1.7. Interpret network diagrams
The best way to look at, build, and troubleshoot network diagrams is to use CDP. Cisco Discovery Protocol (CDP) is a proprietary protocol designed by Cisco to help administrators collect information about both locally attached and remote devices. By using CDP, you can gather hardware and protocol information about neighbor devices, which is useful info for troubleshooting and documenting the network.
In the following sections, I am going to discuss the CDP timer and CDP commands used to verify your network.
1.7.1. Getting CDP Timers and Holdtime Information
The show cdp command (sh cdp for short) gives you information about two CDP global parameters that can be configured on Cisco devices:
CDP timer is how often ...