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A Simplified NCP Protocol (RFC0060)

IP.com Disclosure Number: IPCOM000003674D
Original Publication Date: 1970-Jul-01
Included in the Prior Art Database: 2015-Feb-13
Document File: 16 page(s) / 19K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

R. Kalin: AUTHOR

Abstract

This RFC defines a new NCP protocol that is simple enough to be implemented on a very small computer, yet can be extended for efficient operation on large timesharing machines. Because worst case storage requirements can be predicted, a conservative implementation can be freed of complicated resource allocation and storage control procedures. A general error recovery procedure is also defined.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 15% of the total text.

Network Working Group                                           R. Kalin Request for Comments: 60                                             MIT                                                             13 July 1970

                        A Simplified NCP Protocol

Abstract

   This RFC defines a new NCP protocol that is simple enough to be    implemented on a very small computer, yet can be extended for    efficient operation on large timesharing machines. Because worst case    storage requirements can be predicted, a conservative implementation    can be freed of complicated resource allocation and storage control    procedures. A general error recovery procedure is also defined.

Overview and Rational

   The central premise of this proposal is an insistence that all user-    to-user connections be bi-directional. For those familiar with    communication theory, this appears most reasonable. All communication    requires a cyclical flow of information. To deny a simple association    between a message and its reply makes protocol unnecessarily    complicated and turns simple mechanisms of flow control into    nightmares.

   It is proposed that a bi-directional connection, or duplex link, be    identified by a pair of socket numbers, one for each end. This is    half the number presently required. Associated with the connection    are some number of "crates" or message containers. These crates    travel back and forth over the link carrying network messages from    one side to the other. Buffers are allocated at each end of the link    to hold crates and the messages that they carry. Worst case buffer    requirements are equal to the number of crates in circulation, or the    "capacity" of the link.

Details

   A message buffer has four states which follow one another cyclically.    They are:

   1) empty,

   2) filled with a message-laden crate to be unloaded,

   3) filled with an empty crate, and

   4) filled with a message-laden crate to be sent.

Kalin                                                           [Page 1]
 RFC 60                  A Simplified NCP Protocol           13 July 1970

    Normally state transitions correspond to message arrival, message    removal, message insertion and message transmission.

   For a process to be an NCP it must:

   1) be able to make initial contact with foreign hosts via the control    link and, if necessary, delete user-to-user links left over from the    previous system incarnation.

   2) be able to create user-to-user links.

   3) be able to interface users with these links.

   4) be able to delete user-to-user links.

   The first of the four func...