Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1999-08-10
2003-09-09
Jung, Min (Department: 2663)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S469000, C370S487000, C725S111000
Reexamination Certificate
active
06618386
ABSTRACT:
BACKGROUND OF THE INVENTION
1. The Field of the Invention
The present invention relates to electrical computers and data processing systems. Specifically, the present invention relates to a virtual bridge for enabling a cable modem to be self-hosted by a computer, a set-top box, or the like.
2. The Prior State of the Art
The Internet is a worldwide interconnection of networks over which computers can exchange information. Never before have human beings had access to so much information from the comfort of their own homes or offices. For Wide Area Networks (WANs) such as the Internet, a computer typically employs a modem to send information to and receive information from other connected computers. There are many types of modems each corresponding to a specific type of medium used to deliver this information.
One common modem uses Plain Old Telephone Service (POTS) to send and receive information. POTS modems have an advantage in that they use a transmission medium that is available by just connecting the modem with the nearest phone jack. Thus, the POTS modem does not require expensive capital investment to set up a connection to the Internet. Although POTS modems are easy and inexpensive to connect to the Internet, the transmission speeds available over plain old telephone service are relatively slow. Currently, POTS modems are capable of information exchange at up to only 56,000 bits per second (bps) or approximately 0.056 megabits per second (Mbps). While faster POTS modems may eventually become available, it is not currently anticipated that POTS modems can become significantly faster due to physical limitations in the telephone lines themselves.
Telephone companies are now offering services that bypass the relatively slow telephone lines to establish a more direct connection to the Internet. For example, T
1
, connections permit information exchange in the megabits per second (Mbps) range. T
2
and T
3
connections allow for even higher speed information exchange. Currently, T
1
, T
2
and T
3
connections respectively permit information exchange at approximately 1.544 Mbps, 6.312 Mbps and 44.736 Mbps. Although these direct T
1
, T
2
and T
3
connections permit information exchange orders of magnitude faster than is available over plain old telephone service, they are typically much more expensive to obtain and/or maintain than plain old telephone service since each connection requires dedicated circuitry. Furthermore, telephone companies typically provide both the plain old telephone service and the T
1
, T
2
and T
3
connections. To facilitate free market competition, it would be desirable for a consumer to have alternative suppliers of Internet access.
A cable modem is a device that hooks up to the Internet through a cable system provided by a cable operator. Assuming that the cable operator facilitates Internet access as many cable operators do, Internet access is obtained by plugging the cable modem into a cable connection that typically already exist (or may be readily installed) in many homes and business. Thus, the cost of connecting a cable modem to the Internet is relatively small compared to establishing T
1
, T
2
and T
3
connections since the extensive cable network that supports communication already exists. Thus, there is no need to establish extensive dedicated circuitry to support each new end user.
Furthermore, dialing into the Internet is not needed since data may be communicated to or from the end-user over the cable system without dialing into the cable system. Thus, the initial connection to the Internet is much faster compared to using plain old telephone service.
In addition, cable modems allow for much faster information exchange than is available over plain old telephone service. An individual cable modem end user may experience information exchange speeds of from 0.5 Mbps to 1.0 Mbps or more depending on the cable network architecture and traffic load. This represents a speed that is at least an order of magnitude faster than is currently available over plain old telephone service. Furthermore, cable information exchange speeds may be further increased due to future improvements in cable technology. Thus, cable modems provide a low cost, high-speed alternative for Internet access.
In a typical cable modem configuration, the cable modem is external to and separately addressable from the end user's computer system. The end user's computer is then connected to the cable modem using, for example, a network card. One reason for which the cable modem is external to the end-user's computer is that the cable modem may have access control settings that are to be set by the cable operator, not by the end-user. For example, the cable operator may want to prohibit access to certain services unless the end-user has communicated a subscription to the cable indicating a willingness to abide by certain terms. Allowing the end-user to directly access and set these access control settings would bypass the very purpose for having the access control settings. Thus, having the cable modem be external to the end-user's computer has the advantage of the cable supplier retaining control of the access control settings within the cable modem.
From the standpoint of the computer, the cable modem is a bridge that allows the computer to communicate with other network components and to receive network resources. The cable modem acts as a bridge by transferring IEEE 802.3 Ethernet data packets, for example, to the computer.
As the cable modem is external, the cable modem does not use the processing capability of the central processing unit (CPU) of the end user's computer system. Also, the cable modem does not share memory with the end user's computer. Thus, the cable modem has its own CPU and memory which increases the cost of the cable modem.
Furthermore, the introduction of an external cable modem adds a degree of complexity to the set up of the computer system. For example, the computer user must do more than just directly connect the computer system to the cable network to have Internet access. The user must connect the cable modem to the cable network, then connect the computer system to the cable modem.
Thus, what is desired is a computer system that provides Internet access through a cable modem. Furthermore, it is desired is that the cable modem not require its own dedicated CPU and/or memory. Also, it is desired that the cable modem be easier to set up than conventional external cable modems. In addition, it is desired that the access control settings of the cable modem not be directly accessible and changeable by the end-user.
SUMMARY OF THE INVENTION
In accordance with the present invention, a computer system hosts a cable modem which can be connected to an extensive cable network managed by a cable operator. While cable operators have traditionally offered only television programming over these cable networks, cable operators have recently begun offering Internet service as well. The cable modem of the present invention may communicate over the Internet using these cable networks with the cooperation of the cable operators.
Typically, cable modems for use with the Internet are “external” in that the cable modem exists as a separate device from the computer system. The external cable modem connects directly to the cable network and bridges the cable network to the computer system using a medium such as an Ethernet or a universal serial bus.
In the present invention, the cable modem not external, but is integrated within and hosted by the computer system. Specifically, the cable modem uses the same CPU and memory that are used by the operating system of the computer system. Since a separate CPU and memory are not required for the cable modem, the cost of the combined cable modem and computer system is reduced.
Even though the cable modem is hosted by the computer system, the cable modem has a different network address than the other components in the computer system. When the cable modem receives a data packet having the network ad
Liu Jun
Parchem John M.
Shoff Daniel J.
Tjong Soemin
Jung Min
WEBTV Networks, Inc.
Workman & Nydegger & Seeley
LandOfFree
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