Multiplex communications – Communication techniques for information carried in plural... – Adaptive
Reexamination Certificate
1997-02-06
2001-06-05
Zimmerman, Brian (Department: 2735)
Multiplex communications
Communication techniques for information carried in plural...
Adaptive
C370S474000
Reexamination Certificate
active
06243394
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to transmission of data using an asymmetric digital subscriber line (ADSL) channel and, more particularly, to apparatus for accessing an ADSL channel.
BACKGROUND OF THE INVENTION
The rapid growth of the “information highway” has created the need for high-speed, low-cost techniques for transmitting data to and from homes, small businesses, schools and the like. At the data rates of conventional modems, the transmission of detailed graphics, for example, typically requires a time that may be annoying to the user. A web page containing detailed graphics of 100 kilobytes may require 27 seconds for transmission. Optical fiber networks and CATV networks have sufficient bandwidth to permit high speed data transmission. However, the infrastructure is not presently available to provide data services to consumers on optical fiber or CATV networks on a widespread basis and at low cost.
An ADSL standard for data transmission is being developed to address these issues. Data transmission, according to the ADSL standard, permits transmission of simplex and duplex digital data signals over the conventional twisted wire pairs that are used for plain old telephone service (POTS). The digital data signals are transmitted at frequencies above the baseband analog POTS band (0-4 kilohertz). The ADSL standard is a physical layer standard providing for a simplex downstream channel at a maximum rate of 6.2 megabits per second and a minimum rate of 1.544 megabits per second. The ADSL standard also includes a duplex digital channel at optional rates of 64 kilobits per second, 160 kilobits per second, 384 kilobits per second and 576 kilobits per second. The ADSL standard takes advantage of the fact that most consumer applications, such as Internet access, access to online information services, access to private networks and work-at-home applications, require a larger bandwidth into the home than out of the home. ADSL transport technology is described by R. Olshansky in “Moving Toward Low-Cost Access to the Information Highway”, Telephony, Nov. 7, 1994, pp. 31-37.
The basic ADSL architecture includes an ADSL interface unit at the telephone company central office (CO) and an ADSL interface unit at the customer location, interconnected by a twisted pair of conductors. Each ADSL interface unit includes a POTS splitter and ADSL modem. The ADSL modem transmits and receives digital data on the twisted pair at the selected ADSL transmission rates. At the central office, the ADSL interface unit receives and transmits digital data from a wide area network. The POTS splitter frequency multiplexes the high speed digital data and the analog POTS signal onto the twisted pair for transmission. The POTS splitter at the customer location decouples the analog POTS signal onto the existing POTS wiring in the home. The ADSL modem receives the ADSL data signals and forwards them to the customers PC or LAN. The interface between the LAN and the ADSL channel must be configured to insure efficient transfer of digital data. Similarly, the interface between the wide area network and the ADSL channel at the CO must be configured to insure efficient transfer of digital data.
SUMMARY OF THE INVENTION
According to a first aspect of the invention, apparatus is provided for controlling data communication between a local area network (LAN) and a remote device through an ADSL channel. The apparatus comprises an ADSL modem coupled to the ADSL channel, a protocol converter coupled to the ADSL modem and a switching port controller coupled between the protocol converter and a port of the LAN. The protocol converter converts the protocol of data packets transmitted from the LAN through the ADSL channel from a LAN protocol to an ADSL protocol and converts the protocol of data packets transmitted through the ADSL channel to the LAN from ADSL protocol to LAN protocol. The switching port controller includes first means for determining if a destination address of a data packet received through the LAN port matches one of the source addresses in the LAN and for forwarding the data packet to the protocol converter when the destination address of the data packet does not match one of the source addresses in the LAN. The switching port controller further includes second means for forwarding data packets received from the protocol converter to the LAN port.
The first means of the switching port controller preferably includes an address table, means for storing in the address table source addresses of data packets received through the LAN port and means for comparing the destination address of the data packet received through the LAN port with the source addresses stored in the address table to determine if the destination address matches one of the source addresses in the LAN.
According to another aspect of the invention, apparatus is provided for controlling data communication between a LAN having a plurality of segments and a remote device through an ADSL channel. The apparatus comprises an ADSL modem coupled to the ADSL channel, a protocol converter coupled to the ADSL modem and a plurality of switching port controllers respectively coupled between the protocol converter and the plurality of LAN segments. Each of the switching port controllers includes a LAN port coupled to one of the LAN segments and first means for determining if a destination address of a data packet received through its LAN port matches one of the source addresses in the LAN and for forwarding the data packet to the protocol converter when the destination address of the data packet does not match one of the source addresses in the LAN. Each of the switching port controllers further includes second means for forwarding data packets received from the protocol converter to its LAN port.
Each switching port controller preferably includes an address table, means for storing in the address table source addresses of devices connected to the LAN port of the switching port controller and means for comparing the destination address of the data packet with the source addresses in the address table to determine routing of the data packet.
When the apparatus includes a plurality of switching port controllers, each switching port controller preferably includes means for forwarding the destination address of the data packet to other ones of the switching port controllers for comparison with the source addresses in the address tables of the other switching port controllers and means for forwarding the data packet to another switching port controller when the destination address matches one of the source addresses in the address table of the other switching port controller.
The second means of each of the switching port controllers preferably includes means for comparing the destination address of data packets received from the protocol converter with the source addresses stored in the address table and means for forwarding the data packet to its LAN port when the destination address of the data packet matches one of the source addresses in the address table.
According to a further aspect of the invention, apparatus is provided for controlling data communication between a wide area network (WAN) and remote devices through a plurality of ADSL channels. The apparatus comprises a WAN protocol converter coupled to the wide area network and a plurality of ADSL channel controllers respectively coupled between the WAN protocol converter and the plurality of ADSL channels. The WAN protocol converter converts the protocol of data packets transmitted to the wide area network from a first protocol to a WAN protocol and converts the protocol of data packets transmitted from the wide area network to one of the ADSL channels from the WAN protocol to the first protocol. Each ADSL channel controller comprises an ADSL modem coupled to one of the ADSL channels and a switching port controller coupled between the WAN protocol converter and the ADSL modem. Each of the switching port controllers comprises first means for determining if a destination address of a data pac
Suchyta Leonard Charles
Verizon Laboratories Inc.
Weixel James K.
Zimmerman Brian
LandOfFree
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