Packets are transmitted on the physical link. Then, devices like Ethernet switches or IP routers can forward the packets toward their destination, which might be a different zone on the same machine as the sender.
For virtual links, the packet is first sent to a virtual switch. If the destination link is over the same device, such as a VNIC on the same physical link or etherstub, the packet will go directly to the destination VNIC. Otherwise, the packet will go out the physical link underlying the VNIC.
For information on features that can be used in an exclusive-IP non-global zone, see Exclusive-IP Non-Global Zones in Introduction to Oracle Solaris Zones .