Image Number 11 for United States Patent #7908481.
A communications system includes a first network that includes a plurality of entities and a router. The router includes a network address translator. A node is capable of communicating data units with entities in the first network. Each data unit includes security information, such as information according to the Internet Security Association and Key Management protocol (ISAKMP) and the Encapsulating Security Payload (ESP) protocol. The network address translator is adapted to convert a destination address in a received data unit from the node to an address of one of the entities based on the security information in the received data unit.