300-440 Question 165
Single answerA service provider is deploying an MPLS Layer 3 VPN to provide secure connectivity between multiple customer sites. The provider uses MP-BGP to distribute VPN routing information. Which of the following is a key characteristic of MPLS Layer 3 VPNs that enables the segregation of customer traffic?
- A
The use of VRFs (Virtual Routing and Forwarding) on the provider edge routers
- B
The use of VLAN tags to differentiate customer traffic
- C
The use of RSVP-TE tunnels to ensure traffic separation
- D
The use of GRE tunnels for customer traffic encapsulation
Show answer and explanation
Correct answer: A
Explanation
MPLS Layer 3 VPNs achieve customer traffic segregation through the use of VRFs on PE routers. Each customer is assigned a unique VRF, which isolates their routing information from other customers. MP-BGP is used to exchange VPN route information between PE routers, and MPLS labels are used to forward packets through the provider's MPLS backbone. This ensures secure and efficient connectivity for each customer.
- A. Correct.
Correct: VRFs are used on provider edge (PE) routers to maintain separate routing tables for each customer's traffic, ensuring traffic segregation and privacy.
- B. Incorrect.
Incorrect: VLAN tags are commonly used in Layer 2 networks, not MPLS Layer 3 VPNs. MPLS Layer 3 VPNs rely on VRFs and MPLS labels for traffic segregation.
- C. Incorrect.
Incorrect: RSVP-TE is a mechanism for traffic engineering and does not inherently provide the traffic segregation functionality required in MPLS Layer 3 VPNs.
- D. Incorrect.
Incorrect: GRE tunnels are used for general tunneling purposes, but MPLS Layer 3 VPNs use MPLS labels and VRFs for traffic segregation.