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Network Working Group C. Hedrick Request for Comments: 1079 Rutgers University

                                                         December 1988

                    Telnet Terminal Speed Option

Status of This Memo

 This RFC specifies a standard for the Internet community.  Hosts on
 the Internet that exchange terminal speed information within the
 Telnet protocol are expected to adopt and implement this standard.
 Distribution of this memo is unlimited.

 This standard is modelled on RFC 930 [1], the telnet terminal type
 option.  Much of the text of this document is copied from that RFC.

Motivation

 Most operating systems have provisions to keep track of the speed
 (bit rate) of directly attached terminals and modems.  This
 information is used to control various timing-dependent display
 processes, e.g., the number of padding characters used for delay.
 Some software also has user interfaces that are tuned differently for
 fast and slow terminals.  The purpose of this option is to provide
 similar information for telnet connections.

1. Command Name and Code

    TERMINAL-SPEED

    Code = 32

2. Command Meanings

    IAC WILL TERMINAL-SPEED

       Sender is willing to send terminal speed information in a
       subsequent sub-negotiation.

    IAC WON'T TERMINAL-SPEED

       Sender refuses to send terminal speed information.

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    IAC DO TERMINAL-SPEED

       Sender is willing to receive terminal speed information in a
       subsequent sub-negotiation.

    IAC DON'T TERMINAL-SPEED

       Sender refuses to accept terminal speed information.

    IAC SB TERMINAL-SPEED SEND IAC SE

       Sender requests receiver to transmit his (the receiver's)
       terminal speed. The code for SEND is 1. (See below.)

    IAC SB TERMINAL-SPEED IS ... IAC SE

       Sender is stating his terminal speed. The code for IS is 0.
       (See below.)

3. Default

    WON'T TERMINAL-SPEED

       Terminal speed information will not be exchanged.

    DON'T TERMINAL-SPEED

       Terminal speed information will not be exchanged.

4. Description of the Option

 WILL and DO are used only to obtain and grant permission for future
 discussion. The actual exchange of status information occurs within
 option subcommands (IAC SB TERMINAL-SPEED...).

 Once the two hosts have exchanged a WILL and a DO, the sender of the
 DO TERMINAL-SPEED is free to request speed information.  Only the
 sender of the DO may send requests (IAC SB TERMINAL-SPEED SEND IAC
 SE) and only the sender of the WILL may transmit actual speed
 information (within an IAC SB TERMINAL-SPEED IS ... IAC SE command).
 Terminal speed information may not be sent spontaneously, but only in
 response to a request.

 The terminal speed information is an NVT ASCII string.  This string
 contains the decimal representation of the transmit and receive
 speeds of the terminal, separated by a comma, e.g.,

       9600,100

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 No leading zeros may be included.  No extraneous characters such as
 spaces may be included.

    The following is an example of use of the option:

       Host1: IAC DO TERMINAL-SPEED

       Host2: IAC WILL TERMINAL-SPEED

    (Host1 is now free to request status information at any time.)

       Host1: IAC SB TERMINAL-SPEED SEND IAC SE

       Host2: IAC SB TERMINAL-SPEED IS "1200,1200" IAC SE

    (This command is 15 octets.)

5. Implementation Suggestions

 Many systems allow only certain discrete terminal speeds.  In such
 cases it is possible that a speed may be received that does not match
 one of the allowed values.  We suggest that you pick the nearest
 speed that is allowed, rounding in a "safe" direction.  Safety will
 depend upon the use of the speed information.  If it is being used
 for padding, it is best to round up, since too much padding is better
 than too little.

Reference

 [1]  Solomon, M., and Wimmers, E., "Telnet Terminal Type Option",
      RFC 930, January, 1985

[AAuthor's Address:

 Charles Hedrick
 Rutgers University
 Center for Computer and Information Services
 Hill Center, Busch Campus
 P.O. Box 879
 Piscataway, NJ 08855-0879

 Phone: (201) 932-3088

 Email: HEDRICK@ARAMIS.RUTGERS.EDU

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