A directed search is sent by directory services to the node recorded as the owner of the requested LU to verify the information. A directed search can be sent to a network node server from an end node and to an end node from a network node server. A directed search can also be sent from a network node to a central directory server when the network node does not have information on the location of the destination logical unit or following a failed search.

Directed searches are always sent to the network node server of the destination resource. This is because the topology database does not allow a network node to compute a Locate path all the way to an end node in the domain of another network node (that is, to an end node that is served by a different network node).

A directed Locate search request is a request that is sent along a predefined path from one network node to another network node. The origin network node calculates a path of CP-CP session hops to the target network node and appends the routing information to the search. Each network node along the path relies on that routing information for choosing the next hop and ensuring that the search travels directly to the destination network node.

Figure 1 demonstrates how a network node (NN4, in the example) verifies the location of LUA. The request to locate LUA originates from ENB, which sends a locate (FIND) request to its network node server. The directory database in NN4 has the information about the location of LUA and sends a directed search. Because LUA is located in an end node (ENA), the directed search is addressed to ENA's network node server (NN1).

The search contains the path over which the directed search should be sent. Each network node along the path forwards the directed search to the next network node. The last network node on the path (NN1) forwards the search to the end node (ENA).

Figure 1. Directed search - verifying resource location

The positive reply is returned along the same path as depicted in Figure 2.

Figure 2. Directed search - positive reply