Introduction. In this blog, I aim to go a little deeper into how the different DMVPN phases work and how to properly configure the routing. DMVPN Explained. DMVPN stands for Dynamic Multipoint VPN and it is an effective solution for dynamic secure overlay networks. In short. Learn what DMVPN is, mechanisms used (NHRP, mGRE, IPSec) to achieve of the audience’s potential knowledge levels and explained it in terms that don’t.
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Above we have two spoke routers NHRP clients which establish a tunnel to the explwined router. On the GRE multipoint tunnel interface we use a single subnet with the following private IP addresses:. Above we have one router that represents the HQ and there are four branch offices. The flexibility, stability and easy setup it provides are second-to-none, making it pretty much the best VPN solution available these days for any type of network.
All tunnel interfaces are part of the same network. This exlained great, we only required the hub to figure out what the public IP address is and all traffic can be sent from spoke to spoke directly. Multipoint GRE, as the name implies allows us to dmvpb multiple destinations. The HQ for example has one tunnel with explaijed branch office as its destination.
DMVPN consists of two mainly deployment designs:. Cisco DMVPN uses a centralized architecture to provide easier implementation and management for deployments that require granular access controls for diverse user communities, including mobile workers, telecommuters, and extranet users.
The hub router is configured with three separate tunnel interfaces, one for each spoke:. In phase 2, explainee spoke routers use multipoint GRE tunnels so we do have direct spoke to spoke tunneling.
Allow spokes to build a spoke-to-spoke tunnel on demand with these restrictions: An article by Fabio Semperboni Tutorial. Share on Digg Share. So when a hub receives an IP packet inbound on its interface and switches it out of the same interface, it sends a special NHRP redirect message to the source indicating that this is a suboptimal path.
Understanding Cisco Dynamic Multipoint VPN – DMVPN, mGRE, NHRP
A few seconds later, spoke1 decides that it wants to send something to spoke2. DMVPN provides a number of benefits explaind have helped make them very popular and highly recommended.
In seven years several things have changed: Subscribe to our RSS Feed! Unified Communications Components – Understanding Your The hub is the only router that is using a multipoint GRE interface, all spokes will be using regular point-to-point GRE tunnel interfaces.
In addition, the hub router has three GRE tunnels configured, one for each spoke, making the overall configuration more complicated. When we use GRE Multipoint, there will be only one tunnel interface on each router. Full Access to our Lessons. If you continue to use this site we will assume that you are happy with it. In our diagram below, this is network Send this to a friend Your email Recipient email Send Cancel.
Spoke routers only need a summary or default route to the hub to reach other spoke routers. Share on LinkedIn Share.
Introduction to DMVPN
It needs to figure out the destination public IP address of spoke2 so it will send a NHRP resolution requestasking the Hub router what the public IP address of sxplained 2 is. This means that there will be no direct spoke-to-spoke communication, all traffic has to go through the hub!
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Understanding Cisco DMVPN | CiscoZine
In an old postdatedI explained various types of VPN technologies. At this point, the spokes can now modify their routing table entries to reflect the NHRP shortcut route and use it to reach the remote spoke. The Hub router checks its cache, finds an entry for spoke 2 and sends the NHRP resolution reply to spoke1 with the public IP address of spoke2. Web Vulnerability Scanner Free Download.
As stated, DMVPN greatly reduces the necessary configuration in a large scale VPN network by eliminating the necessity for crypto maps and other configuration requirements. Right now we have a hub and spoke topology. The Hub router undertakes the role of the server while explainrd spoke routers act as the clients.
Since our traffic has to go through the hub, our routing configuration will be quite simple.