Networking on z/OS
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Systems Network Architecture - basics and implementation

Networking on z/OS

An SNA network implements the IBM proprietary networking architecture. Subarea networking carries out a hierarchical network paradigm. The information about the network resources and the definitions are stored in the mainframe that is located at the top of the hierarchy. The hierarchical structure of the network follows the organizational structure of many enterprises and that's one of the reasons that SNA was accepted and implemented by many enterprises.

In an SNA subarea network, the routes between subarea nodes and almost all the resources are pre-defined.

In TCP/IP, the unit that is transferred through the network is called a packet. A packet includes the data (payload) and the IP and TCP headers used to route the packet and manage the TCP session. In SNA the unit that flows in the network is called a path information unit (PIU). It carries the data, the SNA headers, the transmission header (TH), and request header (RH).

SNA in general has robust data flow control that permits constant flow of data to and from the network and prevents congestion in network resources.

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