300-420 Question 187
Single answerA large enterprise network is deploying DMVPN to connect multiple branch offices to the headquarters and to each other. The network engineer wants to ensure that branches can communicate directly with each other without forwarding traffic through the headquarters router. Which DMVPN phase should the engineer implement to achieve this requirement?
- A
DMVPN Phase 1
- B
DMVPN Phase 2
- C
DMVPN Phase 3
- D
DMVPN Phase 4
Show answer and explanation
Correct answer: B
Explanation
In DMVPN Phase 2, spokes can dynamically establish direct tunnels to other spokes for communication, bypassing the hub router. This is achieved through the Next Hop Resolution Protocol (NHRP), which resolves the public IP addresses of other spokes. DMVPN Phase 1 does not support direct communication between spokes, and Phase 3 introduces route redirection via the hub, which adds complexity. Phase 4 is not a valid DMVPN phase.
- A. Incorrect.
DMVPN Phase 1 only supports hub-and-spoke topology, meaning all traffic between spokes must be routed through the hub. This does not allow direct communication between branch offices.
- B. Correct.
DMVPN Phase 2 supports direct spoke-to-spoke communication by dynamically establishing tunnels between spokes without routing traffic through the hub. This satisfies the requirement.
- C. Incorrect.
DMVPN Phase 3 enhances scalability by allowing spoke-to-spoke communication, but it relies on the hub to provide route redirection using NHRP shortcuts. While this can enable spoke-to-spoke traffic, it is less optimal for direct communication compared to Phase 2.
- D. Incorrect.
There is no DMVPN Phase 4. This is a distractor option.