protocol. The standardization of TCP and UDP reduced the need for the use of two simplex ports per application to one duplex port. [1] : 15 

There is some confusion over the name, even among the engineers who worked with the ARPANET. [2] Originally, there was no need for a name for the protocol stack as a whole, so none existed. When the development of TCP started, a name was required for its predecessor, and the pre-existing acronym 'NCP' (which originally referred to Network Control Program, the software that implemented this stack) was organically adopted for that use. [3] [4] Eventually, it was realized that the original expansion of that acronym was inappropriate for its new meaning, so a new quasi-backronym was created, 'Network Control Protocol' — again, organically, not via a formal decision. [5] [6]

History

On the ARPANET, the protocols in the physical layer, the data link layer, and the network layer used within the network were implemented on separate Interface Message Processors (IMPs). The host usually connected to an IMP using another kind of interface, with different physical, data link, and network layer specifications. The IMP's capabilities were specified by the Host/IMP Protocol in BBN Report 1822, which was written by Bob Kahn. [7] [8]

Under the auspices of Leonard Kleinrock at University of California Los Angeles (UCLA), [9] Stephen D. Crocker, then a graduate student in computer science at UCLA, formed and led the Network Working Group (NWG). Working with Jon Postel and others, they designed a host-to-host protocol, known as the Network Control Program, which was developed in the ARPANET's earliest RFC documents in 1969 after a series of meetings on the topic with engineers from UCLA, University of Utah, and SRI. [10] [nb 1] Crocker said "While much of the development proceeded according to a grand plan, the design of the protocols and the creation of the RFCs was largely accidental." [nb 2] After approval by Barry Wessler at ARPA, [11] who had ordered certain more exotic elements to be dropped, [12] it was finalized in RFC  33 in early 1970, [13] and deployed to all nodes on the ARPANET in December 1970. [14] [15]

NCP codified the ARPANET network interface, making it easier to establish, and enabling more sites to join the network. [16] [17] It provided connections and flow control between processes running on different ARPANET host computers. Application services, such as remote login and file transfer, would be built on top of NCP, using it to handle connections to other host computers. Other participants in the NWG developed these application-level protocols, TELNET and FTP. [nb 3] [18] [19]

Since lower protocol layers were provided by the IMP-host interface, NCP essentially provided a transport layer consisting of the ARPANET Host-to-Host Protocol (AHHP) and the Initial Connection Protocol (ICP). AHHP defined procedures to transmit a unidirectional, flow-controlled data stream between two hosts. The ICP defined the procedure for establishing a bidirectional pair of such streams between a pair of host processes. Application protocols (e.g., FTP) accessed network services through an interface to the top layer of NCP — a forerunner to the Berkeley sockets interface.

Network Control Program

Network Control Program (usually given as NCP) was the name for the software on hosts which implemented the Network Control Protocol of the ARPANET. [20] [5]

It was almost universally referred to by the acronym, NCP. This was later taken over to refer to the protocol suite itself. [3] [4]

NCPs were written for many operating systems, including Multics, TENEX, UNIX and TOPS-10, and many of those NCPs survive (although of course they are now used by only vintage computer enthusiasts).

Transition to TCP/IP

On January 1, 1983, in what is known as a flag day , NCP was officially rendered obsolete when the ARPANET changed its core networking protocols from NCP to the more flexible and powerful TCP/IP protocol suite, marking the start of the modern Internet. [21] [22] [23] [24]

See also

Notes

  1. ↑ Crocker said "NCP" later came to be used as the name for the protocol, but it originally meant the program within the operating system that managed connections. The protocol itself was known blandly only as the host-host protocol.'
  2. ↑ RFCs began as informal technical notes, "requests for comments", of the Networking Working Group (NWG).
  3. ↑ The NPL team also envisaged the need for levels of data transmission in 1968. Both were early examples of the protocol layering concept incorporated in the OSI model.

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References

  1. ↑ Stevens, W. Richard (1994). TCP/IP Illustrated Volume I. Vol. 1. Reading, Massachusetts, USA: Addison-Wesley Publishing Company. ISBN   0-201-63346-9.
  2. ↑ Crocker, Stephen (27 June 2022). "Separation of TCP and IP". elists.isoc.org. Retrieved 5 August 2022.
  3. 1 2 "Internetting or Beyond NCP" (PDF). Retrieved 4 August 2022.
  4. 1 2 Proposed Revisions to the TCP (PDF). IEN 18. Retrieved 4 August 2022.
  5. 1 2 Reynolds, J.; Postel, J. (1987). The Request For Comments Reference Guide. doi: 10.17487/RFC1000 . RFC 1000. Over the next few months we designed a symmetric host-host protocol, and we defined an abstract implementation of the protocol known as the Network Control Program. ("NCP" later came to be used as the name for the protocol, but it originally meant the program within the operating system that managed connections. The protocol itself was known blandly only as the host-host protocol.)
  6. ↑ Mail Transfer Protocol. doi: 10.17487/RFC0772 . RFC 772 . Retrieved 5 August 2022.
  7. ↑ Hafner & Lyon 1996 , pp.  116, 149
  8. ↑ Interface Message Processor: Specifications for the Interconnection of a Host and an IMP (PDF) (Report). Bolt Beranek and Newman (BBN). Report No. 1822.
  9. ↑ Meeting of the ARPA Computer Network Working Group at UCLA, November 16, 1967
  10. ↑ RFC 6529. doi: 10.17487/RFC6529 .
  11. ↑ RFC   53
  12. ↑ Heart, F.; McKenzie, A.; McQuillian, J.; Walden, D. (January 4, 1978). Arpanet Completion Report (PDF) (Technical report). Burlington, MA: Bolt, Beranek and Newman. p. III-63.
  13. ↑ Crocker, S.; Carr, S.; Cerf, V. (12 February 1970). New HOST-HOST Protocol. p. 4. doi: 10.17487/RFC0033 . RFC 33. Processes within a HOST communicate with the network through a Network Control Program (NCP). - Earliest RFC reference to NCP acronym. Explicit definition of NCP as Network Control Program.
  14. ↑ Crocker, Stephen. "NCP -- Network Control Program". Living Internet.com. Retrieved 22 February 2022.
  15. ↑ UGC -NET/JRF/SET PTP & Guide Teaching and Research Aptitude. High Definition Books. p. 319.
  16. ↑ "NCP, Network Control Program". LivingInternet. Retrieved 2022-12-26.
  17. ↑ UGC -NET/JRF/SET PTP & Guide Teaching and Research Aptitude. High Definition Books. p. 319.
  18. ↑ Hauben, Ronda (2004). "The Internet: On its International Origins and Collaborative Vision". Amateur Computerist. 12 (2). Retrieved May 29, 2009.
  19. ↑ Reynolds, J.; Postel, J. (1987). The Request For Comments Reference Guide. doi: 10.17487/RFC1000 . RFC 1000.
  20. ↑ New HOST-HOST Protocol. doi: 10.17487/RFC0033 . RFC 33 . Retrieved 2022-08-04.
  21. ↑ Postel, J. (November 1981). "The General Plan". NCP/TCP transition plan. IETF. p. 2. doi: 10.17487/RFC0801 . RFC 801 . Retrieved February 1, 2011.
  22. ↑ Danesi, Marcel (2013). Encyclopedia of Media and Communication. University of Toronto Press. ISBN   9781442695535.
  23. ↑ "Marking the birth of the modern-day Internet". Google Official Blog. 1 January 2013. Retrieved 19 September 2015.
  24. ↑ "Internet celebrates 40th birthday: but what date should we be marking?". The Telegraph. 2 September 2009. Retrieved 19 September 2015.

Sources

Further reading

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