DMVPN

As explained in Acing the CCNA Exam: Volume 2 Advanced Networking and Security

DMVPN is a Cisco technology that dynamically establishes multipoint VPN tunnels between routers, commonly forming a full mesh from a hub-and-spoke configuration.

DMVPN is a Cisco technology that reduces the effort of building interconnected site-to-site VPNs. Instead of manually configuring tunnels between every pair of routers, you configure a hub-and-spoke topology; DMVPN then facilitates a full mesh of tunnels between routers. section 16.3.1 section 16.4

Key operational facts:

• The hub distributes information to each spoke, allowing spokes to form tunnels with one another without manually configuring every tunnel. section 16.3.1
• DMVPN uses unencrypted GRE tunnels by default; GRE supports varied traffic, but unencrypted tunnels are not secure. section 16.3.1 section 16.4
• IPsec is recommended when VPN traffic crosses the internet, producing encrypted tunnels while DMVPN supplies the dynamic full-mesh behavior. section 16.3.1
• A full mesh improves direct connectivity between locations, while manual configuration becomes labor intensive and increasingly prone to errors as sites are added. section 16.3.1 section 16.4

Figure 16.18 DMVPN automatically creates a full mesh of IPsec tunnels after configuring a hub-and-spoke topology.

Use the figure to visualize how configuring a hub-and-spoke topology results in a full mesh of IPsec tunnels. section 16.3.1

How Acing the CCNA Exam: Volume 2 Advanced Networking and Security covers it

How deep it goes

Explains hub distribution, full-mesh formation, and GRE/IPsec defaults but stops short of detailed configuration commands.

Examples

Uses a hub-and-spoke configuration that automatically produces a full mesh of IPsec tunnels as the central example.

What you can do after

Apply DMVPN by recognizing when a hub-and-spoke setup should dynamically provide full-mesh connectivity.

How it connects

Connects hub-and-spoke and full-mesh topologies with GRE, IPsec, and site-to-site VPNs.

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Related concepts

• star topologyuses · A star topology is a network arrangement in which multiple peripheral nodes connect and communicate through a central hub or node.
• full mesh topologyproduces · A full mesh topology is a network arrangement in which every node has a direct connection to every other node.

This explainer was generated by Manning's knowledge graph from the text of Acing the CCNA Exam: Volume 2 Advanced Networking and Security. The section links point to the parts of the book it draws on.