Topology MIBs are an important data source for discovering neighboring systems. When the topology MIB data source is enabled, autodiscovery uses the IP addresses from these sources to discover related systems. Examples of topology MIB data sources include the following:
IP addresses stored in the Cisco Discovery Protocol (CDP) table
IP addresses stored in the MIB-II atmInterfaceConfTable table
In some cases, however, a system is not discovered for each IP address, if, for example, there is no route to the network from the host on which the IP Manager is running. This situation can occur when security restrictions are designed to prevent access between two separate networks.