A network technician is configuring Layer 2 neighbor discovery protocols on a Cisco Catalyst switch connected to non-Cisco IP phones and third-party switches. Which two statements regarding the default operations and characteristics of CDP and LLDP are accurate?
- LLDP is an open-standard protocol defined under IEEE 802.1AB, whereas CDP is a Cisco-proprietary protocol.Answer
- BCDP sends discovery messages using TLVs, whereas LLDP uses fixed binary frame headers without TLVs.
- CDP is enabled globally by default on Cisco IOS switches, while LLDP typically requires global enablement using the 'lldp run' command.Answer
- DLLDP automatically negotiates native VLAN IDs across trunk links, preventing native VLAN mismatch errors.
Answer
The two correct statements are that LLDP is an IEEE 802.1AB open standard while CDP is Cisco-proprietary, and that CDP is enabled by default on Cisco IOS switches while LLDP must be globally enabled using the 'lldp run' command.
LLDP is defined by IEEE 802.1AB as an open standard protocol, making it suitable for environments with equipment from multiple vendors, whereas CDP is a Cisco-proprietary protocol. Furthermore, Cisco switches default to having CDP enabled out-of-the-box, while LLDP must be globally enabled using the global configuration command 'lldp run'.
Step-by-Step Solution
Key Concept
Layer 2 Discovery Protocol Differences (CDP vs LLDP)