350-501 Architecture Practice Question
In a carrier-supporting carrier (CSC) architecture, the customer carrier runs MPLS in its network. Which technology is used to exchange VPN routes between the provider carrier and the customer carrier?
⚠ Common exam trap
Cisco often tests the misconception that any IGP (like OSPF or EIGRP) or standard IPv4 BGP can exchange VPN routes between carriers, but only MP-BGP with the VPNv4 address family carries the necessary RD and RT attributes to support multi-tenant VPN separation in a CSC architecture.
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
✓
MP-BGP with VPNv4 address family
In a carrier-supporting-carrier (CSC) architecture, the customer carrier runs MPLS in its network and needs to exchange VPN routes (e.g., customer VPN prefixes) with the provider carrier. MP-BGP with the VPNv4 address family is the correct technology because it carries both the IPv4 prefix and the Route Distinguisher (RD), enabling the provider carrier to distinguish overlapping VPN routes from different customer VPNs. This is defined in RFC 4364 and is the standard inter-AS VPN option for CSC scenarios.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
OSPF
Why it's wrong here
OSPF is an IGP, not for VPN route exchange.
- ✓
MP-BGP with VPNv4 address family
Why this is correct
MP-BGP carries VPNv4 routes with labels.
- ✗
EIGRP
Why it's wrong here
EIGRP is an IGP, not for VPN route exchange.
- ✗
IPv4 BGP
Why it's wrong here
IPv4 BGP does not carry VPNv4 routes.
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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.