300-420 Question 194
Single answerAn enterprise wants to connect multiple branch offices to its headquarters using an MPLS Layer 3 VPN. The branches require seamless communication with the headquarters and also need to communicate with each other without additional configuration at the branch routers. The service provider is responsible for managing the MPLS network. Which feature of MPLS Layer 3 VPNs ensures that the branch offices can communicate with each other and the headquarters without the need for additional configurations?
- A
Route Distinguisher (RD)
- B
Route Target (RT)
- C
Provider Edge (PE) routers
- D
Customer Edge (CE) routers
Show answer and explanation
Correct answer: B
Explanation
The Route Target (RT) is a key component in MPLS Layer 3 VPNs for enabling communication between sites. It allows for the export and import of routes between VPNs, ensuring that the branch office routes are correctly shared with the headquarters and other branches. This eliminates the need for additional configuration at the branch routers, as the RT ensures seamless route distribution across the MPLS network.
- A. Incorrect.
Route Distinguisher (RD) is used to make the customer's IP prefixes unique across the MPLS network but does not directly facilitate communication between branches.
- B. Correct.
Route Target (RT) is a BGP extended community attribute used to control route distribution among VPN sites, ensuring that routes are shared between branch offices and the headquarters.
- C. Incorrect.
Provider Edge (PE) routers are responsible for connecting the provider's MPLS network to the customer's network, but they do not control route sharing between VPN sites.
- D. Incorrect.
Customer Edge (CE) routers are located on the customer's premises and connect to the MPLS network via the PE routers. However, they do not manage inter-site routing.