1. A method comprising: determining an ingress security zone associated with an ingress of a first network device based on a first key and a media access control (MAC) address of a source of a packet; determining an egress security zone of a second network device based on a MAC address of a destination for the packet and a second key; performing a policy lookup based on the ingress security zone and the egress security zone to identify a policy to apply to the packet; and applying the policy to the packet.