SNA Terms and Concepts

Basic APPN Concepts

When setting up a workstation, you must define the CP name. The CP is also an LU that can support user sessions, and it can be the only LU defined in your workstation, if you so choose.

Locating Resources

To support communication between TPs, SNAplus2 first establishes a session between the logical units that control those TPs. APPN enables the CP on a node to locate LUs throughout the APPN network without requiring that the node have any configuration information for the remote LU. The APPN function that dynamically locates LUs in the network is called directory services. Once a resource has been located, a route for the session is calculated through the APPN network.

Resource Names

Each node has a unique name consisting of two parts: a network name and a control point name. Together they constitute a fully qualified CP name. This name identifies each node to all other nodes in the network. Similarly, each logical unit is identified by a fully qualified LU name, consisting of a network name and LU name.

Directory Services

Each APPN node maintains a directory of network resources. Directory services is the component of the node CP that manages the local directory database and, in a network node, searches for network resources throughout an APPN network.

When the node is initialized, it includes the following information:

•Node type (APPN network node, APPN end node, or LEN node)

•Network ID of node

•CP name of node

Each node directory maintains entries for resources (LUs and CPs), including each resource's fully qualified name, type, and registration status. The specific resources stored in each local directory depend on the node type:

•A LEN node maintains a directory that includes its own LUs. It must also be configured with directory entries for all of its possible partner LUs. LUs in the APPN network with which the LEN node may want to establish sessions must be defined to the LEN node as if they

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Chapter 1