350-501 Architecture Practice Question
Which MPLS label is used to identify the egress PE in a Layer 3 MPLS VPN?
⚠ Common exam trap
Cisco often tests the distinction between the transport label (used for core forwarding) and the VPN label (used for service identification), and candidates mistakenly think the LDP label or IGP label serves the egress PE identification role because they associate label distribution with routing protocols.
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
✓
VPN label
In a Layer 3 MPLS VPN, the VPN label (also known as the service label) is assigned by the egress PE router and advertised via MP-BGP (RFC 4364). It uniquely identifies the VPN forwarding instance (VRF) on the egress PE, allowing the correct per-VPN forwarding decision to be made after the transport label has been removed. Without the VPN label, the egress PE would not know which VRF or customer-facing interface should receive the packet.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Transport label
Why it's wrong here
The transport label is used for label switching within the core, not to identify the egress PE.
- ✓
VPN label
Why this is correct
The VPN label is used by the egress PE to identify the correct VRF.
- ✗
LDP label
Why it's wrong here
LDP labels are used for LSPs, not for VPN identification.
- ✗
IGP label
Why it's wrong here
There is no standard 'IGP label' term in MPLS.
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.