In most networks, we have several routers, switches, and more. We want to make management for networks easy, most of the admins take the help of CDP and LLDP to know about what type of devices are present in the network, the IP addresses, and how all the devices are connected with each other (which means the interface or port) and the information about which VLAN they belong.
Cisco discovery protocol
CDP (Cisco
discovery protocol) is a Cisco proprietary protocol which is designed by Cisco.
CDP is used to collect information about directly connected devices. We can collect
the hardware and protocol information about neighboring devices. This information
is very helpful when we do troubleshoot or document the network.
What information do we collect from neighbors?
- Device ID means the hostname of the neighbor.
- The local interface is the port on which CDP enables the device to receive the CDP packets.
- Hold time means the router's remaining amount of time is left to hold the information before the router is discarding it. The router discards the information if no more CDP packets are received. {You can choose the length from 10 – 255 seconds.}
- Capability means what is the capability of the neighbor it’s a router or switch or it’s a repeater.
- Platform means the type of Cisco device directly connected. In the previous output,
- Port ID means the neighbor device’s port or interface on which the CDP packets are multicasting.
Let's see the configuration and we will see some
interesting show commands.
Topology: -
- configure the topology as per the diagram
- configure the Hostname
- assign the IPs to their respective ports as per the topology
- configure CDP in global mode. or you can also configure CDP on an interface.
- make sure the router-1-core will collect all the information.
