# Cisco Discovery Protocol

CDP is media- and protocol-independent and runs on all Cisco-manufactured equipment, including routers, bridges, access and communications servers, and switches. CDP allows network management applications to dynamically discover Cisco devices that are neighbors of already-known devices, in particular, neighbors running lower-layer, transparent protocols. CDP runs on all media that support Subnetwork Access Protocol (SNAP). CDP also runs over the data link layer only, not the network layer. Cisco devices do not forward CDP packets.