basic OE test, using road and east triggered by packet using NETKEY on road.
road has short ikelifetime << salifetime,  and no traffic after the ping. 
The rekeymargin is also relatively short O(20) seconds.
IKE SA will expire, when it will expire will check if IPSEC was recently used,
if not delete parent/IKE and child/IPSEC SA.

New ping will initiate a new IKE negotiation and setup a new IPSEC SA.