The Next Hop Resolution Protocol (NHRP) redirect is not a strict requirement for FlexVPN spoke- to-spoke tunnels to function. NHRP redirect is typically used in DMVPN (Dynamic Multipoint Virtual Private Network) deployments to optimize the routing of traffic between spoke-to-spoke connections by allowing the hub to inform spokes about more efficient paths In a FlexVPN deployment, spokes send resolution requests to the hub for spoke-to-spoke communication. These resolution requests are typically related to Next Hop Resolution Protocol (NHRP) operations. NHRP is used in FlexVPN to dynamically map the public IP addresses of spokes to their private IP addresses, facilitating spoke-to-spoke communication without having to route all traffic through the hub.