IBM 3745

The IBM 3745 is the latest and last of a 37xx family of communications controllers for the IBM mainframe environment. As of late 2007 there were an estimated 20,000+ of the larger 3745 models still in active production status. The 3745 and associated 3746 models are heavily used within financial, insurance and retail industries as well as within government agencies globally. IBM announced in late 2002 that it would no longer manufacture new 3745s, but IBM continues to support the hardware by providing worldwide maintenance service, by providing microcode releases and by supporting the associated software including NCP (Network Control Program) and the virtual telecommunications access method (VTAM). A variety of smaller companies provide a range of 3745 products and services, allowing continued use of the 3745/3746 controllers. IBM has not announced a global end-of-service date, although IBM Japan has announced an end of service date of December 31, 2010. [http://www.networking.ibm.com/nhd/webnav.nsf/pages/375:375prod.html]

The latest and most commonly used models of the 3745 are the 3745-31A single CCU and 3745-61A dual CCU models. These are usually operated in conjunction with the 3746-900 expansion unit (aka 900 frame). The 900 frame provides multiple T1, token ring, V.35 and V.24 attachments on the front end, and connects on the back end to the mainframe host with multiple ESCON serial fiber optic channels. An operator and service interface to the 3745 and 900 frame is provided by an IBM Service Processor which operates under the control of the IBM OS/2 operating system and proprietary code.

Replacements

There is no direct hardware replacement for the IBM 3745 providing all of the 3745/3746 interfaces. However, IBM offers a software emulation product that provides a subset of 3745/3746 function, IBM's [http://www.ibm.com/software/network/ccl/ Communications Controller for Linux on System z] . CCL is a software emulation that runs on the mainframe under Linux. The NCP (Network Control Program) licensed for use in the 3745/3746 continues to be licensed for use with CCL. CCL employs the IBM OSA adapter for physical connectivity. Low and medium speed lines must be supported through router ports. Alternatively, in many cases it is possible to migrate away from networking protocols supported by the 3745 and CCL, relying solely on the SNA and TCP/IP protocol support provided by [http://www.ibm.com/software/network/commserver/os390/ Communications Server for z/OS] .