VPN

I have several remote sites that connect back to my datacenter for support purposes.  The tunnels drop within minutes if there is no traffic and can only be reestablished from the remote side.  A simple "ping" from a PC on the remote network to the datacenter is all that is required to make that reconnection, but is not practical.  I can not ask the client to preform the ping before I can connect and I can't place a "dummy" PC on the network to continuously ping the datacenter.

The remote sites are running ver1.32 and the datacenter is currently ver1.235, but I intend to upgrade to 1.32.  Am I overlooking the setting to preform a "keep alive" like function?  What are my options?


Thanks.