GRE over IPsec tunnels (Part 2)

In my last post I wrote about GRE over IPsec, but only with static routes. One of the benefits of GRE over IPsec tunnels is that you can send multicast traffic  over the tunnel. With a plain IPsec tunnel this is not possible. So to prove that multicast traffic can cross the GRE over IPsec tunnel I took the topology of my last post and removed the static routes from the configuration of the HQ and Branch routers.
Below the used topology:

Then configure the EIGRP configuration on both routers.

R1#sh run | se eigrp
router eigrp 10
no auto-summary

The syslog below confirms that the EIGRP adjacency is up and running:

Then use the “debug ip packet detail” command to verify that multicast is used and allowed:

To prove the solution is working check the routing table.

And that’s all there to configure dynamic routing over a GRE over IPsec tunnel.


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