300-410 Question 198
Single answerYou are configuring a DMVPN network to enable spoke-to-spoke communication without requiring all traffic to pass through the hub router. Which configuration change ensures direct communication between spokes while maintaining scalability in the network?
- A
Enable NHRP shortcut and redirect on the hub router.
- B
Configure static GRE tunnels between spoke routers.
- C
Enable OSPF as the routing protocol between all spokes.
- D
Disable split-horizon on the hub router.
Show answer and explanation
Correct answer: A
Explanation
In a DMVPN network, NHRP (Next Hop Resolution Protocol) shortcut and redirect features allow spoke routers to dynamically establish direct tunnels to other spokes, bypassing the hub for data plane traffic. This ensures efficient spoke-to-spoke communication while maintaining the scalability and dynamic nature of the DMVPN architecture. Other options, such as static GRE tunnels or disabling split-horizon, may work in limited scenarios but are not scalable or efficient solutions for modern DMVPN deployments.
- A. Correct.
Enabling NHRP shortcut and redirect on the hub router allows spokes to dynamically learn the IP addresses of other spokes, enabling direct spoke-to-spoke communication without routing all traffic through the hub. This is the correct approach in a scalable DMVPN design.
- B. Incorrect.
Configuring static GRE tunnels between spoke routers is not scalable in a DMVPN environment, as it requires manual configuration for every spoke-to-spoke connection, defeating the purpose of dynamic DMVPN operation.
- C. Incorrect.
While OSPF can be used as the routing protocol in the DMVPN network, it does not inherently enable direct spoke-to-spoke communication. Additional configuration, such as NHRP, is required.
- D. Incorrect.
Disabling split-horizon on the hub router is applicable in some hub-and-spoke designs, but it does not directly enable spoke-to-spoke communication. It is not a recommended solution in modern DMVPN setups.