SNA 7-layer model maps closely to OSI RM. The SNA and OSI layers are not identical and may not be inter-operable unless some form of gateway is provided.
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Physical - SNA does not define this layer (runs over Ethernet, FDDI, FR, X.25)
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Data Link Control - defines several IBM protocols including SDLC (Synchronous DLC), Token Ring Network, X.25
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Path Control - performs routing, and segmentation and re-assembly (SAR)
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Transmission Control - provides reliable end-to-end connection; encryption
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Data Flow Control - manages request and response processing
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Presentation services - coordinates resource sharing, converts data formats
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Transaction services - provide application services (management and distributed processing)
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