I have found that in our GRE DSL environment, client workstations cannot perform a ping or a traceroute from their dos prompts to internal Domain controller servers going over a GRE tunnel. The resources are availabe to them, however they cannot run the ping. Clients receive an "unresponsive" message. I have verified that there are no ACL's blocking the ICMP request. Wanted to know if anyone else out there may be experiencing this. Thanks.
I have this problem too.