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The IBM 374× Communication Controllers, and the NCP (network control program) software that runs on them, have been at the center of the IBM SNA (Systems Network Architecture) for many years. However, the 374× hardware is no longer being produced. In order to continue to offer IBM customers various functions provided by the NCP product, IBM has developed a Communication Controller for Linux® (CCL) for the IBM System z™. CCL is a software program that emulates the 374x hardware, enabling the NCP to function in Linux. IBM customers now have the ability to migrate their NCP product to a Linux partition on System z. The current NCP product, running on an IBM 374x Communication Controller, supports both host channel and network attachment. The channel protocol used for the host-channel support is referred to as channel data link control (CDLC). In order to provide the System z9™ host operating systems with the ability to attach to the new CCL NCP over a channel interface, a new channel adapter is required. The new innovative Open Systems Adapter for NCP (OSN) channel support provided by the OSA-Express2 allows various operating systems on the same System z9 to attach “internally” to the CCL without using any external network or channel fabric.
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