Introduction

Layer 2 discovery protocols such as CDP and LLDP share information with and discover information about neighboring (connected) devices.

The shared information includes host name, IP address, device type, etc.

CDP is Cisco proprietary protocol.

LLDP is an industry standard protocol (IEEE 802.1AB).

Because they share information about the devices in the network, they can be considered a security risk and are often not used. It is up to the network engineer/admin to decide if they want to use them in the network or not.