mediumMultiple Choice
300-410 Practice Question: Runs the following command on Router R1: R1# show…
A network engineer runs the following command on Router R1:
R1# show mpls l2transport vc 100 detail
Local interface: Gi0/0/0 up, line protocol up Destination: 10.0.0.2, VC ID: 100, VC status: down Last error: No remote LDP session
Based on this output, what is the most likely cause of the VC being down?
⚠ Common exam trap
300-410 often tests whether candidates can read the 'Last error' field literally — the trap is picking 'IP unreachable' because LDP depends on IP, but the output names the LDP session itself as the missing component.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The LDP session between the routers is not established.
The output explicitly states 'Last error: No remote LDP session,' which means the local router cannot establish an LDP session with the remote PE (10.0.0.2). In AToM (Any Transport over MPLS) / L2VPN pseudowire setups, the VC status depends on an operational LDP session between the two PEs to exchange VC labels. Without that LDP session, the VC cannot come up regardless of interface or VC ID configuration.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The local interface Gi0/0/0 is administratively down.
Why it's wrong here
The output shows Gi0/0/0 as up with line protocol up, so it is not administratively down; the reported last error is no remote LDP session. The option is tempting because an interface problem would also bring the VC down, but the interface state here is already confirmed up.
- ✗
The remote router 10.0.0.2 is not reachable via IP.
Why it's wrong here
IP reachability to 10.0.0.2 is required for the targeted LDP session, but the error names the missing LDP session specifically, not an unreachable peer. If the destination were unreachable, the output would show no route or an LDP peer in a non-operational state.
- ✓
The LDP session between the routers is not established.
Why this is correct
The "No remote LDP session" error directly indicates that the targeted LDP session carrying the VC label binding has not formed between the PE routers. AToM pseudowires require a targeted LDP session to exchange VC labels, so without it the VC remains down regardless of interface state.
- ✗
The VC ID 100 is mismatched on the remote router.
Why it's wrong here
A VC ID mismatch produces a different error — typically 'VC ID mismatch' or a remote VC down state — not 'No remote LDP session'. The LDP session itself must form before VC ID negotiation occurs. VC ID matching is relevant once the session is established and labels are exchanged.
Go deeper
Related to this question
Learn chapter
MPLS L3VPN Basics
Key term
LDP Protocol
LDP, or Label Distribution Protocol, is a protocol that routers use to automatically exchange labels that enable MPLS (Multiprotocol Label Switching) to create fast, efficient paths for data packets across a network.
Key term
MPLS Label Distribution
MPLS Label Distribution is the process by which routers exchange labels that tell them how to forward packets across a network without looking at the IP address each time.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 300-410 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 300-410 exam.