InfiniBand is becoming an industry standard both for communication between processing nodes and I/O devices, and for interprocessor communication. Instead of using a shared bus, InfiniBand employs an arbitrary (possibly irregular) switched point-to-point network. InfiniBand specification defines a basic management infrastructure that is responsible for subnet configuration, activation, and fault tolerance. After the detection of a topology change, management entities collect the current subnet topology. The topology discovery algorithm is one of the management issues that are outside the scope of the current specification. Preliminary implementations obtain the entire topological information each time a change is detected. In this work, we present and analyze an optimized implementation, based on exploring only the region that has been affected by the change.