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