Locate resource: CP network broadcast initiation

Figure 1. Locate resource: CP network broadcast initiation

Diagram of locate resource: control point (CP) network broadcast initiation.

A resource in NN1 requests a search for a resource on NN4. As network node server of the originating LU, NN1 looks for the target resource in the directory database. NN1 has no knowledge of the location of the target resource. NN1 initiates a resource discovery search for the target, which contains no session-specific information.
NN1 has no APPN-domain end nodes, therefore no domain broadcast occurs. There is no central directory server in the network; therefore, NN1 sends a broadcast search request to every network node with which NN1 has CP-CP sessions.
Each network node that receives the network broadcast request forwards the request to every network node with which it has CP-CP sessions. (It does not forward the request to the node from which it received the broadcast request.) Those nodes then begin searching their respective domains for the target resource. (For broadcast-specific flows for those nodes, see Figure 1.)
NN2 searches its domain for the resource. (Flows are not shown; see Figure 1.) NN2 does not locate the resource. However, NN2 does not reply to NN1 until it has received a reply from all of the nodes to which it forwarded the request. NN3 does not locate the resource in its own domain and replies to NN2.
NN2 now returns a negative reply to NN1 because NN2 has exhausted its search logic.
NN4 owns the resource; therefore, it returns a positive reply to NN1.
Because the resource discovery search located the resource, NN1 sends a search to the target containing the original session-specific information.
The target is found.