Cisco DMVPN configuration

Cisco DMVPN (Dynamic Multipoint Virtual Private Network) is a Cisco-proprietary solution that allows for the creation of a full mesh VPN (Virtual Private Network) among multiple sites using a single hub router. This allows for secure communication between sites without the need for a full mesh of point-to-point tunnels, reducing the overall configuration complexity.

Here is a general overview of the steps required to configure DMVPN:

Configure a routing protocol, such as EIGRP or OSPF, on all routers in the network. This allows the routers to share routing information and dynamically discover new VPN spoke sites.

Configure a Tunnel Interface on the hub router, which will act as the endpoint for the spoke-to-hub tunnel.

Configure NHRP (Next Hop Resolution Protocol) on the hub and spoke routers. NHRP is used to map the spoke routers’ public IP addresses to their private IP addresses, allowing for the spoke-to-hub tunnel to be established.

Configure the crypto map on the hub router to specify the IPSec parameters, such as encryption and authentication algorithms, for the VPN.

Apply the crypto map to the Tunnel Interface on the hub router, and configure the spoke routers to initiate the VPN connection to the hub.

Verify the VPN connection by checking the routing tables and the status of the IPSec SA (Security Association) on all routers.

It’s important to note that this is a very high-level overview, and there are many other configuration options and considerations depending on the specific needs of your network. Cisco’s website has various technical documents with more detailed information and example configurations, and it’s highly recommended to consult with a networking expert who has experience with Cisco DMVPN.