5250 Telnet interface
RFC 1205

Document Type RFC - Informational (February 1991; No errata)
Updated by RFC 2877
Last updated 2013-03-02
Stream Legacy
Formats plain text pdf html bibtex
Stream Legacy state (None)
Consensus Boilerplate Unknown
RFC Editor Note (None)
IESG IESG state RFC 1205 (Informational)
Telechat date
Responsible AD (None)
Send notices to (None)
Network Working Group                                     P. Chmielewski
Request for Comments: 1205                               IBM Corporation
                                                           February 1991

                         5250 Telnet Interface

Status of this Memo

   This RFC is being distributed in order to document the interface to
   the IBM 5250 Telnet implementation.  This information is being
   provided for hosts on the Internet that want to support the 5250 work
   station data stream within the Telnet protocol.  This memo provides
   information for the Internet community.  It does not specify any
   standard.  Distribution of this memo is unlimited.

1.  Introduction

   This RFC describes the interface to the IBM 5250 Telnet
   implementation.  The purpose of this memo is to describe the details
   of the interface so that a person wanting to implement a client
   Telnet which emulates an IBM 5250 work station would be able to do
   so.  This memo does not describe all of the 5250 commands, aid codes,
   and other information specific to the 5250 data stream.  That
   information is contained in the IBM 5250 Information Display System,
   Functions Reference Manual, IBM publication number SA21-9247.
   Corrections and additions to this manual are documented in this RFC
   in section 5.

2.  Telnet Options

   No new Telnet options are defined for 5250 mode of operation.
   However, to enable 5250 mode, both the client and server must agree
   to at least support the Binary, End-Of-Record (EOR), and Terminal-
   Type Telnet options.  The complete list of 5250 terminal types is
   maintained in the Assigned Numbers RFC and includes the following:

     IBM-5555-C01   24 x 80 Double-Byte Character Set color display
     IBM-5555-B01   24 x 80 Double-Byte Character Set (DBCS)
     IBM-3477-FC    27 x 132 color display
     IBM-3477-FG    27 x 132 monochrome display
     IBM-3180-2     27 x 132 monochrome display
     IBM-3179-2     24 x 80 color display
     IBM-3196-A1    24 x 80 monochrome display
     IBM-5292-2     24 x 80 color display
     IBM-5291-1     24 x 80 monochrome display
     IBM-5251-11    24 x 80 monochrome display

Chmielewski                                                     [Page 1]
RFC 1205                 5250 Telnet Interface             February 1991

   An example of a typical negotiation process to establish 5250 mode of
   operation is shown below.  In this example, the server initiates the
   negotiation by sending the DO TERMINAL-TYPE request.

    Server: IAC DO TERMINAL-TYPE
    Client: IAC WILL TERMINAL-TYPE
    Server: IAC SB TERMINAL-TYPE SEND IAC SE
    Client: IAC SB TERMINAL-TYPE IS IBM-5251-11 IAC SE
    (The client has specified its terminal-type is an IBM-5251-11)

    Server: IAC DO END-OF-RECORD
    Client: IAC WILL END-OF-RECORD
    Server: IAC WILL END-OF-RECORD
    Client: IAC DO END-OF-RECORD
    (The server and client have both agreed to transmit EORs)

    Server: IAC DO TRANSMIT-BINARY
    Client: IAC WILL TRANSMIT-BINARY
    Server: IAC WILL TRANSMIT-BINARY
    Client: IAC DO TRANSMIT-BINARY
    (The server and client have both agreed to binary transmission)

3.  Data Stream Format

   The actual data stream that is exchanged between the client and
   server is composed of a header followed by the 5250 work station data
   stream.  For information about the 5250 work station data stream
   refer to the IBM 5250 Information Display System, Functions Reference
   Manual (SA21-9247).  The header which prefixes the 5250 data stream
   was originally designed for the 5250 Display Station Pass-Through
   (DSPT) application.  5250 DSPT is an application similar to Telnet
   which runs on the IBM AS/400, System/36, and System/38 over an SNA
   network.  This header is designed to be variable in length and is
   composed of two parts.  The first, fixed part is always 6 octets long
   and has the following format:

      0                   1                   2                   3
      0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |     Logical Record Length     |       Record Type             |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
     |        Reserved               |
     +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Logical Record Length:  16 bits

      This field indicates the length, in octets, of this logical record
      including the header length.  The length is calculated BEFORE

Chmielewski                                                     [Page 2]
RFC 1205                 5250 Telnet Interface             February 1991

      doubling any IAC characters in the data stream.  The length does
      not include the <IAC><EOR> that is appended to the end of the data
      stream to mark the end of this logical record.  The length is
      specified with the most significant octet first.  For example, a
Show full document text