300-410 Layer 3 Technologies Practice Question
A network engineer is implementing MPLS Layer 3 VPNs. The engineer needs to configure a PE router to exchange VPNv4 routes with other PE routers. Which BGP configuration is required to enable the exchange of VPNv4 routes?
⚠ Common exam trap
It's easy for candidates to confuse the VRF address family with the VPNv4 address family, and thinking that configuring the VRF address family enables VPNv4 route exchange.
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
✓
address-family vpnv4
In MPLS Layer 3 VPNs, PE routers use Multiprotocol BGP (MP-BGP) to exchange VPNv4 routes. The VPNv4 address family is specifically designed for this purpose. Configuring address-family vpnv4 and activating neighbors under it enables the exchange of VPNv4 prefixes, which include the route distinguisher and label information. Other address families like ipv4 unicast or ipv4 vrf are used for different purposes.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
address-family vpnv4
Why this is correct
The address-family vpnv4 command is used to enter the VPNv4 address family configuration mode. Within this mode, you can activate BGP neighbors to exchange VPNv4 routes. This is required for PE routers to exchange VPNv4 prefixes, which include the route distinguisher and VPN label. Without this address family, PE routers cannot exchange VPN routing information.
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address-family ipv6 unicast
Why it's wrong here
The address-family ipv6 unicast command is used for IPv6 unicast routing. It is not related to VPNv4 route exchange, which is for IPv4 VPNs. MPLS Layer 3 VPNs can support IPv6, but that would use the VPNv6 address family. For VPNv4, the correct address family is vpnv4.
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address-family ipv4 unicast
Why it's wrong here
The address-family ipv4 unicast command is used for standard IPv4 unicast routing. While it is used for global BGP peering and for PE-CE peering in some designs, it does not carry VPNv4 routes. VPNv4 routes require the VPNv4 address family. Therefore, this command alone does not enable VPNv4 route exchange.
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address-family ipv4 vrf CUSTOMER
Why it's wrong here
The address-family ipv4 vrf CUSTOMER command is used to enter the VRF address family configuration mode for a specific VRF. This is necessary for configuring BGP peering with CE routers within that VRF, but it does not enable the exchange of VPNv4 routes between PE routers. VPNv4 routes are exchanged using the VPNv4 address family, which is configured with address-family vpnv4.
Go deeper
Related to this question
Learn chapter
OSPF Route Summarization and Filtering
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.
Key term
MP-BGP for VPN
MP-BGP for VPN is an extension of the Border Gateway Protocol that carries multiple types of network layer information to enable scalable, isolated virtual private networks over a shared provider infrastructure.
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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.