350-501 Architecture Practice Question
An SP is migrating from an MPLS LDP-based network to Segment Routing. They want to ensure that existing LDP LSPs continue to work alongside SR LSPs during the migration. Which mechanism should be configured?
⚠ Common exam trap
Cisco often tests the misconception that SRGB or BGP-LU alone can enable coexistence, but only LDP-SR interworking provides the explicit label mapping and signaling integration required for LDP and SR LSPs to interoperate.
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
✓
LDP-SR interworking
LDP-SR interworking (RFC 8661) allows LDP and Segment Routing LSPs to coexist and interoperate during migration. It enables LDP-signaled LSPs to stitch with SR LSPs by mapping LDP labels to SR prefix-SIDs, ensuring end-to-end MPLS forwarding without service disruption. This mechanism is specifically designed for seamless coexistence without requiring a full network cutover.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
SRGB
Why it's wrong here
SRGB defines the label range for SR, not interworking.
- ✗
BGP-LU
Why it's wrong here
BGP-LU is for inter-AS label distribution, not for LDP-SR interworking.
- ✓
LDP-SR interworking
Why this is correct
This enables coexistence of LDP and SR LSPs.
- ✗
MPLS TE
Why it's wrong here
MPLS TE is for traffic engineering tunnels, not for LDP-SR coexistence.
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.