Refer to the exhibit. A customer wants to adopt a dynamic site-to-site VPN solution to secure communication for VoIP, video, and FTP traffic between the remote branches and the headquarters. The…

DMVPN Phase 2 Hub and Spoke design allows direct spoke-to-spoke tunnels but requires spokes to learn all remote spoke routes, which can consume significant memory on branch routers and is not suitable for memory-limited devices.

DMVPN Phase 3 Hub and Spoke design allows spokes to establish direct spoke-to-spoke tunnels dynamically without intervention from the hub, fulfilling the direct communication requirement and reducing hub traffic. It also uses NHRP redirects, meaning spokes do not need to learn all remote spoke routes, thus conserving memory on resource-constrained branch routers.

DMVPN Phase 3 Hierarchical design introduces more complexity and potentially more overhead for branch routers, which contradicts the requirement for limited memory devices.

DMVPN Phase 1 Hub and Spoke design forces all spoke-to-spoke traffic to pass through the hub, which does not meet the requirement for direct branch communication and increased hub traffic.