300-420 Question 163
Select 3An enterprise organization is deploying an MPLS Layer 3 VPN solution to interconnect multiple branch offices with its central data center. The provider's MPLS backbone is already configured. The enterprise requires segmentation between different departments (Finance, HR, and IT) while ensuring communication within each department's branch offices and data center. Which of the following steps are necessary for the service provider to configure on their network to meet this requirement?
- A
Configure VRFs on the provider edge (PE) routers and assign interfaces to appropriate VRFs.
- B
Implement route targets (RTs) to control route import/export between VRFs.
- C
Enable BGP on the customer edge (CE) routers to exchange routing information with the PE routers.
- D
Configure MP-BGP on the provider edge (PE) routers to exchange VPNv4 routes across the MPLS backbone.
- E
Deploy separate MPLS labels for each VRF to ensure data plane segregation.
Show answer and explanation
Correct answers: A, B, D
Explanation
In an MPLS Layer 3 VPN, VRFs are created on the PE routers to segregate traffic. RTs are used to manage route import/export policies between VRFs, and MP-BGP is used to advertise VPNv4 routes across the MPLS backbone. While the CE routers do not necessarily require BGP, the MPLS backbone dynamically handles label distribution without the need for explicitly separate labels for each VRF.
- A. Correct.
Correct: Configuring VRFs on the PE routers is essential for segmenting traffic for different departments. Each VRF represents a separate routing table, ensuring traffic isolation.
- B. Correct.
Correct: Route targets (RTs) are used in MPLS Layer 3 VPNs to control which routes are imported and exported between VRFs, enabling inter-VRF communication where necessary.
- C. Incorrect.
Incorrect: BGP is not mandatory on the CE routers for MPLS Layer 3 VPNs. Static routing or another routing protocol (e.g., OSPF) can also be used between CE and PE.
- D. Correct.
Correct: MP-BGP is required on the PE routers to exchange VPNv4 routes across the MPLS backbone. This ensures proper routing between sites within the same VRF.
- E. Incorrect.
Incorrect: MPLS labels do not need to be separately deployed for each VRF. MPLS uses label stacking to identify the VRF and forward traffic appropriately.