Generally, Port Address Translation (PAT) is a feature of a network device (e.g., router) that translates network communications.  In particular, Port Address Translation may operate on a router to connect two networks together.  One of these networks is addressed with either private or obsolete addresses that need to be converted into legal addresses before packets are forwarded onto the other network.  Port Address Translation can be used in firewall systems to hide addresses of clients or in multi-port broadband network access devices (e.g., Digital Subscriber Line, routers, cable modems, and other network access devices) such that a single address can be used by many clients on a network. 
Port Address Translation uses a port-bundle host key (PBHK) to uniquely identify each client associated with a host.  To derive the port-bundle host key, a portal may use the source port of an incoming Hypertext Transport Protocol (HTTP) message and apply a complex formula to the HTTP message from the source port.  The encoding/decoding to derive the port-bundle host key must be done for every packet.  Accordingly, such encoding/decoding operations for all packets are computationally intensive and therefore, make a network system difficult to scale.