LLDP Configuration on Single Interface in Multivendor Network
Refer to the exhibit. A multivendor network exists and the company is implementing VoIP over the network for the first time. Which configuration is needed to implement the neighbor discovery protocol on the interface and allow it to remain off for the remaining interfaces?
Community Insight
The question tests whether you know LLDP must be enabled per-interface using 'lldp transmit' and 'lldp receive' commands, not with the nonexistent 'lldp enable' command, and that 'no cdp run' removes the Cisco-proprietary CDP from a multivendor environment.
This CCNA 200-301 question tests configuring an industry-standard neighbor discovery protocol (LLDP) on just one interface of a multivendor network carrying new VoIP traffic, while leaving the protocol off everywhere else. The correct answer enables LLDP only at the interface level using the valid commands 'lldp transmit' and 'lldp receive' under interface Gi1/0/1, after disabling the Cisco-proprietary CDP globally.
Most learners pick Option A because it looks reasonable (global 'lldp run' then 'lldp enable' on the interface), but 'lldp enable' is not a valid Cisco IOS command — LLDP on an interface is turned on with 'lldp transmit' and 'lldp receive'.
Community Discussion (16 comments)
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Expert Analysis
Why the Answer Is Correct
Option B is the only choice that uses valid, real Cisco IOS commands to activate LLDP on a single interface. Under interface GigabitEthernet1/0/1, the commands lldp transmit and lldp receive are exactly how LLDP advertisement and reception are turned on for a specific port, which satisfies the requirement that the protocol stay off on all remaining interfaces. The leading no cdp run command is also appropriate here: because CDP is Cisco-proprietary and the network is explicitly multivendor, disabling CDP globally is the correct move before relying on the open-standard LLDP. Even though a complete production deployment would also include a global lldp run to enable LLDP at the global level on Cisco IOS, Option B is the only answer whose interface-level syntax is fully valid and matches the question's stated goal.
Why the Other Options Are Wrong
Option A uses lldp enable under the interface, and no such command exists in Cisco IOS — the only interface-level LLDP toggles are lldp transmit and lldp receive, so this configuration would be rejected. Option C is doubly broken: it misspells the prompt as SW1(contig)#, places lldp enable (again nonexistent) in global config mode, and puts lldp run — a global command — under the interface, which is invalid. Option D is wrong on two counts: it uses cdp enable (not a valid command; CDP uses cdp run), and more importantly CDP is Cisco-proprietary, so enabling it would not solve the multivendor neighbor-discovery requirement that LLDP (an open IETF/IEEE standard) addresses.
Community Comment Notes
Several commenters correctly flagged that "lldp enable" is not a real command, with dropspablo flatly stating "Command \"lldp enable\" does not exist!" and no_blink404 agreeing that this rules out Option A. picho707 argued that B is "the best of all the crappy answers provided" because global lldp run would enable LLDP on all ports, contradicting the question's requirement. pikos1 and 3040636 both pointed out that Option B omits the global lldp run command needed for LLDP to actually function, while AbdullahMohammad251 acknowledged this caveat yet still concluded "B is correct" because the interface-level commands are valid and the other options contain outright invalid syntax. henrygonzlab preferred Option A, reasoning that without global lldp run LLDP will not work — but that argument rests on the nonexistent lldp enable command, so it cannot be the intended answer.
Exam Strategy
On neighbor-discovery questions, first identify whether the scenario is multivendor (use LLDP) or Cisco-only (CDP). Remember that LLDP is off by default on Cisco IOS and is enabled per-interface with lldp transmit/lldp receive — there is no lldp enable command, and cdp run is a global command, not an interface-level one.
Frequently Asked Questions
Why is 'lldp enable' not a valid command for enabling LLDP on an interface?
Cisco IOS does not provide an 'lldp enable' command. Instead, LLDP on an interface is turned on using two separate commands: 'lldp transmit' to send LLDP advertisements and 'lldp receive' to accept them.
Why does the configuration start with 'no cdp run' before enabling LLDP?
CDP is Cisco-proprietary and won't interoperate with non-Cisco VoIP phones or switches. Because the scenario is explicitly multivendor, disabling CDP globally and relying on the open-standard LLDP is the appropriate choice.
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lldp run) and then activates the protocol specifically on the indicated interface (lldp enable). B:no cdp rundisables CDP, butlldp transmitandlldp receiveonly configure individual transmission/reception; without the globallldp runcommand, LLDP will not work. C: It uses incorrect syntax (lldp enablein global configuration mode andlldp rununder the interface). D: CDP is a Cisco proprietary protocol and does not operate in a standard way with equipment from other vendors (multivendor environments).