Network Working Group J. Penner
Request for Comments: 1576 DCA, Inc.
Category: Informational January 1994
TN3270 Current Practices
Status of this Memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
Abstract
This document describes the existing implementation of transferring
3270 display terminal data using currently available telnet
capabilities. The name traditionally associated with this
implementation is TN3270.
Information is provided to aid in the implementation of TN3270
servers as well as client terminal emulators.
The following areas pertaining to TN3270 implementations are covered
in this document:
1. the telnet options negotiated to transition from a NVT ASCII
state to a TN3270 state ready to process incoming 3270 data
stream commands
2. the method for sending and receiving 3270 data
3. the method of handling some special keys known as SYSREQ and
ATTN using current available telnet commands
4. the events that will transition a TN3270 session back to an NVT
session
Table of Contents
1. Motivation . . . . . . . . . . . . . . . . . . . 2
2. Background . . . . . . . . . . . . . . . . . . . 2
3. Telnet Options and Commands Used . . . . . . . . 4
4. Connection Negotiation . . . . . . . . . . . . . 4
4.1 3270 Regime Option . . . . . . . . . . . . . . . 6
4.2 Suppress Go Ahead Option . . . . . . . . . . . . 6
4.3 Echo Option . . . . . . . . . . . . . . . . . . . 6
4.4 Timing Mark Option . . . . . . . . . . . . . . . 7
TN3270 Enhancements Working Group