Acing the CCNA Exam, Volume 2

1 Cisco Discovery Protocol and Link Layer Discovery Protocol

This chapter covers

• The purpose of Layer 2 discovery protocols
• How neighboring Cisco devices use Cisco Discovery Protocol to share information
• CDP’s industry-standard equivalent: Link Layer Discovery Protocol

In a perfect world, all networks would be perfectly documented, with up-to-date network diagrams and other documents detailing the routers, switches, firewalls, and other devices that make up the network infrastructure, how they are connected, their IP addresses, etc. In reality, that’s often not the case: people cut corners, changes go undocumented, or perhaps the network was never properly documented in the first place.

In either case, the result is often that the network documentation ...