In MPLS Layer 3 VPN implementations, what is used on the PE router to isolate potential overlapping routing information between different customers?

Question

Options

• Aroute targets
• BVRFs
• CVC IDs
• Dpseudowire IDs
• Epseudowire classes

• A
  4% (1)
• B
  91% (21)
• C
  4% (1)

Explanation

VRFs (Virtual Routing and Forwarding tables) are the mechanism PE routers use to maintain completely separate routing tables per customer, preventing overlapping IP address spaces from colliding - each customer gets their own isolated routing instance on the same physical device.

Why the distractors are wrong:

• A. Route targets are BGP extended communities used to control which routes get imported/exported between VRFs - they work alongside VRFs but don't themselves provide the isolation.
• C. VC IDs identify virtual circuits in Layer 2 VPN (pseudowire) contexts, not Layer 3 VPN routing isolation.
• D. Pseudowire IDs and E. Pseudowire classes both belong to Layer 2 MPLS services (like VPWS/L2VPN), not Layer 3 VPN architectures.

Memory tip: Think of VRFs as "virtual routers within a router" - each customer gets their own routing table, just like having a dedicated physical router, which is why overlapping 10.0.0.0/8 ranges from two different customers never conflict on the same PE.

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