Browse Prior Art Database

Host Software (RFC0001) Disclosure Number: IPCOM000001801D
Original Publication Date: 1969-Apr-01
Included in the Prior Art Database: 2019-Feb-11
Document File: 11 page(s) / 13K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

S. Crocker: AUTHOR

Related Documents

10.17487/RFC0001: DOI

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 18% of the total text.

Network Working Group Steve Crocker Request for Comments: 1 UCLA 7 April 1969

Title: Host Software Author: Steve Crocker Installation: UCLA Date: 7 April 1969 Network Working Group Request for Comment: 1



I. A Summary of the IMP Software



IMP Transmission and Error Checking

Open Questions on the IMP Software

II. Some Requirements Upon the Host-to-Host Software

Simple Use

Deep Use

Error Checking

III. The Host Software

Establishment of a Connection

High Volume Transmission

A Summary of Primitives

Error Checking

Closer Interaction

Open Questions

Crocker [Page 1]

RFC 1 Host Software 7 April 1969

IV. Initial Experiments

Experiment One

Experiment Two


The software for the ARPA Network exists partly in the IMPs and partly in the respective HOSTs. BB&N has specified the software of the IMPs and it is the responsibility of the HOST groups to agree on HOST software.

During the summer of 1968, representatives from the initial four sites met several times to discuss the HOST software and initial experiments on the network. There emerged from these meetings a working group of three, Steve Carr from Utah, Jeff Rulifson from SRI, and Steve Crocker of UCLA, who met during the fall and winter. The most recent meeting was in the last week of March in Utah. Also present was Bill Duvall of SRI who has recently started working with Jeff Rulifson.

Somewhat independently, Gerard DeLoche of UCLA has been working on the HOST-IMP interface.

I present here some of the tentative agreements reached and some of the open questions encountered. Very little of what is here is firm and reactions are expected.

I. A Summary of the IMP Software


Information is transmitted from HOST to HOST in bundles called messages. A message is any stream of not more than 8080 bits, together with its header. The header is 16 bits and contains the following information:

Destination 5 bits Link 8 bits Trace 1 bit Spare 2 bits

The destination is the numerical code for the HOST to which the message should be sent. The trace bit signals the IMPs to record status information about the message and send the information back to the NMC (Network Measurement Center, i.e., UCLA). The spare bits are unused.

Crocker [Page 2]

RFC 1 Host Software 7 April 1969


The link field is a special device used by the IMPs to limit certain kinds of congestion. They function as follows. Between every pair of HOSTs there are 32 logical full-duplex connections over which messages may be passed in either direction. The IMPs place the restriction on these links that no HOST can send two successive messages over the same link before the IMP at the destination has sent back a special message called an RFNM (Request for Next Message). This arrangement limits the congestion one HOST can cause another if the sending HOST is attempting to send too much over one link. We note, however, that since the IMP at the destination does not have enough capacity to handle all 32 link...