RFC 55 - A Prototypical Implementation of the NCP

• Status: Unknown
• Published: 19 June 1970
• Stream: Legacy
• Errata: No Errata

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Document Information

• RFC Number: 55
• Title: A Prototypical Implementation of the NCP
• Authors: J. Newkirk (Harvard), M. Kraley (Harvard), J. Postel (UCLA), S. Crocker (UCLA)
• Date: June 1970
• Category: Unknown

Abstract

This memo describes a prototypical implementation of the Network Control Program (NCP) for the ARPA Network. It postulates a time-sharing environment with processes, ports and local sockets, and defines a set of system calls (CONNECT, LISTEN, ACCEPT, TRANSMIT, INT, STATUS and CLOSE) together with their condition codes. The authors then outline the gross structure of the NCP - five component programs, associative tables, queues and buffers - describe the rendezvous, input link, output link, port, output control command, output request, host live and link assignment tables, narrate the opening, flow control and closing phases of a connection, present a ten-state connection state machine, and give algorithms for the input interpreter (NOP, RFC, CLS, ERR, ECO, ERP, INR/INS, ALL and Data-RFNM) and for the system call interpreter. The document is offered as an example, not as a model.

Table of Contents

• Introduction
• II. Environment
• III. System Calls
  • CONNECT (P, AEN, FS, CR)
  • LISTEN (P, AEN, CR)
  • ACCEPT (P, CR)
  • TRANSMIT (P, BUFF, BITSRQST, BITSACC, CR)
  • INT (P, CR)
  • STATUS (P, RTAB, CR)
  • CLOSE (P, CR)
• IV. The NCP - Gross Structure
  • The Component Programs (see Fig. 4.1)
  • 1. The Input Handler
  • 2. The Output Handler
  • 3. The Input Interpreter
  • 4. The Output Scheduler
  • 5. The System Call Interpreter
• V. Tables in the NCP
  • 1. The Rendezvous Table
  • 2. The Input Link Table
  • 3. The Output Link Table
  • 4. The Port Table
  • 5. The Output Control Command Table
  • 6. The Output Request Queue
  • 7. The Host Live Table
  • 8. The Link Assignment Table
• VI. Informal Description of Network Operations
  • A. Opening
    • 1. Pending Call Queues
  • B. Flow Control
  • C. Closing
    • 1. Aborting
    • 2. Refusing
    • 3. Terminating by the Sender
    • 4. Terminating by the Receiver
• VII. Connection Status
  • (0) CLOSED
  • (1) PENDING CALL
  • (2) LISTENING
  • (3) RFC-RCVD
  • (4) ABORT
  • (5) RFC-SENT
  • (6) OPEN
  • (7) CLS-WAIT
  • (8) DATA-WAIT
  • (9) RFNM-WAIT
• VIII. Algorithms for the Input Interpreter
  • NOP
  • RFC (RTS or STR)
  • CLS
  • ERR
  • ECO
  • ERP
  • INR, INS
  • ALL
  • Data-RFNM
• IX. Algorithms for the System Call Interpreter
  • CONNECT
  • LISTEN
  • ACCEPT
  • CLOSE

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Related Resources

• Official RFC: RFC 55
• DataTracker: RFC 55 Info
• Errata: RFC Editor Errata