1.2.10 Cisco Discovery Protocol (CDP) Overview
The first thing you want to know about your network is what is in it? Where are these components? How are they connected? Basically, you need a map. This topic explains how you can use Cisco Discovery Protocol (CDP) to create a map of your network.
CDP is a Cisco proprietary Layer 2 protocol that is used to gather information about Cisco devices which share the same data link. CDP is media and protocol independent and runs on all Cisco devices, such as routers, switches, and access servers.
The device sends periodic CDP advertisements to connected devices, as shown in the figure.
These advertisements share information about the type of device that is discovered, the name of the devices, and the number and type of the interfaces.
Because most network devices are connected to other devices, CDP can assist in network design decisions, troubleshooting, and making changes to equipment. CDP can also be used as a network discovery tool to determine the information about the neighboring devices. This information gathered from CDP can help build a logical topology of a network when documentation is missing or lacking in detail.