Dynamic Multipoint Virtual Private Network (DMVPN) is a dynamic tunneling form of a virtual private network (VPN), using a multi spoke-to-hub network in which the network addresses of the spoke routers do not need to be known, and therefore do not need to be configured in the hub router.
One advantage to this form of VPN is a scalable network in which the size of the hub configuration is minimized. When one spoke of the network needs to send traffic to another spoke, a direct transfer is possible without having to add any load onto the hub. This is achieved by the creation of a dynamic GRE tunnel directly to the other spoke. The network address of the target spoke is resolved with the use of Next Hop Resolution Protocol (NHRP).
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