Disclosed are apparatus and methods for discovering topology in a storage area network having a plurality of VSANs in a network fabric is disclosed. The VSANs include a first VSAN having a plurality of network devices. The method includes the following operations: (a) defining a first one of the network devices of the first VSAN as a Topology Update (TU) Owner, wherein the other network devices of the first VSAN are not defined as TU Owners, (b) at the first network device, receiving data that indicates a topology change in the first VSAN, (c) at the first network device, generating or updating one or more TU database(s) for the plurality of VSANs of the network fabric based on the received topology change, and (d) the first network device causing the topology change to be propagated in the form of a Topology Update across the network fabric to network devices in the plurality of VSANs of such network fabric.