350-501 Architecture Practice Question
An MPLS Traffic Engineering LSP fails to establish. The RSVP signaling shows 'PathErr: Admission Control Failure'. The link has sufficient bandwidth but the headend reports a lack of resources. What is the most likely cause?
⚠ Common exam trap
Cisco often tests the distinction between physical link bandwidth and RSVP reservable bandwidth, trapping candidates who assume 'sufficient bandwidth' on the link automatically means RSVP can admit the LSP.
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 RSVP bandwidth is not configured on the interface or is set to 0
The 'PathErr: Admission Control Failure' with 'lack of resources' despite sufficient link bandwidth indicates that RSVP has no reservable bandwidth on the interface. This occurs when the 'ip rsvp bandwidth' command is missing or set to 0, preventing RSVP from admitting any LSP even if the physical link has capacity. The headend correctly reports the failure because the interface-level RSVP resource pool is exhausted or unconfigured.
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 tunnel is requesting more bandwidth than available on any path
Why it's wrong here
The problem states the link has sufficient bandwidth.
- ✗
The MPLS forwarding table is corrupted
Why it's wrong here
Corruption would cause label lookup failures, not RSVP signaling.
- ✗
The headend router does not have the correct destination address
Why it's wrong here
Destination address error would cause no path, not admission control failure.
- ✓
The RSVP bandwidth is not configured on the interface or is set to 0
Why this is correct
Without 'ip rsvp bandwidth' command on the interface, RSVP cannot allocate resources.
- ✗
The LSP is configured with a strict explicit path that is impossible
Why it's wrong here
Explicit path failure would show a different error like 'No route to destination'.
Go deeper
Related to this question
About these practice questions
Courseiva writes every 350-501 question from scratch — 971 in total, each with an explanation and a wrong-answer breakdown. None are copied from real exams or dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-501 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 350-501 exam.