From the point of view of a router configured with NAT, there is only inside and outside. Usually the _inside interface of a router is where the traffic flows in (from the private network). And the _outside interface of a router is where the traffic flows out of the network (to the Internet). The _ip nat inside interface subcommand classifies an interface as the inside interface. The _ip nat outside interface subcommand classifies an interface as the outside interface. - - - - - - - -/(ip nat outside global) and (ip nat inside local) are invalid configuration commands