Many network management systems can discover the topology of a network. As with inventory, some do it once (i.e., “get and forget”). Better ones continually monitor for topology changes. Lower-end tools, however, separate the topology from the management system. They get a map for the sake of getting a map but they don’t use it.
All maps are not created equal.
Some are extremely basic. Others contain interesting information about the connections and the devices displayed. Topology discovery covers both device interconnections and the connections between access switches and the servers and end user hosts. Providing both forms of topology discovery should be a fundamental capability of an advanced NMS, not an afterthought provided by a secondary product.