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Network Working Group J. Postel Request for Comments: 858 J. Reynolds

                                                                   ISI

Obsoletes: NIC 15392 May 1983

                  TELNET SUPPRESS GO AHEAD OPTION

This RFC specifies 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.

Postel & Reynolds [Page 1] 

RFC 858 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.

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