IBM is tipped to come out with a new generation of front end processors to complement the 372X successors to the 3705, but, more importantly, to support a major evolution of Systems Network Architecture into a fully federal networking system – and to be as much at home front-ending the Silverlake successor to the 38 and 36 as it is supporting the 3090s, 4381s and 9370s. Le Monde Informatique looks for two models, a powerful high-end 2725, and an entry-level 2720, and expects that as well as SNA, they will support X25 packet switching and the Token Ring, and perhaps other communications protocols as well. The 2720 is expected to come with 6Mb and 64 ports, and is not initially expected to support X25, but the 2725 is expected to be capable of standing up to NCR-Comten’s 5660, which supports up to 1,056 ports and can handle T-1 lines, against only 400 ports for IBM’s present flagship, the 3725. Needless to say, the new processors will need a new release of the Network Control Program, which will enable them to look like a PU2.1 as well as LU6.2. The key difference between SNA and the Open Systems Interconnection model is that in SNA, part of the communication function – the VTAM Virtual Telecommunications Access Method – resides on the host, and gets mixed up with the applications, where there is a clean break in OSI. It is now thought possible that in the new release of SNA to accompany the new front-end processors, IBM will move VTAM – or parts of it – out of the host, to create the same clean break as in Open Systems Interconnection, in particular shifting message routing out of the host. But a word of warning: launch of the 3725 front-end successor to the 3705 was regularly forecast as imminent for a full six years before it was announced.
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