300-410 Question 118
Single answerAn OSPF network has been partially configured with two discontiguous areas: Area 0 and Area 1. You notice that Area 1 cannot reach the backbone area, Area 0, due to a missing direct connection. To resolve this, a virtual link is proposed. Which of the following is a requirement for successfully configuring the OSPF virtual link?
- A
The transit area used for the virtual link must be a stub area.
- B
The routers forming the virtual link must share a common area.
- C
The virtual link must be configured between the ABR of Area 0 and the ABR of Area 1.
- D
A virtual link can only be configured in OSPF networks with IPv6 enabled.
Show answer and explanation
Correct answer: B
Explanation
A virtual link in OSPF is used to connect discontiguous areas to the backbone area (Area 0). For a virtual link to function, the routers on either side of the virtual link must share a common area, known as the transit area. This ensures proper routing and communication. Stub areas cannot be used as transit areas, and virtual links are not limited to IPv6 networks.
- A. Incorrect.
Incorrect: The transit area used for a virtual link cannot be a stub area. Stub areas prevent the propagation of external routes, making them unsuitable for virtual links.
- B. Correct.
Correct: The routers forming the virtual link must share a common area, which serves as the transit area. This is a key requirement in OSPF virtual link configuration.
- C. Incorrect.
Incorrect: A virtual link does not have to be configured directly between the ABR of Area 0 and the ABR of Area 1. Instead, it connects two ABRs through a common transit area.
- D. Incorrect.
Incorrect: Virtual links are protocol-neutral within OSPF and can be configured in both IPv4 and IPv6 networks. IPv6 is not a specific requirement.