300-420 Question 161
Select 3An enterprise customer with multiple branch offices has requested a network design that supports secure, scalable, and isolated connectivity between these branches over a shared MPLS service provider network. Which of the following design considerations are critical for successfully implementing MPLS Layer 3 VPNs in this scenario?
- A
Ensure that each VPN customer has a unique Route Distinguisher (RD) to distinguish overlapping IP address spaces.
- B
Configure the Provider Edge (PE) routers to exchange VPNv4 routes with each other using BGP.
- C
Deploy MPLS Traffic Engineering (TE) to ensure deterministic path selection for all VPN traffic.
- D
Implement VRF (Virtual Routing and Forwarding) instances on PE routers for each customer VPN.
- E
Enable OSPF as the sole routing protocol between Customer Edge (CE) routers and Provider Edge (PE) routers.
Show answer and explanation
Correct answers: A, B, D
Explanation
MPLS Layer 3 VPNs provide secure and isolated connectivity over a shared provider network by using technologies such as RDs to distinguish overlapping IP spaces, BGP for route propagation, and VRFs to maintain separate routing tables per customer. Traffic Engineering and specific routing protocols like OSPF are not inherent requirements for MPLS Layer 3 VPN implementation but may be used depending on specific design needs.
- A. Correct.
Correct: Route Distinguishers (RDs) are used to uniquely identify and separate overlapping IP address spaces for different VPN customers in an MPLS Layer 3 VPN environment.
- B. Correct.
Correct: PE routers must exchange VPNv4 routes via BGP to ensure routing information is properly propagated between VPN sites.
- C. Incorrect.
Incorrect: While MPLS Traffic Engineering (TE) can optimize traffic paths, it is not a mandatory requirement for MPLS Layer 3 VPN functionality.
- D. Correct.
Correct: VRFs are required on PE routers to maintain separate routing tables for each customer VPN, ensuring traffic isolation and proper forwarding.
- E. Incorrect.
Incorrect: OSPF is not a mandatory protocol for CE-PE communication. MPLS Layer 3 VPN supports multiple routing protocols, including OSPF, BGP, EIGRP, and static routing, based on customer requirements.