Hairpinning or U−turn
This feature is useful for VPN traffic that enters an interface but is then routed out of that same interface. For example, if you have a hub−and−spoke VPN network, where the security appliance is the hub, and the remote VPN networks are spokes, in order for one spoke to communicate with another spoke, traffic must go into the security appliance and then out again to the other spoke.
Use the same−security−traffic command to allow traffic to enter and exit the same interface.
securityappliance(config)#
same−security−traffic permit intra−interface
Note: Hairpinning or U−turn is applicable for VPN Client to VPN Client communication, as well.