Abstract: The present invention is a system for discovering the topology of a network. A source node may issue ping symbols that are addressed to specific, potentially existing, target nodes. An echo symbol is always returned. The type of ping symbol determines over how many bridges the ping symbol may propagate. The type of echo symbol identifies if the addressed node is a leaf node, a non-existing node, an operating bridge node, or a non-operating bridge node. The responsibility for transforming pings into echoes belongs only to the bridge nodes. A sequence of issued ping symbols and returned echo symbols allows a source node to discover the topology of the entire network.