Continuing the review of the TSHOOT Topology, on the IPv6 network map there is a GRE tunnel that is configured between Router 3 and Router 4. This tunnel is in place to allow IPv6 traffic to traverse the 10.1.1.8/30 IPv4 network. So, while reviewing the IPv6 tshoot topology, I decided to try out the tunnel configuration.
There are several ways to configure tunnels to allow IPv6 traffic to traverse IPv4 networks (and vice versa). This post will be focusing on a GRE tunnel configuration. If you want to review the other ways to create tunnels, i.e. Automatic IPv4-Compatible IPv6 Tunnels, IPv6 Rapid Deployment Tunnels, and Automatic 6to4 Tunnels, I've included a link below to a great resource on Cisco's website that shows some great examples of other tunnels.
I threw together the following network diagram to provide a visual of what we are configuring: