Im having issues with a GRE Tunnel interface dropping, we have two central site VPN routers in different DC's, the remote site router has a GRE tunnel to each central site route running OSPF across the tunnels.
The MTU are set the same on all tunnels and we have checked the ISP doesn't have issues. The link to the internet from the remote site is 100MB and the central site is 1GB.
When pushing 30MB of traffic to the primary tunnel interface there is a high amount of packet loss, but if we do this in parallel with 30MB to the public interface on the router there is no packet loss.
Could you point me in the direction of a good troubleshooting document