Systems Network Architecture

Systems Network Architecture

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Systems Network Architecture (SNA) is a networking architecture developed by IBM in the 1970s. It defines a set of protocols and standards for connecting and communicating between IBM mainframe systems and peripheral devices. Here are key points about SNA:

  1. Architecture: SNA is designed to facilitate communication and data exchange within a network of IBM mainframe systems, terminals, and other devices. It provides a hierarchical structure with various layers and components.
  2. Logical Structure: SNA organizes network components into logical entities called Logical Units (LUs). Each LU represents a specific device or application within the network and is identified by a unique address.
  3. Data Flow: SNA employs a hierarchical data flow model, where data is exchanged between nodes in the network. Data flows from the source LU to intermediate nodes called Intermediate Session Control Units (ISCUs), and finally to the destination LU.
  4. Protocols: SNA includes a set of protocols for various aspects of network communication, such as session establishment, data transfer, and error recovery. Notable protocols in SNA include Advanced Program-to-Program Communication (APPC) and LU6.2.
  5. Data Formats: SNA defines specific data formats for exchanging information between network entities. For example, the Systems Network Architecture Data Format (SNADF) is used for transmitting data within SNA networks.
  6. Connectivity: SNA supports a variety of network connectivity options, including dedicated leased lines, dial-up connections, and more modern networking technologies such as TCP/IP. SNA can operate over different physical media, such as Ethernet, Token Ring, or X.25.
  7. Security and Management: SNA provides mechanisms for authentication, authorization, and secure data transmission within the network. It also includes management features for monitoring and controlling network resources.
  8. Legacy Technology: SNA was widely used in IBM mainframe environments during the 1980s and 1990s. While its usage has decreased with the rise of modern networking technologies, there are still organizations that maintain legacy SNA networks and applications.

It’s important to note that SNA is a proprietary networking architecture specific to IBM systems. It played a significant role in the history of mainframe computing and provided reliable and secure networking capabilities for IBM customers.

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