How to create a mesh VPN network using Tunnel Interfaces and OSPF

It is quite easy to implement a Hub and Spoke VPN network using both Tunnel Interface and OSPF but the transition to a mesh network can be troublesome if you want to redistribute the SonicWall’s firewalled subnets.

In figure 1, you can see that a route exist to the second spoke (#6). In Figure 2, it should the equivalent on Spoke 2 (route #6).

The solution in to create a fully mesh environment is to use the OSPF “Passive” mode on the connected interface of all the mesh network’s nodes.

When OSPF passive mode is enabled on an interface, neither OSPF packets are sent nor any received on this interface. It only results in that interface’s network being advertised by OSPF to other OSPF peers as LSA 1 (Router) instead of LSA5 (External) when using “Redistribute Connected Networks”.

To Activate the Passive mode on your SonicWall’s internal networks, simply go to Network, Routing.

Then configure an internal network