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G&R » Products » Host Links » OSI-stacks  


Bull DSA (Distributed Systems Architecture) networks were originally defined in accordance with the Open Systems Interconnection Basic Reference Model; the application, presentation and session layers were defined to run over the standard OSI transport layer (as opposed to IBM's SNA, which runs on a proprietary transport layer).

Host Links includes a line handler for Bull DSA, developed in its entirety by G&R on Open Systems platforms. It implements the application, presentation and session layers of DSA, and will run over any OSI-compliant transport stack.

There is an Internet standard protocol, RFC1006, which defines an OSI-transport interface to TCP/IP (the standard Internet transport layer). G&R have developed an RFC1006 layer, and thus the G&R implementation of DSA can be used to connect over TCP/IP networks to newer Bull systems that have RFC1006 support. We deliver all layers above the standard TCP/IP socket interface of the Open Systems platform on which Host Links is installed.

If the Bull system is still using a legacy OSI-transport based network, then the Host Links platform must have an OSI-stack installed in order to connect using DSA. OSI-stacks are becoming obsolete in competition with TCP/IP, but they are available from the major UNIX providers. Bull AIX, Sun Solaris and HP-UX all have OSI-stacks qualified with Host Links. If you install Host Links on one of these platforms you must obtain the OSI-stack from your supplier.

There are no OSI-stacks available for Linux. DSA connections must be made using RFC1006 over TCP/IP.

For Windows 2003, 2000 and Windows XP there is an OSI-stack available from Marben, and this is qualified, supplied and supported by G&R.

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