GRE over IPsec tunnels (Part 2)
20/02/2015 Leave a comment
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
network 10.10.10.0 0.0.0.255
network 172.18.2.0 0.0.0.255
no auto-summary
R1#
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.
