A data network links a number of host processors to alternative shared resources. In order to allocate a respective subset of the alternative shared resources to each host, a directory service of the network is programmed to present a respective view of the network to each host. For example, hosts on the same network loop may see a different picture of the network. When a host logs into the network, the directory service reports to the host information about the alternative shared resources that the host should use. The host then commences a sequence of data processing operations during which the host accesses only the shared resources that were reported to it by the directory service. The shared resources, for example, are ports of a storage subsystem, and a respective subset of the ports is assigned to each host to balance loading of the hosts on the ports.