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RFC 0858

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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