add a new transport method so that when a node is marked as dead, we

add a new transport method so that when a node is marked as dead, we
shut down and restart the transport

othervise, if we use the tcp transport the tcp connection might try to
retransmit the queued data during the time the node is unavailable.
this together with the exponential backoff for tcp means that the tcp
connection quickly reaches the maximum backoff rto which is often 60 or
120 seconds.   this would mean that it could take up to 60/120 seconds
before the tcp layer detects that the connection is dead and it has to
be reestablished.