1. A machine-implemented method for configuring a plurality of 5 virtual networks using a plurality of physical resources of a network device, comprising: generating, by a processor, a hierarchical data structure having a plurality of layers for representing an instance of the network device; wherein a first layer from among the plurality of layers includes a base network object to represent a network, the base network object referenced by a first set of objects that represent the plurality of virtual networks using a plurality of network protocols, where the first set of objects includes a local area network (LAN) object and a storage area network (SAN) object; wherein a second layer from among the plurality of layers includes a port set object that defines a cluster of ports used by the network device and a second set of objects that reference the port set object and represent a plurality of virtual network protocols that are used by the plurality of virtual networks, and wherein a third layer from among the plurality of layers include a third set of object to represent the plurality of physical resources that are used by the plurality of virtual networks for communicating with other devices; using a processor-executable management application for configuring the plurality of virtual networks and selecting physical resources for the plurality of networks; and validating the plurality of virtual networks by using the data structure to check if there is any conflict in using the selected physical resources.