CDP / LLDP

CDP (Cisco Discovery Protocol) / LLDP (Link Layer Discovery Protocol) – protocols, allowing network devices to announce they presence to other devices.

CDP – Cisco proprietary protocol, therefore it is working only with Cisco devices. LLDP – open protocol.

Usage examples

show cdp neighbors
show lldp neighbors

Best practice / configuration examples

CDP enabled by default on all cisco devices. Best practice is to disable CDP on customer-facing interfaces (and any other interfaces, facing to other company) and have CDP enable for internal-facing connections:

interface ehternet 1/10
  decription There is where our customer connected
  no cdp enabe

In Non-cisco networks (or mixed networks) best practice is to use LLDP. LLDP disabled by default on Cisco devices, so it is advised to enable it in mixed network.