WASHINGTON, D.C. - Mainframe professionals attending the recent SHARE conference got a close look at some of the streamlined new technologies designed to replace their cumbersome, and now unsupported, IBM 3174 control units.
IBM no longer produces or supports the 3174 control unit, a large, physical box that serves as an interface between 3270, or "green screen," workstations and the mainframe itself.
The 3174 is responsible for tasks not directly related to the mainframe's processor, such has keystroke management and screen clearing. The unit connects to green screen consoles via coaxial cable, token ring and serial connectors, and sometimes Ethernet. The connection to the mainframe is generally through parallel channel cables, or very rarely, ESCON cables.
While the 3174 unit is still widely used, analysts and users point out that more and more data centers are beginning to seek alternatives. Most of the replacements available today, say the analysts, employ channel-attached personal computers and network adapters to emulate the 3174. This allows users to say 'goodbye' to the space-inefficient 3174 boxes and the costly coaxial cable.
"The main consideration is that the 3174 is getting old and it occupies a lot of space," said Tom Sipusic, a senior systems programmer at Georgetown University. Sipusic has been assigned the task of shopping around for replacements for the school's 3174 unit. "We'd like to get some of that space back."
"Now that people are finally installing enterprise networks, they're trying to eliminate running coax all over the place," said David Boyes, president and founder of Sine Nomine Associates, a mainframe consulting firm. "For example, one company I worked with took out a little over twenty-five miles of coax by replacing their 3174."
IBM's replacement for the 3174 is the 2074, which like most third-party offerings uses a channel-attached PC. Boyes said the nice thing about the 2074 and similar products is that they can be partitioned. In the heyday of the 3174, users employing a logical partition (LPAR) configuration needed a terminal and a 3174 for each LPAR, he said. A single 2074 can be connected to multiple LPARs, reducing the need for boxes and cable.
Virgil Paul Presta, director of sales and marketing for I/O concepts, another company that was on hand at SHARE marketing its 3174 alternatives, said his company offers three separate replacement programs.
For people who simply want to replace their 3174 and aren't interested in console sharing, there is I/O Concepts' ESCON Gateway, Presta said. The ESCON Gateway can reside on standalone platforms such as Windows or Sun Unix and requires no 3174 or 3270 emulation software, he said.
I/O Concepts' middle of the road product is the Console Consolidation System (CCS). Presta said CCS integrates with ESCON gateway products from other companies like IBM and Visara, and it provides session management capabilities and secure shell connections.
The high-end 3174 replacement from I/O concepts, CCS SmartClient, offers a Java based event and automation engine and can facilitate mainframe e-mail and paging notification based on mainframe console data.
Boyes said the beauty the new methods for interfacing with the mainframe is that they present the same channel interface protocols as the 3174.
"From the mainframe side, it looks like you've got a 3174 and a bunch of dumb terminals," Boyes said. "On the other side, you've got an emulated TN3270 server, you're connecting through an IP network, and your applications can't tell the difference."