300-440 Question 158
Select 3A company is implementing a DMVPN solution to connect multiple branch offices to the headquarters. They want to ensure that spoke-to-spoke communication is established on-demand without routing traffic through the hub after the initial setup. Which of the following technologies must be implemented to achieve this requirement?
- A
NHRP (Next Hop Resolution Protocol)
- B
IPSec with GRE Tunnel
- C
Split Tunneling
- D
Dynamic Routing Protocols (e.g., EIGRP, OSPF)
- E
Static Routing between Spokes
Show answer and explanation
Correct answers: A, B, D
Explanation
To achieve spoke-to-spoke communication in DMVPN, NHRP is used to resolve the IP addresses of spokes dynamically, and direct GRE tunnels are built between them. IPSec ensures secure communication over these tunnels. Dynamic routing protocols like EIGRP or OSPF are also necessary to manage routing between the hub and spokes, enabling dynamic reachability. Split tunneling and static routing are not applicable in this scenario.
- A. Correct.
NHRP (Next Hop Resolution Protocol) is essential for spoke-to-spoke communication in DMVPN. It allows the spokes to resolve each other's IP addresses dynamically and establish direct tunnels.
- B. Correct.
IPSec with GRE is necessary for secure communication over the DMVPN network. GRE allows for multiprotocol encapsulation, which is crucial for DMVPN functionality.
- C. Incorrect.
Split tunneling is not directly related to DMVPN or enabling spoke-to-spoke communication. It is used to manage traffic routing for VPN endpoints, typically in remote access scenarios.
- D. Correct.
Dynamic routing protocols like EIGRP or OSPF are required in DMVPN to propagate routing information between the hub and spokes, enabling dynamic reachability between spokes.
- E. Incorrect.
Static routing between spokes is not scalable in DMVPN setups and does not allow for on-demand spoke-to-spoke tunnels.