350-501 Architecture Practice Question
A network architect is designing a Segment Routing (SR) network for a service provider with a requirement for fast convergence upon node failure. The network uses IS-IS as the IGP with segment routing extensions. Which design choice BEST ensures that the network can achieve sub-50ms convergence without relying on any signaling protocol beyond the IGP?
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 TI-LFA (Topology Independent Loop-Free Alternate) on all ISIS interfaces
TI-LFA (Topology Independent Loop-Free Alternate) provides sub-50ms convergence by precomputing backup paths using only the IGP (IS-IS with SR extensions), without requiring any additional signaling protocol. Option A is wrong because BFD with static routes offers fast detection but does not provide a backup path automatically; it must be combined with a protection mechanism like FRR. Option B is wrong because RSVP-TE Fast Reroute relies on RSVP signaling and TE tunnels, which are beyond the IGP-only requirement. Option D is wrong because LDP is a separate signaling protocol that requires LDP FRR and path protection, again adding signaling overhead beyond the IGP.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Deploy BFD with static routes for fast detection
Why it's wrong here
BFD with static routes provides fast failure detection but does not provide an automatic backup path; it must be combined with a protection mechanism, which often involves additional signaling or static configuration, and thus does not meet the requirement of no signaling beyond the IGP.
- ✗
Configure RSVP-TE with Fast Reroute on all label-switched paths
Why it's wrong here
RSVP-TE requires explicit signaling to establish tunnels and Fast Reroute backups, which goes beyond the IGP and violates the requirement of no additional signaling.
- ✓
Enable TI-LFA (Topology Independent Loop-Free Alternate) on all ISIS interfaces
Why this is correct
TI-LFA computes backup paths using only IGP information (IS-IS with segment routing extensions), ensuring sub-50ms convergence without any additional signaling protocol, making it the best choice.
- ✗
Use LDP with LDP FRR and path protection
Why it's wrong here
LDP is a separate signaling protocol, and LDP FRR still relies on LDP for label distribution, which introduces additional signaling beyond the IGP.
Go deeper
Related to this question
About these practice questions
This 350-501 question is part of Courseiva's 971-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam 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.