TN Server

3270 emulation programs that communicate over TCP/IP (rather than over an SNA network) are referred to as TN3270 programs (Telnet 3270 emulation programs).

TN3270 programs can also include support for TN3270E (Telnet 3270 standard extensions). TN3270E supports 3270 device emulation (including both terminals and printers) using Telnet. It enables a Telnet client to select a particular device (by specifying the LU name or the name of an LU pool), and provides enhanced support for various functions, including the ATTN and SYSREQ keys and SNA response handling.

Note: This guide uses the term TN3270 for information that applies equally to the TN3270, TN3287, and TN3270E protocols.

CS/AIX TN server provides access to 3270 host computers for TN3270 users on other computers. TN server enables TN3270 users to share a host connection with CS/AIX or with other TN3270 users, instead of requiring a direct link. TN server also enables TN3270 users to access hosts that are not running TCP/IP.

The CS/AIX TN server function is illustrated in Figure 1.

The CS/AIX TN server feature provides an association between a TN3270 user and CS/AIX 3270 LU. All data from the TN3270 user is routed to the LU. This means that the configuration for both the host and the TN3270 user is as though they were connected directly; neither needs to be aware that data is being routed through TN server.

CS/AIX TN server supports all TN3270 client emulation programs that correctly implement the protocols defined in IETF RFCs 1123, 1576, 1646, 1647, and 2355.