Cisco CCNA (200-301)Network AccessMedium
A network engineer must add a switch that is a mix of Cisco and third-party (non-Cisco) equipment and wants to view neighbor device information (platform, port ID, capabilities) from the non-Cisco devices as well as the Cisco ones. Which protocol should be enabled to accomplish this on the non-Cisco devices?
- ACDP, since it works across all vendors by default
- BLLDP, an IEEE 802.1AB vendor-neutral standard supported broadly
- CDTP, to negotiate neighbor discovery
- DVTP, to synchronize neighbor information across the domain
Show answer & explanationAnswer & explanation
Correct answer: B. LLDP, an IEEE 802.1AB vendor-neutral standard supported broadly
CDP (Cisco Discovery Protocol) is Cisco-proprietary and generally only runs on Cisco devices, so it won't reveal information about third-party neighbors. LLDP (Link Layer Discovery Protocol) is an open IEEE 802.1AB standard supported by many vendors, allowing neighbor discovery across a mixed-vendor network.
Why the other options are wrong
- A. CDP is proprietary to Cisco and typically not supported on non-Cisco devices.
- C. DTP only negotiates trunking, it is not a neighbor discovery protocol.
- D. VTP synchronizes VLAN database information, unrelated to neighbor discovery.
CDP vs LLDP
CDP is Cisco's proprietary Layer 2 neighbor discovery protocol, while LLDP (IEEE 802.1AB) is an open standard supported across vendors.
- CDP: Cisco-only, enabled by default on Cisco gear
- LLDP: open standard, works with mixed-vendor equipment
- Both operate at Layer 2 and share info like device ID, port ID, capabilities
- Both can be enabled simultaneously on Cisco switches
Memory trick: CDP speaks only Cisco; LLDP speaks every language.