Browse Prior Art Database

Telnet remote flow control option (RFC1080)

IP.com Disclosure Number: IPCOM000001889D
Original Publication Date: 1988-Nov-01
Included in the Prior Art Database: 2000-Sep-12
Document File: 3 page(s) / 6K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

C.L. Hedrick: AUTHOR

Abstract

Status of This Memo

This text was extracted from a ASCII document.
This is the abbreviated version, containing approximately 46% of the total text.

Network Working Group C. Hedrick

Request for Comments: 1080 Rutgers University

November 1988

Telnet Remote Flow Control Option

Status of This Memo

This RFC specifies a standard for the Internet community. Hosts on

the Internet that do remote flow control within the Telnet protocol

are expected to adopt and implement this standard. Distribution of

this memo is unlimited.

Motivation

This memo describes a method of remotely toggling flow control

between a user telnet process and the attached terminal. Only flow

control of data being transmitted from the telnet process to the

terminal is considered. Many systems will also allow flow control of

data from the terminal to the telnet process. However there is

seldom need to change this behavior repeatedly during the session.

There are two common ways of doing flow control: hardware and

software. Hardware flow control uses signals on wires dedicated for

this purpose. Software flow control uses one or two specific

characters sent along the same path as normal input data. Most

commonly, XOFF (control-S) and XON (control-Q) are used to stop and

start output, respectively. The option described herein is useful

primarily where software flow control is being used. (Since hardware

flow control does not preempt any characters, there is normally no

need to disable it.)

The primary difficulty with software flow control is that it preempts

one or two characters. Host software often requires the user to be

able to input every possible ASCII character. (Certain editors are

notorious for having XOFF and XON as commonly-used commands.) For

this reason, operating systems often allow programs to disable flow

control. While it is disabled, the characters that normally signal

flow control may be read as normal input. In a telnet environment,

flow control is normally done by the user telnet process, not by the

host computer. Thus this RFC defines a way to propagate flow control

status from the host computer to the user telnet process.

1. Command Name and Code

TOGGLE-FLOW-CONTROL

Code = 33

2. Command Meanings

IAC WILL TOGGLE-FLOW-CONTROL

Sender is willing to enable and disable flow control upon

command.

IAC WON'T TOGGLE-FLOW-CONTROL

Sender refuses to enable and disable flow control. Nothing is

implied about whether sender does or does not use flow control.

It is simply unwilling to enable and disable it using ...