SNA Terms and Concepts

Basic APPN Concepts

only a single link to an adjacent network node server and a link to the connection network, instead of configuring every possible link to every node.

To use the connection network feature, an APPN network must meet the following conditions:

•The nodes in the APPN network must be linked using switched media such as token ring or Ethernet (see “DLCs”).

•All of the links in the APPN network must use the same media.

•The APPN network that contains the connection network must be fully connected. In a fully connected network, each node has at least one link that supports CP-CP sessions to an adjacent node.

In a connection network, the SATF serves as a virtual routing node (VRN) that attaches directly to each node in the connection network. The name of the connection network serves as the name of the control point for the VRN. The VRN supports the direct routing of session data between any two nodes in the connection network, but it does not establish CP-CP sessions with other nodes and it does not generate TDUs. Each node in the connection network requires only a link to its network node server.

The link definitions needed when using a connection network are shown in Figure 1-11, “Definitions Needed for Direct Links Using a Virtual Node.” By using a virtual node, the connection network supports direct links between Node EN1 and every other node in the APPN network, yet it requires only two link definitions.

Chapter 1

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