A network engineer is configuring Layer 2 discovery protocols across an enterprise network that includes both Cisco and non-Cisco hardware. Which two statements correctly describe the operational characteristics, default timers, or CLI configuration syntax for CDP and LLDP on Cisco Catalyst switches? (Select two)
- CDP uses default advertisement and holdtime timers of 60 seconds and 180 seconds respectively, whereas LLDP defaults to a 30-second advertisement timer and a 120-second holdtime.Answer
- When LLDP is enabled globally, bidirectional neighbor discovery on a specific interface requires both 'lldp transmit' and 'lldp receive' commands under interface configuration mode.Answer
- CExecuting the global configuration command 'no cdp run' disables CDP on the local interface while permitting the switch to continue transmitting CDP frames on trunk ports.
- DLLDP is an IEEE 802.3 standard protocol that utilizes proprietary Type-Length-Value (TLV) fields incompatible with non-Cisco devices.
Answer
The two correct statements are: 1) CDP defaults to 60-second update and 180-second holdtime timers while LLDP defaults to 30-second update and 120-second holdtime timers; and 2) LLDP requires both 'lldp transmit' and 'lldp receive' interface commands for bidirectional operation once enabled globally.
CDP operates using a 60-second update interval and a 180-second holdtime by default. In contrast, LLDP uses a 30-second update interval and a 120-second holdtime. Additionally, LLDP interface submode commands decouple transmitting and receiving discovery frames into 'lldp transmit' and 'lldp receive', both of which are required for bidirectional neighbor identification.
Step-by-Step Solution
Key Concept
CDP and LLDP operational differences, default timers, and interface configuration commands