300-440 Question 155
Select 3An enterprise network is using MPLS Layer 3 VPNs to connect multiple branch offices. The network team needs to ensure end-to-end connectivity between branch offices while maintaining isolation between different customer traffic. Which of the following technologies must be implemented to achieve this setup?
- A
Multiprotocol BGP (MP-BGP) for VPN route distribution
- B
VRF (Virtual Routing and Forwarding) instances on provider edge (PE) routers
- C
GRE tunnels between customer edge (CE) routers
- D
Route Target (RT) configuration for importing and exporting routes
- E
IPSec encryption for securing traffic within the MPLS backbone
Show answer and explanation
Correct answers: A, B, D
Explanation
In an MPLS Layer 3 VPN, MP-BGP is used for distributing VPN routes, VRF instances on PE routers ensure traffic isolation, and Route Targets are configured for importing and exporting routes between VRFs. GRE tunnels and IPSec encryption are not core components of this setup, as MPLS itself provides the necessary connectivity and isolation.
- A. Correct.
MP-BGP is mandatory for distributing VPN routes between the provider edge (PE) routers in an MPLS Layer 3 VPN environment. It enables the exchange of VPN-IPv4 prefixes.
- B. Correct.
VRF instances are essential on PE routers to maintain customer traffic isolation. Each VRF represents a separate routing table for a specific customer.
- C. Incorrect.
GRE tunnels are not required in MPLS Layer 3 VPNs since MPLS itself provides connectivity between the customer edge routers via the provider network.
- D. Correct.
Route Targets (RTs) are used to control the import and export of VPN routes between VRFs. This is critical for ensuring proper route propagation in MPLS Layer 3 VPNs.
- E. Incorrect.
IPSec encryption is not natively required for MPLS Layer 3 VPNs, as MPLS provides traffic isolation; however, encryption might be added as an additional security layer if needed, but it is not part of the basic MPLS VPN setup.