SNA Terms and Concepts
Basic SNA Concepts
Each node manages its end of the network communication paths, and uses SNA protocols to communicate with the node at the other end of each path.
Because subarea networks and peer networks define the relationships among nodes differently, they also use different terms for node types (to describe the roles that nodes play in the network).
Node Types in a Subarea NetworkSNA subarea networks support the following node types:
• Subarea nodes control communication and network resources for all attached nodes. SNA classifies subarea nodes according to their capabilities and the amount of control they have over other nodes:
• Type 5 nodes provide SNA functions that control network resources, support transaction programs, support network operators, and provide
• Type 4 nodes provide SNA functions that route and control the flow of data in a part of the network. Because these functions are often provided by communication controllers, type 4 nodes are also known as communication controller nodes.
• Peripheral nodes serve subordinate roles in subarea networks. For example, a peripheral node can support 3270 emulation or dependent LU 6.2 communication. Peripheral nodes are devices such as distributed processors, cluster controllers, or workstations; they are also classified into type 2.0 and type 2.1 nodes:
• Type 2.0 nodes are always controlled by a type 4 or 5 node. They
| cannot establish communication with other nodes without the |
| participation of a type 4 or 5 node. Type 2.0 nodes are referred to |
| as dependent nodes. |
| • Type 2.1 nodes can act as dependent nodes, but they can also |
| communicate directly with other type 2.1 nodes. |
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NOTE | |
| 2.0 nodes. |
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