DMVPN

In my opinion, Dynamic Multipoint VPN (DMVPN) is the greatest technology that Cisco has implemented. It has numerous advantages over "traditional" VPN technologies:

• Simple deployment
• Can be used over any medium (3G/4g, cable, DSL, fibre, etc)
• Scalable, with no additional configuration required on the hub to accommodate growth
• No need to update the configuration on the hub as sites are added, removed, or changed
• Spokes can have static or dynamic IPs. It will even work through NAT.
• High availability is easy to configure
• Spokes can communicate with each other directly, without passing through the hub. This can improve spoke-to-spoke performance and minimize the load on the hub.
• Natively uses standard routing protocols (OSPF, BGP, EIGRP, etc)
• Can easily be configured as a backup connection, as it supports routing protocols and automatically sets a high metric.
• Can support multiple network technologies, such as IPv6, multicast, and L2TP tunnels
• Can be easily integrated into customer IPVPNs in a service provider environment