Telnet end of record option (original) (raw)

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PROPOSED STANDARD

Network Working Group J. Postel Request for Comments: 885 ISI December 1983

                  TELNET END OF RECORD OPTION

This RFC specifies a standard for the ARPA Internet community. Hosts on the ARPA Internet that need to mark record boundaries within Telnet protocol data are expected to adopt and implement this standard.

1. Command Name and Code

END-OF-RECORD 25

2. Command Meanings

IAC WILL END-OF-RECORD

  The sender of this command requests permission to begin
  transmission of the Telnet END-OF-RECORD (EOR) code when
  transmitting data characters, or the sender of this command
  confirms it will now begin transmission of EORs with transmitted
  data characters.

IAC WON'T END-OF-RECORD

  The sender of this command demands to stop transmitting, or to
  refuses to begin transmitting, the EOR code when transmitting data
  characters.

IAC DO END-OF-RECORD

  The sender of this command requests that the sender of data start
  transmitting the EOR code when transmitting data, or the sender of
  this command confirms that the sender of data is expected to
  transmit EORs.

IAC DON'T END-OF-RECORD

  The sender of this command demands that the receiver of the
  command stop or not start transmitting EORs when transmitting
  data.

3. Default

WON'T END-OF-RECORD

DON'T END-OF-RECORD

END-OF-RECORD is not transmitted.

Postel [Page 1]

RFC 885 December 1983

4. Motivation for the Option

Many interactive systems use one (or more) of the normal data characters to indicate the end of an effective unit of data (i.e., a record), for example, carriage-return (or line-feed, or escape). Some systems, however, have some special means of indicating the end of an effective data unit, for example, a special key. This Telnet option provides a means of communicating the end of data unit in a standard way.

5. Description of the Option

When the END-OF-RECORD option is in effect on the connection between a sender of data and the receiver of the data, the sender transmits EORs.

It seems probable that the parties to the Telnet connection will transmit EORs in both directions of the Telnet connection if EORs are used at all; however, the use of EORs must be negotiated independently for each direction.

When the END-OF-RECORD option is not in effect, the IAC EOR command should be treated as a NOP if received, although IAC EOR should not normally be sent in this mode.

6. Implementation Considerations

As the EOR code indicates the end of an effective data unit, Telnet should attempt to send the data up to and including the EOR code together to promote communication efficiency.

The end of record is indicated by the IAC EOR 2-octet sequence. The code for EOR is 239 (decimal).

Postel [Page 2]