300-410 Infrastructure Services Practice Question
A service provider is deploying MPLS Traffic Engineering (TE) with RSVP-TE to guarantee bandwidth for critical traffic. The network uses OSPF as the IGP with TE extensions enabled. An engineer notices that a TE tunnel fails to establish because the path computation cannot find a path with sufficient bandwidth, even though the physical links have enough capacity. Which action should the engineer take to ensure that RSVP-TE can reserve bandwidth on the links?
⚠ Common exam trap
The trap here is assuming that enabling OSPF TE extensions or MPLS LDP is sufficient for RSVP-TE bandwidth reservation, when in fact the interface-level RSVP bandwidth configuration is required.
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
✓
Enable MPLS TE on the physical interfaces and configure the ip rsvp bandwidth command with the appropriate reservable bandwidth.
RSVP-TE requires that MPLS TE be enabled on the physical interface and that the interface be configured with the ip rsvp bandwidth command to specify the reservable bandwidth. Without this interface-level configuration, the TE tunnel cannot signal a reservation, and path computation fails due to lack of available bandwidth. OSPF TE extensions are already enabled, so the missing piece is the interface 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.
- ✓
Enable MPLS TE on the physical interfaces and configure the ip rsvp bandwidth command with the appropriate reservable bandwidth.
Why this is correct
For RSVP-TE to reserve bandwidth, MPLS TE must be enabled on the interface, and the ip rsvp bandwidth command must be configured to define the amount of reservable bandwidth. Without this, the TE tunnel cannot signal reservations, and path computation will fail because no bandwidth is available for reservation, even if the physical link has capacity.
- ✗
Enable MPLS LDP on all interfaces to ensure label distribution for the TE tunnel.
Why it's wrong here
MPLS LDP is used for label distribution in normal MPLS forwarding, but RSVP-TE uses its own signaling protocol to distribute labels and reserve resources. LDP is not required for TE tunnels and does not provide bandwidth reservation. Enabling LDP would not solve the issue of insufficient reservable bandwidth.
- ✗
Configure the mpls traffic-eng tunnels command under the OSPF process to advertise TE metrics.
Why it's wrong here
The mpls traffic-eng tunnels command is configured under OSPF to enable TE extensions and advertise TE link information, but it does not reserve bandwidth. It is necessary for path computation but not sufficient for reservation. The scenario states that OSPF TE extensions are already enabled, so this command is likely already present.
- ✗
Configure the ip rsvp bandwidth command under the OSPF process to allow RSVP to reserve bandwidth.
Why it's wrong here
The ip rsvp bandwidth command is an interface-level command, not an OSPF process command. Placing it under OSPF would not enable RSVP on the interface and would not allow bandwidth reservation. The command must be applied to each physical interface that will carry TE tunnels.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
Learn chapter
Introduction to ENARSI Exam and Network Fundamentals
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.
About these practice questions
Courseiva writes every 300-410 question from scratch — 1,401 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 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.