Major Description
In case of disconnect we only send disconnect GR command to GR but the socket(s) between TUNNEL and GR remain(s) open. In case of a new connect on the same channel we create a new RouterStubManager and thus a new socket from TUNNEL to GR while the old one remains open and connected. Not good!
In TUNNEL#handleDownEvent right before a new TUNNELStubManager is created we should destroy previous TUNNELStubManager if it is non null.
