CA2332023A1 - Nomadic translator or router - Google Patents

Abstract

A nomadic router or translator (10) enables a laptop computer or other portable terminal (12) which is configured to be connected to a home network to be connected to any location on the Internet or other digital data communication system (14). The router (10) automatically and transparently re-configures the terminal (12) to its new location and processes outgoing and incoming data. The router (10) includes a processor (11) which appears as the home network to the terminal (12), and appears as the terminal (12) to the communication system (14). The terminal (12) has a permanent address, the router (10) has a router or translator address, and the terminal (12) transmits outgoing data to the system (14) including the permanent address as a source address. The processor (11) translates the outgoing data by replacing the permanent address with the router address as the source address. The terminal (12) receives incoming data from the system (14) including the router address as a destination address, and the processor (11) translates the incoming data by replacing the router address with the permanent address as the destination address. Alternatively, the terminal (12) can be directly connected to a point on a local network (14), and the router (10) connected to another point on the network (14). The router (10) can be employed to implement numerous applications including nomadic e-mail, network file synchronizer, database synchronizer, instant network, nomadic Internet and trade show router and can also be utilized as a fixed nomadic router.

Description

WO 99146$90 PCT/US99/05260 NOMADIC TRANSLATOR OR ROUTER
Technical Field The present invention generally relates to the art of digital communications, and more specifically to a portable translator or muter which enables a user digital communication terminal to be location and device transparent.
Backeround Art User digital communication addresses such as Internet or IP addresses are conventionally associated with a fixed physical location, such as a user's business telephone line.
However, portable communiication devices such as laptop computers are becoming increasingly popular, and it is common for a user to access the Internet from Locations as diverse as hotel rooms and airplanes.
Digital communication networks are set up to route communications addressed to a communication I5 address to the associated physical Location. Thus, if a laptop connputer is connected to a remote location, communications to and from the computer will not be associated with the user's communication address.
In order for a computer (lhost) to communicate across a network (e.g., the Internet), softvwareprotocols {e.g., Transport Control Protocol/Internet Protocol (TCP/IP)) must be loaded inta the host. A host computer sends information {i.e., packets of data) to devices on the network (roisters) which receive the packet's and send the packets back to the destination host.
The destination host will route replies hack using a similar process. Each host computer and roister must be configured so it will know who to send the packets of data t:o. A' roister will receive the packets only if the host computers specifically send (address) the packets to that rou~ter.
If a host is configured incorrectly (bad address), then the host computer and roister will be unable to commiuiicate.
With the advent of mobile computers (laptops) and the desire to plug them into various networks to gain access to the resources on the network and Internet, a mobile computer must be configured for each network it plugs into. Traditionally this new configuration can be done either (i) manually in software on the mobile computer (usually causing the mobile computer to be restarted to load iin the new configuration), or (ii) with a new set of protocols which must be utilized on the mobile computer to obtain the configuration infonuation from a device on the network to which the computer is being connected. When new services (protocols) are created to add functionality to the host computers, these new protocols must be; updated in the host computers or roisters, depending upon the type of new functionality being added.

WO 99/46$90 PCT/U599/05260 DISCLOSURE OF INVENTION
In accordance with the present invention, a portable "Nomadic" muter or translator enables a laptop computer or other portable terminal which is configured to be connected to a local home network to be connected to any location on the Internet or other digital data communication system.
The nomadic router automatically and transparently re-configures the terminal to its new location and processes outgoing and incoming; data.
The nomadic router includes a processor which appears. as the home network to the; terminal, and appears as the terminal to the communication system. The terminal has a permanent address, the nomadic muter has a router address, and the termini transmits outgoing data to the system including the permanent address as a source address. The processor translates the outgoing data by replacing the permanent address with the router address as the source address. The tE;rminal receives incoming data front the system including the router address as a destination address, and the processor translates the incoming data by replacing the router address with the permanent address as the destination address.
The terminal can be directly connected to a point on a local network, and the nomadic router connected to another point on the network. The nomadic router can be employed to implement numerous applications including nomadic e-mail, network file synchronizer, database synchronizer, instant network, nomadic Internet, mobile virtual private network and trade show router, and cw also be utilized as a fixed nomadic router.
The nomadic router can be implemented as software and/or hardware. The nomadic rnwter establishes location and device transparency for a digital communication terminail such as a laptop computer. The terminal can be connected to any of a variety of networks and locations which can employ a variety of communication interface devices.
The nomadic muter automatically converts the actual location address to a unique communication address for the user such as an Internet address, such that the terminal ;performs communications originating from the communication address regardless of the physical location of the terminal.
The nomadic router also automatically configures the terminal to utilize a selected one of the interface devices, and switches from one to another if the first device malfunctions or becomes otherwise ~mavailable.
The nomadic router includes software and services which can be packaged in a personal portable device to support a rich set of computing and communications capabilities and services to accommodate the mobility of nomads (users) in a transparent, integrated, and convenient form.
This is accomplished by providing device transparency and location transparency to the user.
There is a vast array of communication device alternatives such as Ethernet, Wireless LEAN, and dialup modem among which the users switches when in the office, moving around the office, or on the road {such as at a hotel, airport, or home). The device transparency in the nomadic :router provides seamless switching among these devices (easily, transparently, intelligently, and without session loss.
The location transparency support in the nomadic router prevents users from having to reconfigure (e.g., IP and gateway address) their network device (laptop} each time they move to a new network or subnetwork.
The present nomadic muter provides a separation of location and identity by providing a permanent IF address to the network device (host). The nomadic router provides independence between. the location,

-2-communication device, and the host operating system. There are no new standards need to be adopted by the networking community. All specialized processing is stored internally to the nomadic routes with standard interfaces to the host device and various communication devices.
The nomadic routes supports the migration to Network Ca~mputers by providing identity and security services far the user. The nomadic: routes also supports multiple parallel communication paths across the communications network for soft h4mdoff, increased throughput, and fault tolerance by suppo~cting multiple communication substrates.
A portable routes for enabling a data communication terminal to be location and device transparent according to the present invention, comprises: a first module for storing a digital communication address of a user;
a second module for detecting a data communication network location to which the terminal is comaected; a third module for detecting communication devices that are connected to the terminal;
a fourth module far establishing data communication between the terminal and the network such that the communication address of the location from the second module is automatically converted to the communication address of the user ;from the first module; and a fifth module for automatically selecting a commurucati.on device which was detected by the third module for use by the fourth module.
The present nomadic routes utilizes a unique process embodied in a self contained apparatus which manipulates the packets of data being sent between the host computc;rs and routers. This process provides an intelligent active universal translation of the content of the packets being-transmitted between the host computer and nomadic muter. The translation allows the host computer to communicate with the nomadi'.c routes even when the host computer is not configured to communicate with the nomadic routes.
This is achieved by the nomadic routes pretending to be the routes which the host is configured for, and by the nomadic muter pretending to be the host which the routes expects to communicate witlh. Therefore, the nomadic routes supports the mobility of computers in that it enables these computers to plug into the network at different locations {location independence) without having to install, configure, or utilize any new protocols an the mobile computer.
The mobile computer continues to operate without being aware of the change in location or new configuration, and the nomadic routes translates the data allowing the lhost to think that it is communicating with the routes. By putting this process in a self contained apparatus, the deployment of new protocols can be performed independently of the host computer and its operating system (host independent).
All specialized processing and translation is stored intenlally in the nomadic routes with standard interfaces to the host device and various communication devices. Thus, no new standards need be adopted. By removing tile complexity of supparting different network environments out of the mobile compute- and into this self-contained apparatus, the nomadic routes allows the host computer to maintain a very minimal set of software protocols and functionality (e.g., the minimum functionality typically installed in network computers) to communicate across the network.
The nomadic routes translation ability also enables the usc; of alternate communication paths (device independence) without the host computer being aware of any new communication device that utilizes an alternate

-3 -WO 99/46890 PCT/US99/052bt1 communication path. The translation of the packets is done not just at the physical, link, or network layer of the protocol stack but at the transport au~d application layers as well. This allows the network card,. protocol stack, and application running on the hosl. computer to be independent of the network environment and configuration.
As an example of the communication device independence, the translation allows soft handoff, increased throughput, and fault tolerance by supporting multiple communication substrates. In addition, the nomadic router translation ability provides a flexible process for deploying enhanced nomadic and mobile computing software and services such as filtering of packets and determining which packets should be allowed to be transmitted between the mobile computer and the nomadic router or local area network (Internal Firewall}.
The muter apparatus can be: (i) carried with the mobile u~.ser (e.g., using an external box); (ii) attached to the mobile computer (e.g.; PCMCIA card); (iii) installed inside the. mobile computer (e.g., a chip in the laptop);
(iv) or installed into the network infrastructure so it will already be there when the mobile computer user arrives (e.g., a box which plugs into the local area network translating packets being sent between the host and nomadic router, or a chip which is installed in routers on the network). The nomadic muter can also be provided in the form of software which is loaded into and run in the mobile computer or another computer or routf;r on a network.
These and other features and advantages of the present invention will be apparent to those skilled in the art from the following detailed description, taken together with the accompanying drawings, in which Iike reference numerals refer to like parts.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a diagram illustrating the implementation of the present nomadic router bE;tween the host computing device and various communication devices through standard interfaces;
FIG. 2 is a diagram illustrating the basic nomadic router architecture, which is rei:en;ed to as the hardware implementation architecrixre;
FIG. 3 is a flowchart illustrating a configuration overvic;w of the basic steps performed when a host device is attached to the present nomadic tauter and when a network interface is attached to the tauter;
FIG. 4 is a flowchart illustrating the router's automatic adaptation to the host devicf; when the first data packet from the host is sent to the attached muter or when an <~ctivation interrupt or signal is received;
FIG. 5 is a flowchart illustrating the process by which the router initializes and checks the various communication device interfaces for initialization, activation, ete.;
FIG. 6 is a diagram illustrating the basic nomadic roister architecture when implemented as software in the host device;
FIGS. 7a to 7g are diagrams illustrating protocol stack implementations for various nftwork devices, and the translation function happening at all layers of the protocol stack in the nomadic roister;
FIG. 8 is a flowchart illustrating the nomadic router',s proxy ARP packet interception and host reconfiguration process;
FIGs. 9a and 9b in combination constitute a flowchart illustrating the nomadic router's translation process which takes place in the host computer and nomadic muter at various levels in the protocol stack;

-4-WO 99/46890 PCT/Ua99/45260 FIG. 10 is a diagram illustrating the architecture of the nomadic router implemented as a hardware device including a microcontroller arid a non volatile memory for storing algorithms implementing; the translation function;
FIG. 11 is a diagram illustrating the architecture of the nomadic router apparatus imp~Iemented as an Application Specific Integrated Circuit (ASIC) chip;
FIGS. 12a to 12d are diagrams illustrating host and network interface modes in which the nomadic muter is able to operate;
FIG. 13 is a simplified perspective view illustrating the nomadic router as implemented in a self contained box which connects onto a local area network via a network interface port and has multiple ports to connect to host computers;
FIG. 14 is a simplified perspectiveview illustrating the nomadic muter apparatus as implemented on a PCMCIA Type III card where the nomadic router plugs into the host computer's type II slot and the communication card device, of Type II, plugs directly into the nomadic muter so both may be powered and stored in the portable host computer; and F1G. 15 is a simplifiedperspectiveview illustrating the nomadic muter as implementedl on a PCMCIA
Type Ii card where the nomadic router plugs into the host computer via a type II interface slot and where the communication card device, Type II, plugs into the nomadic muter type II card.
MODES) FOR CARRYING OUT 'THE INVENTION
BASIC NOMADIC ROUT:ER
WeII-defined Standard Interfaces:
FIG. 1 illustrates a "Nomadic" translator or router 10 embodying the present invention as being connectedbetween a host device or computer 12 and a communications device 14.
The host device 12 is a laptop computer or other fixed or mobile digital data communication ter~rnirlal which is sufficiently portable or mobile that it can be earned from one ioc:ation or another. A laptop computer, for example, can be used in any convenient location such as an airplane, customer's office, home, etc.
The communications device 14 can be part of any type of communication system to which the host computer 12 can be connected. Such communication systems include., but are not limited to, local networks, wide area networks, dial-up and direct Internet connections, etc. In a typical application, the eommunilcations device will connect the host computer to a local network which itself is connected to the Internet. Thus, the host device 12 is able to communicate with an unlimited number of networks and nodes which are themselves interconnected with routers, switches, bridges, etc. in any known manner.
The present router 10 includes a terminal interface 10a which normally is used to connect the router 1(1 to the host device 12, and a system interface 10b which connects the router 10 to the communications device 14. As will be further described below, the router 10 generally includes a processor consisting of h:~rdware and/or

-5-WO 99/46890 PCT/U:~99/05260 software which implements the required functionality. The router 10 is further configured to operate in an alternate mode in which the host device 12 is connected directly to a network, and the router 10 is also connected to a point in the network via the system interface 10b. In this case, the terminal interface l0as is unused.
Although the device 10 is described herein as being a roofer, it will be understood that; the router 10 is not a conventional router in that it includes the capability for providing interconnectabilitybetween networks.
Instead, the present router 10 is essentially a translator which enables the host device 12 to be automatically and transparently connected to any communications device 14, and process incoming and outgoing data for the device 12.
The host device 12 is provided with a permanent Internet .address which is convenientl;,y not changed in accordance with the present invention. The device 12 is also initially configured to communicate with a particular gateway or other home device at its base location. The gateway has a home address whiich the device I2 attempts to locate when it is connectedto any communication system. Without the functionality of the present nomadic router 10, the host device 12 would not be able to operate at at remote location because it would not find its gateway.
It will be understood that the term "home" does not relate to a residence, but is the netvwork, gateway or other communication device or system to which the terminal is nonmally connected and which corresponds to the home Internet or 1P address.
FIG. 1 further illustrates a top protocol layer 16 representing the host computing device 12 which generates and consumes data that is transferred through the communications device 14. This interface 16 is done just below the 1P Layer, and above the link layer in the typical OSI/ISO~
model. In the middle is a layer 1 & which represents the router 10 and whose fun ction it is to adaptively configure and utilize the underlying communications device and provide the router support described herein. A lower layer 20 is a physical communication which carnes out the communication (potentially wire-lined Internet based, ad hoc or wireless) as made available and determined for use by the nomadic roofer or user. Between the roui:er layer 18 and the layers 16 and 20 are interfaces 22 and 24 which the router 10 identifies and configures dynamically.
The present muter operates with host computers, routers, and other network devices through well-defined standard interfaces such as specified by the lETF (Intelxiet Engineering Task Force;) and IEEE
standardization committees. These s~~tandards specify the packet forn~at, content, and physical communication characteristics. As shown in FIG. 7a, host computers have to be conFgored at various layers of the protocol stack depending on the communication capabilities and configuration of the; current network being attached to.
Hubs, as shown in FIG. %b, provide a well defined interface to connect host computers and network devices by transmitting packets across multiple physical connections. Hubs do not provide any manipulate or translation of the content of the packets being transmitted.
Bridges or switches, as shown in FIG. 7c, provide an intelligent filtering mechanism by which they only transmit packets across multiple physical connection based upon. which physical connection the device is connected to, acc~rding to the link layer addressing (Media Access Control Address). Bridges amd switches do not manipulate the content of the packet and do not provide any higher layer protocol functionality.

-6-WO 99/46890 PCT/U:599/05260 Roisters, as shown in FI(J. 7d, accept packets based upon the destination address at the network layer in the packet. The host computer must explicitly address the packet. at the link Iayer to the roister. The roister will then retransmit the packet across the correct physical connection based upon how it is configured. No modification or translation of the packet is performed at any layer o:F the protocol stack other th2un the network layer.
Firewalls, as shown in FAG. '7e, filter packets at the network and transport layers to only allow certain packets to be retransmitted on to the other physical connection. Fire,walls do not manipulate the content of the packet, only forward it on to the next hop in the network if it passes the transport {port) or network (IP address) filter.
Proxys and gateways, as show in FIG. 7f, only receivepackets explicitly addressed to them by host computers. They only manipulate packets at the application level. 'Ihe present nomadic muter 10, as shown in FIG. 7g, manipulates the content of the packets at the Iink, network, transport, and application layers of the protocol stack to provide a translation between how the host computer is configured and the configuration of the network the host computer is currently attached to.
Unlike all other devices shown in FIGS. 7a to 7f, the :roister i0 will automatically intercept and translate packets without the other devices being aware of the roister 10 or have to be co~gured to use it. The translation algorithms in the roister 10 which provide this location independence are provided completely internal to the muter 10. Thus no new standards need to be developed, accepted, or implemented in host computers 12 or roisters 26 to deploy new network services when using the nomadic roister.
Whenever a new or different communication device (whi.ch includes the Iink and physical Iayers) is utilized in a host computer 12, the host computer's network layer nnust be aware of this new communication device. Since the roister 10 has it's own network interface to the comnnunication device, alternate communication devices can be utilized in the muter lU which the host computer 12 can utilizebut does not have to be configured to use.
Permanent Addressing not Location Based Today we communicatewith individuals in terms of the location of their communications instruments (for instance, their computer's IP address or their fax machine's phone number). In order to support mobility and changing communication environments and devices, it is necessary to create an environment where people communicate with other people, and not specifically with the devices they use.
To transparently support mobility and adaptivity in a wireless, potentially ad-hoc, communication internetwork, a common virtual nevtwork must be provided by an intelligent device or agent which supports the various computing hosts and communication devices.
The present nomadic roister 10 provides the mapping between the location based IP address used in the Internet today and the permanent user based address housed in the host CPU
in the device I2. This is illustrated in FIG. 2 as "IP Mapping". This mapping is done without support or knowledge of such mapping by the host CPU or user.

WO 99/46890 PCTN;~99/05260 The Internet RFC 2002 Mobile 1P protocol specifiesthe :mapping betweenpermanent and temporary IP addresses. The unique aspect of tlhe nomadic router is that the Motnile IP
protocols are not necessarily running in, or supported by, the host CPU but rather are internal to the nomadic muter. The host: configuration information such as its IP number are discovered or determined as illustrated in FIG. 4 and stored in the nomadic router 10 as illustrated in FIG. 2 as "Host Info." This configuration process is overviewed in FI:G. 3.
Optional Off-loaded Processing As illustrated in FIG. 2., the nomadic muter 10 can prow de off load communication processing for the host CPU by being physically separate from the host device 12. 'lf'he adaptation, selection, and transportation of information across the network is performed by the nomadic muter 10. This allows the host terminal or device 12 to utilize the network without having to directly support the network protocols. By having the nomadic muter be responsible for adapting to the current network substrate, the host CPU can maintain a higher performance by not having to run the routing, adaptation, packetization, etc. algorithms or packet processing.
The nomadic router can also queue, transmit, and receive data independent of whether or not the host device i2 is available or even attached. The CPU 11 built into thE; nomadic router 10 provides all necessary computing routines to be a fully functional network co processor independent of the host CPU. '.Chis will allow increased battery for the user since the nomadic muter does not have numerous user I/O devices as does the host device 12.
Location Independence The instant network nomadic router provides the ability to provide ubiquitous and reliable support in a location independent fashion. This removes any burden on tl!~e user for device reconfigw:ation (e.g., IP
address configuration, gateway or next hop router address, netmask, link level parameters, and security permissions) or data transmission.
The problem with existing protocol stacks is that comnnunicating devices have to be reconfigured every time the communication environment changes. TCP/1P require:. a new network, node and gateway number.
Appletalk will automatically choose an unused node number and discover the network number, but all open communications are lost and services have to be restarted to begin using the new information.
This occurs, for example, when a PowerBook is plugged into a network, put to sleep, and then powered up in a different network. All network services are restarted upon wakeup, and network applications get confused if they are not restarted. '.Che nomadic muter salves this problem by providing temporary as well as permanent network and node numbers similar to that provided by Mobile IP.
However, the nomadic router will also work with other protocol stacks (e.g., AppleTalk).
Mobile IP provides location independenceat the network Ievel and not at the link level, All link level parameters, which are device speciiuc, will be automatically configured as illustrated in FIG. :5 when a new communications (network interface) device is attached to the nomadlic router.
The nomadic router completely eliminates the need for manual configuration by adaptively supporting device independence.
_g_ WO 99/46890 PCT/EJE>99l05260 Multiple Substrates (Device Independence Another innovative feature of the nomadic roofer is the support for simultaneous use of multiple communication substrates. This is illustrated in FIG. 2 as "Device Selfection". Users should be abie to utilize two or more communication substrates, either to increase throughput or to provide soft-handoff capability. This functionality is not supported in today's typical protocol stacks (e.g., TCP/IP or AppleTalk).
For example, via the "network" control panel, the user can selectbetween communications substrates such as EtherTalk, LocalTalk, Wireless, ARA, etc., but cannot remotely login across EtherTalk while tryng to print via LocalTalk. Roisters are typically able to bridge together various communication substrates, but merging the LocalTalk and EtherTalk networks together is often not desirable for many reasons, including performance and security.
A problem with existing roisters today is that they require manual configuration and exist external to the node. To overcome this, the nomadic roister can support automatic configuration and full routc;r functionality internally. This allows a mobile or nomadic node to adapt to va~;ious communication and network devices dynamically, such as when the user plugs in a PCMCIA card or attaches a communications device to the serial port.
Once the nomadic routes becomes aware of the available communication devices and activates them, the transport of data across the multiple communication substrates ~;an take place. The unique algorithm and protocol in the nomadic routes which chooses the most appropriate device to use, is shown in FLG. 2 and FIG.
5 as part of the "nomadic roister Device Checker" through the "nonnadic roister Device Selection" across each interface.
There are numerous factors that can affect the selection of utilizing one or more devices. Such factors typically include availablebandwidth, costto initiate and maintain connection, powerrequirements and availability, and user's preference.
Another feature of the ;nomadic roister is the support for alternate or simultaneous use of various communication substrates. This is performed as part of step 5 in FIG. 6 when the source address is that of the communication substrate that the nomadic roister is going to send the packet out on. Host computers will now indirectly be able to utilize two or more communication substrates, eitherto increasethroughput or to provide soft-handoff capability.
This functionality is not supported in today's typical protocol stacks (e.g., TCPIIP or AppleTalk).
Once the nomadic routerbecomes aware of the available communication devices and activates them, the transport of data across the multiple communication substrates can take place. The unique algorithm and protocol in the nomadic roister which chooses the most appropriate device to use is part of the "nomadic roister Device Checker"
through the ''nomadic roister Device Selection" across each interface,.
There are numerous factors that can affect the selection of utilizing one or more device:;. Such factors typically includeavailabtebandwidth, cost to initiate and maintainconmection,powerrequirementsa~ldavailability, and user's preference.

WO 99146890 PCT/U~i99J05260 Hardware Sneca~cation The nomadic router carp run completely in software without any special hardware as shown in FIG.
6, or without a CPU separate from the main host, or packaged in the form of a hardware device as shown in FIG.
2. The nomadic muter can also be provided as a digital storage medium which stores the software program that implements the functionality of the router's translation processing. Examples of digital storage media include optical media {e.g. CD-ROM), magnetic media (e.g. floppy disks}, non volatile or read-only memories, or any combination thereof. The program is loaded into and run on the mobile terminal 12, or alternatively into any other computer or router which is connected to a network.
One potential implementation of the nomadic muter device is Embedded PC
Technology. As an example, the rugged PC/104 standard modules have a form-factor of 3.550" by 3.775" and typically 0.6" per module and weigh approximately 7 oz. per module. The PC/104 module's utilization of a self stacking bus with minimum component count and povver consumption (typically 1-2 \~atts per module) eliminates the need for a backplane or card cage.
The nomadic muter can nm on a 16 bit bus with an 80486 processor, for example.
The standard network access devices can support burst rates up to 10 Mbps with typical user data throughput around 1-2 Mbps.
The user bandwidth is less depending on the available wireless communication device. For example, Proxirn's 2 Mbps wireless LAN typically covers 500 yards with user data throughput around 500 Kbps. A.,s illustrated in FIG. 1, nomadic muter typically includes 3 modules; a processor 10, host device or terminal interface 10a, and communication device or system ini:erface 10b.
Another potential hardware implementation is with the CARDIO S-MOS System technology. This CPU board is basically the same size as a PCMCIA credit card adapter. It is 3.55 X 3.775 x 0.6 inches. The power requirements are +SV DC +I-10% with an operating temperature of 0 to 70°C, a storage temperature of -40 to 85°C, and relative humidity of 10% to 85% non-condensing.
The CARDIO is the most compact PCI104 compatible system available which meets the one-stack mechanical and electrical PC/104 R.ev. 2.2 specifications. Power f,~ail indicator, battery backup and automatic switchover are also possible.
The nomadic muter can. also be implemented on a small portable device such as a PC:MCIA card or partially on a PCMCIA card. In the case of a full implementation on a PCMCIA
card, the host C;PU and power supply are used to executettce Nomadic Routing and otherprotocols, algorithms, operating system, ;end application services. A hybrid implementation of part PCMCIA card and part other hardware implementation can also be used.
Annaratus Comnonents By performing packet translation in a self contained app;~ratus, processing done on thE; packets in the nomadic router does not affect and are off-loaded from the host computer. All specific translation of the packets to match the network's configuration and services available are done internally to the nomadic muter. The nomadic muter can queue, transmit, and receive data independent of vvhether or not the host computer is available WO 99146890 PCT/U~i99/OS260 or even attached. The algorithms and microcontroller built into the nomadic muter provide:. all necessary computing routines to be a fully functional network co processor independent of the host computer.
By allowing the nomadic muter to process packets independently of the host computer, the host computer can be powered down or asleep while processing is taking place, providing an increase; in battery life far the mobile host computer.
The nomadic muter can be configured with various components in several different ways. In FIG.
10, the nomadic roister contains a processor or microcontroller 11 to translate the packets stored in packets buffers in random access memory. The translation functions are stored in non-volatile memory 13 with the Real Time Operating System t'RTOS) and confiiguration informafion on what types of translation need to be. performed.
Upon startup (boot} of the nomadic roister, the RTOS and translation algorithms are loaded from non-volatile memory into RAM where they are executed from. There may be zero, one, or more host interfaces in which host computers are connected. There are one or more network interfaces.
If no host interface is available, then the nomadic roister gets the packets via the host computer from the network interface.
In FIG. 11, the nomadic muter 10 is implemented as an Application Specific Intc;grated Circuit (ASIC) or Field Programmable Gate Array (FPGA) 15. These chips embed the algorithms for packet translation.
The chip can include storage for non-volatile memory 17 which stores the configuration information such as when manually configured for the current network. The chip IS can also include random access me~.nory to buffer packets for translation in the nomadic muter before being sent off to the host or network interface.
Apparatus Packaging As described above, flee nomadic roister can be packaged i.n several different hardware configurations.
The nomadic roister can be embedded in the host computer, or network device such as a switch or routex. It can also be implemented as a PCMCIA card which plugs into the host computer or as self-contained. external box.
Each nomadic roister can have from one to many interfaces. If the roister 10 is put into the network infrastructure, it doesn't have to be corned around with the mobile user. As shown in FIG. 12a, the nomadic roister 10 is attached to a Local h~rea Network (LAN) of the network infrastructure which constitutes the communications device 14 through the system interface lOb. The L.4N 14 is connected through a conventional roister 26 to the Internet 28. In this case, the host computer interface 10a of the nomadic roister 10 is not needed since packets from the host computer I2 are received through the LAN 14.
To provide a secure interfacebetweenthe host computer 12 and network 14 to prevent host computers from being able to watch (sniff) packets on the network 14, the nom;~dic roister 10 can have one interface to the host computer 12 (terminal interface: l0a) and a second interface (lOb} to the network 14 as shown in FIG. 12b, and provide filtering to which packets and retransmitted between the various interfaces thus providing a firewall type of security device but which operates internally on the network.
In order to support multiple host computers 12a ... 12n with a single nomadic roister 10, the nomadic roister 10 may have multiple host interfaces 10a, ... l0a" as shown in. FIG.
12c and in FIG. 13 and a network or system interface lOb.

If the nomadic roister is carried around by the mobile user, it can take the form of a iPCMCIA card.
In FIG. 12d, the nomadic muter 10 is implemented as a PCMCIA card. The processing and translation capability is stored inside the card and the interface to the host computer I:! is through a PCMCIA BL1S interface or communication card 30.
As shown in FIG. 14, doe PCMCIA card can fit in a typre III slot where there is a connector on the nomadic muter 10 which accepts the communication card 30 (a type Il: PCMCIA
card.) In this mode, the nomadic roister doesn't not have to have the communication device specific components inside the PCMC'.IA card.
The nomadic roister 10 can also take the form of a type II PCMCIA card. In this form, the communication device or card 30 plugs into the opposite end of tLie nomadic roister card 10 as illustrated in FIG. I5.
TRANSLATION OPERATION OF THE NOMADIC ROUTER
Initialization and Self Configuration The nomadic roister initialization and self configuration process provides the mean. by which the nomadic muter is able to learn about the host computer and network; so it knows what translation is necessary.
Host Learning The nomadic roofer 10 us able to learn about how the host computer 12 is configuredL by looking at the content of the packets being seat from the host computer i2. :Rather than the host computer i2 sending packets directly to the muter 26 or other network device, which is what it is initially configured to d~o, the nomadic roister 10 is able redirect all outbound packets from the host computer 12 to itself. This redirection can be accomplished in several ways as described below.
1. Proxy ARP Packet Interception and Host Reconfiguration Whenever a host computer i 2 has an 1P packet which it needs to send to a roister 26 or other network device, it uses the Address Resolution Protocol (ARP) to obtain the; link layer Media Access Control address (MAC address). As illustrated in FIG. 8, when the host computer 12; broadcasts and ARP request for the MAC
address of a destination node, the nomadic roister 10 receives this AIZP
request broadcast and responds with its MAC address (not that of the destination node).
When the host computer 12 receives this ARP reply from the nomadic roister 10, which contains the MAC address of the nomadic roister 10, the host computer 12 will cache this MAC address in the host computer 12 and send all packets destined for the configured roister or network device to the nomadic roister 10. The host computer 12 will think that the MA,C address is that of the configured IP
network device, but in reality, the nomadic roister 10 is pretending (proxying) to be the device (its home gateway) that the host computer 12 expects to find.

WO 99/46890 PCT/U;S99/05260 The nomadic muter 10 is also able to reconfigure and intercept return packets from a router or other network device using the same process.
2. Promiscuous Mode .Packet Interception Since the MAC address is cached in the host computer 12 for a short period of time, the host computer 12 will not send out a new ARP request to obtain the MAC address again unless a timeout period occurs or the cache is cleared such as when the computer 12 is restarted.
When a conventional network device receives ar hears a ;packet with a MAC
address which does not match its own, it will ignore or drop the packet. Since it is possible to rapidly switch from one network environment to another using a portable computer, the nomadic router 10 must be able to intercelrtpackets even when the MAC address is not that of the nomadic router's home gateway or device.
This is accomplished by placing the nomadic router's network connection in promiscuous mode. In this mode, the network connection on the nomadic router accepts all packets being transnutted on the communication link, not just ones being broadcasted or addressed specifically to it.
3. Dynamic Host Configuration Protocol (DHCP} Service A host computer is able; to utilize the DHCP service to obtain the configuration information rather than being manually configured. The host computer utilizing the DHfCP service requires that a D:HCP server be installed on the network segment to which it is currently attached. If the host computer 12 is utilizing this service and requests configuration information using DHCP, the nomadic router 10 will intercept these requests and respond with configuration information for the host computer 12 to vuse.
Network Learning The nomadic router is able to learn about the network environment it is currently ;attached using several different methods as described below.
1. Dynamic Host ConDguration Protocol (DHCP) Whenever a different network connection is connected ~on the nomadic muter, it wall broadcast a DHCP request to obtain configuration information for the current network. If no DHCP service its available on the network, it will switch to another method to learn about the network configuration.
2. Router Information Packets Routers on the network wiii periodically broadcast router :information packets which are used to buiid routing tables and allow routers to adapt to changes in the network. The nomadic muter 10 will listen on the network for these router information packets. When one is received, it will extract out the configuration information from these packets.
3. Passive Listening WO 99/4b890 PCT/U;S99105260 By placing the nomadnc router's network connection iii promiscuous mode, where; is receives all packets not.just ones destined for it, it is able to examine alI packets on the network to discover how the network is configured. It is also able to determine the IP addresses used on the local area network and which machines are routers by the final destination address not being the next hop address.
S Using this method, the nomadic router 10 is passively able to learn how the network is configured and will elect to use an unused IP address. If that IP address does become used by another netwoik device, it will switch over to another unused IP address.
4. Manual Configuration The network configuration information can be manually configured in the nomadic i:outer 10. This information can be set using an embedded web server, Simple Network Management Protocol (S:NMP) tools, an application running on one of the computers in the network, or other suitable means. When manual co~guration is used to set the network information, the nomadic muter 10 will still learn about the host information automatically and provide all the translation capabilities so the host:
computers do not have to be aware of the correct network information of the :LAN to which they are currently connected.
1S Packet Translation The nomadic router's packet translation function provides a mapping between location and service dependent configurations used by the host computer 12 and that used by the network 14 to which it is currently attached. For outbound traffic from the host computer 12 to the netvvork 14, the translation function changes the content of the packet such as the source address, checksum, and application specificparameters, causing all packets sent out to the network 14 be directed back to the nomadic muter 10 rather than to the host computer I2.
The inbound traffic from the network 14 arriving at the; nomadic router 10, which is really for the host computer 12, is passed through the translation function so the Host computer 12 thinks that the replies were sent directly to it. The host computer I2 will be completely unaware of all the translation being; performed by the nomadic router 10.
2S The translation functions works as illustrated in FIGS. 9a and 9b. In these figures, the operations performed in the OSIIISO model application, transport, network, link and physical layers are illustrated in rows opposite the layer designations. The operations performed by the host computer 12, nomadic: router 10 and network 14 are illustrated in coluiiuns below the device designation..
'The host computer 12 will generate network packets using the current configuration stored in the host computer 12 using the standard protocol stack as shown in step 1. This configuration information is either manually configured in the host computer 12 or obtained using DH~CP.
As shown in step 2, when the host computer 12 addresses the link level destination address, the address automatically obtained using the Proxy ARP packet interception routine described earlier, this will cause the host computer 12 to send the packet to the network address of its atandard router or home gateway device, but 3S using the link level address of the nomadic router 10.

WO 99/46890 PCT/U;599/05260 In step 3, the packet is transmitted across the standard physical connection between the host computer 12 and nomadic muter 10. As shown in step 4, die nomadic routes 10 will receive the packet at the link level either due to the Proxy AIZP function which reconfigured the host connputer's MAC address, or the nomadic routes 30 will have the link level in promiscuous mode which it will cause it to receive the packet even if destined to a different MAC address.
Once the packet is passed to the network layer, shown in step 5, the nomadic muter translation function will modify the content of the packet to change the source address to that match of the nomadic router's address instead of the host computer's address. It wilt also translate other location dependent information such as the name of the local Domain Name Service (DNS) server. When translating the DNS packed, it will change the source address to that of the nomadic router's address and the destination address to that of a to cal DNS server.
Once the network layer translation is complete, the packet can be translated at the application and transport layers. The application layer is translated next, as shown in step 6, since the transport layer requires a pseudo network layer header which includes the source and destination addresses and the content from the application Layer.
At the application layer translation, any addresses which describe the source address of the host computer, such as with FTP, are translated to be that of the nomadic router's address. Any application Iayer destination addresses, such as a local proxy server, are translated to match that of the server running on the current network.
Once this application translation is complete, the transfiort layer, as shown in step ~~, can complete the checksum and any port number manipulation. The port number is manipulated if mare than one host computer 12 is attached to the nomadic muter 10. Each host computer 12 when it sends out a request using a specific port is translated to match an available inbound port on the nomadic rou.ter 10.
The port number assigned for use with each host computer 12 is stored in a table in the nomadic muter 10 and is utilized with the reply packet described later. Finally the packet is sent out over the network 14 in step 8.
When a reply packet comes in from the network 14, as ahown in step 9, the nomadic routes I O will receive the packet. In step 10, the nomadic routes 10 will perform the reverse network layer translation to set the destination address to that of the host computer rather 12 than the; nomadic router's address, ;tnd any source address to that replaced by the nomadic muter 10 in step 5.
Once this network translation is complete, the packet is translated at the application layer, as shown in step 11, to change the destination address to that of the host computer 12 and the source address to the original destination address stored from step 6. In step 12, any port manipulation performed in step 7 is changed to the original setting and a new checksum is computed. Finally, as shovm in step 13, the packet is sent to the host computer 12 which then processes the packet normally.

OPTIONS OF THE NOMADIC :ROUTER
There are numerous options and applications of the nomadic roister. These applications include, but are not limited to, Nomadic E-mail, Remote Network File Synchronization, Nomadic Database SJmchronization, Instant Network Nomadic Routing, Nomadic Intranets, and Trade Show Data Exchange. Each of these are S described in more detail below.
Nomadic E-mail Nomadic E-mail provides a synchronized yet distributed 'way for updates, reconciliation, and replicas to propagate through the Internet. At various locations in the int:ernet are nomadic router's equipped with nomadic E-mail support which provides the necessary synchronization, etc. Each nomadic rou~ter enabled for nomadic E-mail can utilize special protocols such as IMAP which provide support far mobile users without the host device having to support it (such as the case now with the POP:3 protocol standard in most Internet E-mail clients).
Remote Networlt File Synchronizer The Remote Network File Synchronization option of the nomadic roister provides copies of user files 1 S stored/cached at various locations (e.g., hotel, office, home) on other nomadic roisters equipped for remote network file synchronization. Copies of updated files are automatically synchronized and distributed among all peer locations. Local updates can be made while the host is disconnected from the nomadic routes and from the network.
Nomadic Database Synchronizer The Nomadic Database Synchronizer houses the user's (synchronized} master databases (e.g., contacts, addresses, phone numbers). The nomadic roister of the database synchronizer does not even need to be used on the network since it will interface directly with various host devices such as laptops, desktops, personal digital assistants, handheld personal computers, pagers, etc. via various standard ports.
Instant Network Nomadic Roister 2S The objective of the Instant Network nomadic roui:er is to enable rapid deployment of a communication network in any environment with little or no fixed ir~frastnzcture. The host and communication devices do not have to directly support the rapid deployment functionality.
The instant network nomadic roister distributedly and intelligently establishes a wireless (or wired) communication link between the host device and the desired communication system while perforn~ing configuration, security, multihop routing, and network level data transmission avervarious communication devices.
The nomadic roister performs all P,he necessary network creation and processing automatically to remove configuration and system support from the host system or user. Tlhe instant network nomadic roister utilizes proprietary and existing/emerging wireless communication systems, ;and multihop routing protocols.

By way of motivation, many communication infrastructures are varied and fragmented, and this problem is likely to be exacerbated as mare technologies are introduced. For example, high performance LANs, wireless services, cellulartelephon~r, satellite, ubiquitous paging networks, all provide varying degrees of coverage, cost and bandwidth/delay characteristics.
Sometimes there will be no connectivity at all because of lack of service, partial and intermittent connectivit5> as devices are plugged and unplugged from a system, damage to communication infrastructures deliberately or by accident, iossy communication as a system moves through various service areas or difficult domains, and times when multiple nestwork devices (communication substrates) can be used at the same time. The instant network nomadic router will dynamically adapt the communication internetwork, dynamicalLly creating one if necessary, to provide survivable communication in a mobile chaotic environment without: the need for centralized control or fixed infrastructures.
The rapidly deployab&e nomadic router is a device associated with each user host device (e.g., PDA
or laptop computer). It transparently provides the following capabilities for host computer systems using various wireless communication devices for physical and link layer access.
IS 1. Dynamic wireless network creation 2. Initialization into existing wireless networks 3. Automatic configuration 4. Network and subnetwork level data transmission 5. Multihop routing functionality The nomadic router can detect a device being used either by polling the interface, providing an intemrpt signal, or through specialized signaling. This in turn activates the nomadic muter to configure the device (if necessary) and establish a communication link to an appropriate corresponding interface; and wireless subnetwork. The nomadic router operates at a level between the host device generating data and the physical communication transmission device as illustrated in FIG. 1.
Nomadic Intranet The Nomadic Intranet provides all network, server type, services for users who which 1:o dynamically create an adhoc network. This is similar to the instant network nomadic muter except the nomadic intranet is a single device with multiple ports into which iaptop/devices can be plugged.
The instant network nomadic router is distributed to (one per} each host device. The nomadic intranet not only provides adhoc networking but can also provide services such as temporary file storage, protocol conversion, act as a print server, and provide other services described as part of the Basic nomadic muter.
Trade Show Nomadic Rauter The Trade Show nomadic router not only provides the basic nomadic muter functionality for an exhibitor's computer that is brought to the show, but also provides lead capture and/or inforTrratian distribution.

WO 99/46890 PCT/U;S99I05260 Lead capture can be provided for by interfacing with a badge reader to read the attendee's information. This information is then captured by the nomadic router and made availaible in the exhibitor's lead d;~tabase.
The nomadic router can also provide a mechanism for distributing information to the attendee's personalized web page or sent via e-mail directly across the Internet. The exhibitor's computer is able to control the information flow with the nomadic router by running software, such as a web browser, which talks with the service/control software stored in the nomadic router. The standard web browser can control display and capture of lead information, collection of qualification information, and selection of information to be distributed back to the attendee.
Fixed Nomadic Router The Fixed nomadic muter provides the same basic fwnctionality and architecture ;as the portable nomadic router but is stored in one ilocation. The fixed nomadic rouier acts as a surrogate or "Home Agent" for the user when he/she is away on travel. When the user wishes to register or utilize their host device elsewhere in the network, the portable nomadilc router will register with the fixed nomadic muter where it is temporarily attached to the network so information can be forwarded to the user's new location. The fixed nomadic router can also be used to house the master copy of the user's E-mail for the nomadic E-mail service, or files for the nomadic file synchronizer.
Mobile Virtual Private Network The nomadic router provides the mapping between the location based 1P address used in the intemet today and the permanent user based address housed in the host CPU. This mapping is done without support or knowledge of such mapping by the host CPU or user. The Internet RFC 2002 Mobile IP protocol specifies the mapping between permanent and temporary IP addresses. The unique aspect of th.e nomadic router is that the Mobile IP protocols are not necessarily running in, or supported by, the host CPU but rather are internal to the nomadic router.
By implementing this protocol as part of the translation :function in the nomadic routtr, the nomadic router can encapsulatepackets from the host computer and transmit tlhem back to the fixed nomadic muter which are sent out (un-encapsulated} on the native (home) network. Replies from the home network are :received by the fixed nomadic router and are encapsulated and sent back to the nomadic router.
When packets are transmitted between the nomadic router and fixed nomadic muter, the packets are encrypted and sent using the Internet Tunneling Protocol.
Since the nomadic roofer provides location independence and the fixed nomadic rout:cr forwards all packets from a corresponding host to the host computervia the nomadic muter, any changes in the location, failure of a network link, or attachment point of the mobile host computer does not cause any open session to be lost.
Tlus session loss prevention is possible since the fixed nomadic router pretends to be the mobile host computer, and the nomadic router pretends to b ~ the home network. The fixed nomadic router and nomadic router translation functions hide the link and network Ioss from the transport and application session.

WO 99/46890 PCT/tJ~~99/05260 Various modifications will become possible for those skilled in the art after receiving the teachings of the present disclosure without departing from the scope thereof.
INDUSTRIAL APPLICABiI.ITY
The present invention is broadly applicable to the field of electronic data communications using computers and other devices.

Claims (54)

WHAT IS CLAIMED IS:

1. A translator for connecting a terminal to a communication system, the terminal being configured to be connected to a home device, the translator comprising:
an interface for connection to the terminal and to the system: and a processor connected to the interface, the processor being configured to appear as the home device to the terminal, and to appear as the terminal to the system.

2. A translator as in claim 1, in which:
the terminal has a permanent address;
the translator has a translator address;
the terminal transmits outgoing data to the system including the permanent.
address as a source address; and the processor translates the outgoing data by replacing the permanent address with the translator address as the source address.

3. A translator as in claim 2, in which the permanent address is an Internet Protocol (IP) address.

4. A translator as in claim 2, in which the translator address is an Internet Protocol (IP) address.

5. A translator as in claim 2, in which the processor determines the permanent address from data transmitted by the terminal.

6. A translator as in claim 5, in which:
the terminal transmits an Address Resolution Protocol (ARP) packet which.
includes the permanent address to the translator: and the processor determines the permanent address from the ARP packet.

7. A translator as in claim 5, in which:
the processor is configured to operate in a promiscuous mode in which it translates all outgoing data; and the processor determines the permanent address from outgoing data.

8. A translator as in claim 1, in which:
the translator has a translator hardware address; and the processor is configured to adapt the terminal to transmit outgoing data to the translator hardware address.

-20-y. A translator as in claim 1, in which:
the terminal has a permanent address;
the translator has a translator address;
the translator receives incoming data from the system including the translator address as a destination address; and the processor translates the incoming data by replacing the translator address with the permanent address as the destination address.

10. A translator as in claim 1, in which:
the terminal has a permanent address;
the translator has a translator address:
the terminal transmits outgoing data to the system including the permanent address as a source address;
the processor translates the outgoing data by replacing the permanent address with the translator address as the source address;
the translator receives incoming data from the system including the translator address as a destination address; and the processor translates the incoming data by replacing the translator address with the permanent address as the destination address.

11. A translator as in claim 1, in which the processor is configured to automatically configure itself to the system.

12. A translator as an claim 11, in which the processor configures itself to the system using Dynamic Host Configuration Protocol (DHCP).

13. A translator as in claim 11, in which the processor configures itself to the system by operating in a promiscuous mode in which it accepts all incoming data and extracts system information therefrom.

14. A translator as in claim 11, in which the system comprises at least one translator which broadcasts information packets that include system information; and the processor configures itself to the system by receiving and extracting the system information from the information packets.

15. A translator as in claim 11, in which the processor is configured to have system information entered therein manually.

16. A translator as in claim 1, in which the translator its configured to communicate with another translator that is connected to the home device and is configured to function as a home agent.

17. A translator as in claim 1, comprising a hardware device incorporating the interface and processor, the hardware device being connected to the terminal and to the system.

18. A translator as in claim 17, in which the hardware device is attached to the terminal.

19. A translator as in claim 17, in which:
the system comprises a component; and the hardware device is attached to the component.

20. A translator as in claim 17, in which:
the system comprises a network; and the hardware device is connected to a point on the network.

21. A translator as in claim 17, in which:
the system comprises a network; and the hardware device is connected between the terminal and the network.

22. A translator as in claim 17, in which the hardware device comprises a card including a memory in which software implementing the processor is stored, and a computing device for running the software.

23. A translator as in claim 22, in which the card is configured to be plugged into the terminal.

24. A translator as in claim 17, in which the hardware device comprises an integrated circuit including a memory in which software implementing the processor is stored, and a computing device for running the software.

25. A translator as in claim 24, in which the integrated circuit is configured to be plugged into the terminal.

26. A translator as in claim 1, comprising software which is stored and running in the terminal.

27. A translator as in claim 1, comprising software which is stored and running in a component of the system.

28. A translator as in claim 27, in which the system comprises a network in which the component is connected.

29. A translator as in claim 1, in which the interface comprises a terminal interface for connection to the terminal, and a system interface for connection to tie system.

30. A translator as in claim 29, in which the processor is connected between the terminal interface and the system interface.

31. A translator as in claim 29, in which:
the system interface is connected to the system;
the terminal interface is unused; and the terminal is connected to the system.

32. A translator as in claim 1, in which the processor is configured to translate Transport Control Protocol/Internet Protocol (TCP/IP) packets.

33. A translator as in claim 1, in which the processor is configured to have a filtering capability.

34. A translator as in claim 1, in which the processor is configured to utilize alternate communication devices in the system transparently to the terminal.

35. A translator as in claim 1, in which the translator is configured to provide session loss prevention to the terminal in the event of a failure.

36. A translator as in claim 1, in which the processor is configured to perform dynamic creation and maintenance of a wireless network with capability to route a data packet across multiple wireless hops transparently to the terminal.

37. A translator as in claim 1, in which:
the system comprises first and second networks;
the terminal and translator are connected to the first network; and the processor is configured to appear as the second network to the terminal, and to appear as the terminal to the second network.

38. A translator as in claim 1, in which the processor is configured to perform data protocol conversion.

39. A translator as in claim 1, in which the processor is configured to respond to a data request on a remote resource which was cached locally in the translator.

40. A translator as in claim 1, in which the processor is configured to provide file synchronization across the system.

41. A translator as in claim 1, in which the processor is further configured to perform database synchronization among a plurality of terminals.

42. A translator as in claim 1, in which the processor is configured to provide e-mail with file replication and reconciliation without the terminal having to request replication or reconciliation.

43. A translator as in claim 1, in which:
the terminal transmits outgoing data to the system including a first address as a destination address;
the translator stores a second address which corresponds to the first address;
and the translator translates the outgoing data by replacing the fast address with the second address as the destination address.

44. A translator as in claim 43, in which:
the translator receives incoming data from the system including the second address as a source address; and the translator translates the incoming data by replacing the second address with the first address as the source address.

45. A digital storage medium for storing a computer program which implements the functionality of a translator for performing data translation between a terminal that: is configured to be connected to a home device, to a system, the program being configured such that the translator appears as the home device to the terminal, and appears as the terminal to the system.

46. A medium as in claim 45, in which:
the terminal has a permanent address;
the translator has a translator address;
the terminal transmits outgoing data to the system including the permanent address as a source address; and the translator is configured to translate the outgoing data by replacing the permanent address with the translator address as the source address.

47. A medium as in claim 46, in which the permanent address is an Internet Protocol (IP) address.

48. A medium as in claim 46, in which the translator address is an Internet Protocol (IP) address.

49. A medium as in claim 46, in which the program is configured to determine the permanent address from data transmitted by the terminal.

50. A medium as in claim 49, in which:
the terminal transmits an Address Resolution Protocol (ARP) packet which includes the permanent address to the translator; and the translator is configured to determine the permanent address from the ARP
packet.

51. A medium as in claim 49, in which:
the translator is configured to operate in a promiscuous mode in which it translates all outgoing data; and the translator is further configured to determine the permanent address from outgoing data.

52. A medium as in claim 45, in which:
the translator has a translator hardware address; and the translator is configured to adapt the terminal to transmit outgoing data to the translator hardware address.

53. A translator as in claim 45, in which:
the terminal has a permanent address;
the translator has a translator address;
the translator receives incoming data from the system including the translator address as a destination address; and the translator is configured to translate the incoming data by replacing the translator address with the permanent address as the destination address.

54. A translator as in claim 45, in which:
the terminal has a permanent address;
the translator has a translator address;
the terminal transmits outgoing data to the system including the permanent address as a source address;

the translator is configured to translate the outgoing data by replacing the permanent address with the translator address as the source address;
the translator receives incoming data from the system including the translator address as a destination address; and the transistor is configured to translate the incoming data by replacing the translator address with the permanent address as the destination address.