RFC858 - Telnet Suppress Go Ahead Option

Network Working Group J. Postel

Request for Comments: 858 J. Reynolds

ISI

Obsoletes: NIC 15392 May 1983

TELNET SUPPRESS GO AHEAD OPTION

This RFCspecifies a standard for the ARPA Internet community. Hosts on

the ARPA Internet are eXPected to adopt and implement this standard.

1. Command Name and Code

SUPPRESS-GO-AHEAD 3

2. Command Meanings

IAC WILL SUPPRESS-GO-AHEAD

The sender of this command requests permission to begin

suppressing transmission of the TELNET GO AHEAD (GA) character

when transmitting data characters, or the sender of this command

confirms it will now begin suppressing transmission of GAs with

transmitted data characters.

IAC WON'T SUPPRESS-GO-AHEAD

The sender of this command demands to begin transmitting, or to

continue transmitting, the GA character when transmitting data

characters.

IAC DO SUPPRESS-GO-AHEAD

The sender of this commannd requests that the sender of data start

suppressing GA when transmitting data, or the sender of this

command confirms that the sender of data is expected to suppress

transmission of GAs.

IAC DON'T SUPPRESSS-GO-AHEAD

The sender of this command demands that the receiver of the

command start or continue transmitting GAs when transmitting data.

3. Default

WON'T SUPPRESS-GO-AHEAD

DON'T SUPPRESS-GO-AHEAD

Go aheads are transmitted.

RFC858 May 1983

4. Motivation for the Option

While the NVT nominally follows a half duplex protocol complete with

a GO AHEAD signal, there is no reason why a full duplex connection

between a full duplex terminal and a host optimized to handle full

duplex terminals should be burdened with the GO AHEAD signal.

Therefore, it is desirable to have a TELNET option with which parties

involved can agree that one or the other or both should suppress

transmission of GO AHEADS.

5. Description of the Option

When the SUPPRESS-GO-AHEAD option is in effect on the connection

between a sender of data and the receiver of the data, the sender

need not transmit GAs.

It seems probable that the parties to the TELNET connection will

suppress GO AHEAD in both directions of the TELNET connection if GO

AHEAD is suppressed at all; but, nonetheless, it must be suppressed

in both directions independently.

With the SUPPRESS-GO-AHEAD option in effect, the IAC GA command

should be treated as a NOP if received, although IAC GA should not

normally be sent in this mode.

6. Implementation Considerations

As the SUPRESS-GO-AHEAD option is sort of the opposite of a line at a

time mode, the sender of data which is suppressing GO AHEADs should

attempt to actually transmit characters as soon as possible (i.e.,

with minimal buffering) consistent with any other agreements which

are in effect.

In many TELNET implementations it will be desirable to couple the

SUPPRESS-GO-AHEAD option to the echo option so that when the echo

option is in effect, the SUPPRESS-GO-AHEAD option is in effect

simultaneously: both of these options will normally have to be in

effect simultaneously to effect what is commonly understood to be

character at a time echoing by the remote computer.