9.3 Configuring DLUR

Normally, a dependent LU session requires a direct communications link to the host computer. If many nodes (including a host node) are connected together in an APPN network, some of them may have an indirect connection through another node instead of a direct connection to the host. Without a direct connection, it is not possible to establish dependent LU sessions to the host from LUs in these indirectly connected nodes.

Dependent LU requester (DLUR) is an APPN feature designed to overcome this limitation. DLUR can be configured on an APPN node (such as a node running SNAP-IX). It works in conjunction with dependent LU server (DLUS) at the host, to route sessions from dependent LUs on the DLUR node across the APPN network to the DLUS host.

The route to the host can span multiple nodes and can take advantage of APPN's network management, dynamic resource location, and route calculation facilities. DLUR must be available on the node where the LUs are defined, and DLUS must be available on the host node, but you do not have to enable DLUR on any intermediate nodes in the session route.

If the SNAP-IX DLUR node is a network node, it can also provide passthrough DLUR facilities for dependent LUs on downstream computers connected to the SNAP-IX node. (Only network nodes support this function.) These downstream LUs can use DLUR on the SNAP-IX node to access the host across the network, in the same way that LUs internal to the node do.

The tasks you need to perform to configure DLUR depend on whether the dependent LUs are on the local node or on downstream nodes.

To configure DLUR support on the local node, you must perform the following configuration tasks:

1. Define the local node as described in Configuring the Node. If you are providing passthrough DLUR support for downstream nodes, define the node as an APPN network node.

2. Configure connectivity to the APPN network. APPN connectivity requires at least a port and link station for independent traffic between the local node and the adjacent APPN network node, as described in Defining Connectivity Components.

3. Define a DLUR PU on the local node as described in Defining DLUR PUs. (The DLUR PU supports connectivity to the host.)

4. To configure DLUR to support LUs on the local node, you must add the LUs on the local node, as described in Configuring User Applications. The LUs can be configured to support 3270 display, 3270 printer, RJE, or LUA. Depending on the requirements of the user applications supported by the LUs, you may also need to perform further configuration.

To configure passthrough DLUR support for downstream nodes, you must perform the following configuration tasks:

1. Define the local node as an APPN network node (see Configuring the Node).

2. Configure connectivity to the downstream nodes. Configure ports and link stations for dependent traffic between the local node and each downstream node, as described in Defining Connectivity Components. (You do not need to define a DLUR PU to support DLUR for downstream nodes.)

3. A downstream node can support multiple PUs. In this case, each downstream PU is associated with a different link, so you need to configure multiple links between the SNAP-IX DLUR node and the downstream node, and you need to know the downstream PU name for each link.