Telnet Suppress Go Ahead Option

　　Network Working Group J. Postel

　　Request for Comments: 858 J. Reynolds

　　ISI

　　Obsoletes: NIC 15392 May 1983

　　TELNETSUPPRESS 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.

　　RFC858May 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.