A router includes a routing table containing flags each representing a public-network side or a LAN side. A path for a received packet is determined such that the packet is forwarded to the next node through the LAN according to the next node address when the flag corresponding to the specified...http://www.google.com/patents/US5802316?utm_source=gb-gplus-sharePatent US5802316 - Routers connecting LANs through public network
