DMVPN

Fryguy — Wed, 03 Aug 2011 12:53:03 +0000

So let me talk a moment and talk about DMVPN – Dynamic Multipoint VPN technology.
Currently I am working on a project to test the viability of a DMVPN network as well as help bring the team up to speed on this technology. Since I am doing that I figured it would be a good idea to share some of what I have learned with others – plus blogging it like this helps me to review the material at a later date. 🙄
So the first thing that probably should be answered – What is DMVPN? It is a solution for building a scalable IPsec VPN network utilizing the Internet (or other public network – say MPLS) for the WAN backbone. DMVPN takes advantage of another protocol, Next Hop Resolution Protocol (NHRP) and a Multipoint GRE tunnel interface. With NHRP the router will query the Next Hop Server (NHS) to find out a mapping for a network. Once it finds out the remote IP, the Multipoint GRE will build a dynamic tunnel between the two routers. It will then place that network in its NHRP mapping table.
DMVPN can provide a full-mesh topology with a simplified configuration. You only need to have all the spokes communicate with the hub initially, and then from there the spokes can learn the outside IP of the other routers and build dynamic tunnels when they need to communicate. What is nice with this is that if you add a new spoke to the network, there are neither changes on the hub nor any other spoke – only the new spoke needs to be configured.
What are some of the uses for DMVPN? Work at home workers, remote working locations via cellular, backup to a private WAN, and those are just to name a few. I am sure you can come up with some of you own based on your experiences. (continued)

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DMVPN