Another Big Picture post: overview of DMVPN Phase I:
To understand the principles of DMVPN Phase I, remember these facts:
- Spokes use point-to-point GRE tunnels;
- Hub site has multipoint GRE tunnel;
- All the traffic flows through the hub site;
- The next-hop for routes received over DMVPN must be the hub site;
- NHRP is used by the hub site to get spokes’ tunnel endpoint addresses.
- Spoke sites use NHRP just to register with the hub site.
Choose the Optimal VPN Service webinar describes the principles of DMVPN, usage guidelines and high-reliability designs. DMVPN: Advanced and Crazy Scenarios has detailed configurations for basic setups and some pretty advanced designs.
Before Petr accuses me of beating a dead horse, let me mention that he wrote an excellent blog post describing the intricate details of DMVPN Phase I. If you’re attending my DMVPN: Advanced and Crazy Scenarios webinar, I would recommend you read that post first.