We are running GRE over IPSEC between location A and B. It has been observed that after some time the tunnels go in a hang state and the traffic does not pass through these tunnels.
It has been observed that the tunnels at this time are shown up. After rebooting the router; tunnels come out of a hang state and traffic continues to flow. Reinitialization of tunnel is of no help.
The routers in question is Cisco 3825 with location A c3825-advsecurityk9-mz.124-3e.bin IOS and location B c3825-advsecurityk9-mz.124-3d.bin