A network typically includes a collection of routers interconnected with each other. Routers are commonly used at interfaces between local area networks (LANs) and wide area networks (WANs). When TCP/IP is used for data transmission between computer systems, the transmitted data is routed through intermediate routers. IP networks are implemented with routers that interconnect physically and logically separate network segments. The function of a router is to decide, for each data packet arriving at its input, which of the several adjacent routers it is to relay the data packet to. Typically, a router accomplishes this by examining a header associated with the data packet to determine that data packet's destination. A router uses a routing protocol to exchange information with other routers in order to maintain a consistent view of the network. The routers distinguish data packets according to network protocols and forwards traffic according to network-level addresses utilizing information that the routers exchange among themselves to find the best path between network segments. The router examines the destination address of the data packet, consults the router's memory to determine the router's current understanding of the network configuration, and then sends the data packet along to another router that will normally bring the data closer to the final destination address.

A router is a networking device having a defined number of physical communication interfaces (e.g., modems) under the control of one or more processors collectively executing a single control function. A typical router includes ports for channeling communication throughout the network, a primary port facility having a single processor, and a router card for controlling the router ports. Each router in a network is a device having an input side with at least one input connected to an adjacent router and an output side with several outputs, each of which is connected to an adjacent router. The router receives a data packet through its input and forwards the data packet to an adjacent router through one of its several outputs. A router includes a series of line cards in connection with a communication fabric. A routing table is initially downloaded to each line card along with configuration files. One of these files in particular, the dispatch table, is specifically constructed for suitability for use within a local routing switch processor in the line card.

Mobile stations, e.g., cellular phones, recently have become able to obtain wireless connections to packet data networks, such as the Internet. Wireless networks allow computing devices to share information and resources via wireless communications. Examples of computing devices include laptop or desktop computers, personal digital assistants (PDAs), mobile phones, data terminals, data collection devices, and other portable and non-portable computing devices. Cellular and other wireless networks have been connected to IP networks in order to allow cellular phones and other mobile devices to communicate with remote devices over the IP network. Wireless broadband networks make high performance Internet access possible where wired broadband infrastructure is impractical. A typical cellular network covers a contiguous area that is broken down into a series of cells. Each cell has a base station and may be subdivided into sectors. By using routers, the intelligence of the cellular network can be distributed to allow efficient processing of traffic and communication over the IP network.

Networks enable a plurality of nodes to communicate with each other. Nodes can include computers, servers, storage devices, mobile devices, PDAs, wireless telephones, etc. Networks can include the nodes themselves, a connecting medium (wired, wireless and/or a combination of wired and wireless), and network switching systems such as routers, hubs and/or switches. A mobile node is able to change its point of attachment from one network or subnet to another as it roams from its home network. The mobile node travels from link to link, maintaining ongoing communications by updating its care-of-address at each new link. Mobile IP is a protocol which allows laptop computers or other mobile nodes to roam between various sub-networks at various locations while maintaining internet and/or WAN connectivity. Without mobile IP or related protocol, a mobile node would be unable to stay connected while roaming through various sub-networks. This is because the IP address required for any node to communicate over the internet is location specific. Mobile routers eliminate the need for a host to be aware of mobility. The mobile router hides the IP roaming from its local nodes within the mobile network, so that the local nodes appear to be directly attached to their home network.

Routers are specialized computer networking devices that route or guide packets of digitized information throughout a network. Generally speaking, a data packet is a digitized and organized block of binary data that is a packaged portion of a specific communication or data transfer from a source location to an ultimate destination on a network. Common types of data packets routed, for example, over the Internet network and most commonly dealt with in data routing include transfer control protocol (TCP) packets and Internet protocol (IP) data packets. Packet forwarding in computer networks is generally accomplished using one of three available techniques: bridging, routing, or switching. Routing protocols permit routers to forward packets either as datagrams or as part of virtual circuits. In both approaches, routers build and maintain a routing table specifying the next hop to each destination. In a typical packet data router, packets originating from various source locations are received via a plurality of communication interfaces. The router reads the routing information of each received packet and, if it recognizes the information, forwards the packet to the appropriate communication interface for further transmission to its destination.

In cellular communications, a mobile switching center switches all traffic in the cellular network. A data interworking function provides connectivity from the mobile switching center to the Internet or other data network via circuit switched and packet switched data protocols. Each radio transceiver at a node in the wireless network comprises part of the infrastructure and can route data through the wireless mesh network to its destination just as in the wired Internet. The data traffic can be routed around obstructions rather than needing to deploy additional base stations for line-of-sight in densely populated diverse geographical locations. The more wireless routers are added to the network, the more robust and far-reaching the network becomes. Each wireless router can communicate with other nodes, i.e. other wireless routers in any direction. The "mobile ad hoc network" (MANET) is an autonomous system of mobile routers connected by wireless links. The routers are free to move randomly and organize themselves arbitrarily; thus, the network's wireless topology may change rapidly and unpredictably.

With the improvement of wireless network communication, technologies about routers are advanced greatly. Mobile routers enable entire networks to roam. For example, an airplane, car, train, or ship can travel around the world, while passengers stay connected to the Internet. Wireless routers generally comprise three components, a full TCP/IP (transmission control protocol/internet protocol) protocol suite support, a wireless operating system that optimizes the wireless network performance and robustness, and a high-performance digital RF modem. When mobile devices, such as PDAs, mobile phones, and laptop computers, are attached to an access point, the mobile devices' MAC (media access control) address is associated with an IP address from within the subnet router's IP address space. The router routes packets by determining an optimal path based on its current view of the network and forwards the packet across the network boundaries to a destination using the optimal path.