Abstract:
A network architecture that supports a dynamic protocol on a local exchange bridged network is implemented by utilizing a bridge to provide an interface between a piece of customer premise equipment (CPE) and a modem. By utilizing a bridged modem, the CPE used by each customer can be mapped to a different virtual local area network (VLAN).

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to network architectures and, more particularly, to a network architecture that supports a dynamic IP addressing protocol across a local exchange bridged network.  
         [0003]     2. Description of the Related Art  
         [0004]     A mixed service telecommunications architecture is an architecture for delivering video, data, and voice services over a conventional twisted-pair telephone wire to customer premise equipment (CPE) at a customer location. The services and supporting CPEs are often provided by different service providers, with a set-top box for video from a first supplier, internet service from a second supplier, and plain old telephone service (POTS) from a third supplier.  
         [0005]      FIG. 1  shows a block diagram that illustrates a portion of a prior-art mixed service telecommunications architecture  100 . Architecture  100  includes an asynchronous transfer mode (ATM) network  110  that has a number of interconnected ATM switches AT 1 -ATg, and a number of edge devices ED 1 -EDm that are connected to the switches AT 1 -ATg.  
         [0006]     Each edge device ED converts data from an input data format to an ATM format. In the ATM format, data is loaded into fixed length packets known as cells. Each cell has a header section and a data section. The header section, in turn, includes a virtual connection identifier (VCI) that identifies the destination of the cell.  
         [0007]     Architecture  100  further includes a local exchange bridged network  112  that is connected to edge device ED 1 , an internet server  114  that is connected to edge device ED 2 , and a video server  116  that is connected to edge device ED 3 . Bridged network  112 , in turn, includes a number of bridges BR 1 -BRn that are connected to edge device ED 1 , and a number of xDSL modems DS that are connected to each bridge BR. In addition, each bridge BR has a number of ports PT 1 -PTj, with each modem DS being connected to one of the ports PT. Further, a number of CPEs, such as set top boxes ST and personal computers PC, are connected to each modem DS.  
         [0008]     In operation, when a CPE, such as a set top box or personal computer, boots up, the CPE outputs a data packet to its associated modem which, in turn, outputs the data packet to its associated bridge. The data packet includes the address of a video server (the packet destination), and the internet protocol (IP) address (which includes the MAC address) of the CPE.  
         [0009]     The associated bridge receives the data packet on one of its ports, determines the destination of the data packet, and forwards the data packet to the destination address. When the destination address is not connected to the associated bridge, the bridge forwards the data packet to other locally connected bridges and the ATM network via an edge device. The ATM network then forwards the cells to the destination address.  
         [0010]     For example, when set top box ST 1  boots up, set top box ST 1  outputs a data packet to modem DS 1  which, in turn, outputs the data packet to bridge BR 1 . Bridge BR 1  receives the data packet from modem DS 1  on port P 1 . Bridge BR 1  does not know if the data packet came from set top box ST 1  or personal computer PC 1 , only that the packet came from port P 1 .  
         [0011]     Bridge BR 1  determines the destination of the data packet, and forwards the data packet to the destination address. When the destination address is not connected to bridge BR 1 , bridge BR 1  forwards the data packet to edge device ED 1  and bridges BR 2 -BRg. Edge device ED 1  receives the data packet, converts the data packets into ATM data cells, and forwards the cells to switch AT 1 .  
         [0012]     Switch AT 1  examines the VCI in the header, and routes the cell to one of a number of ATM switches based on the VCI. Each succeeding ATM switch that receives the cell repeats the process until the cell reaches its destination. The examination and routing is performed in hardware without software support. As a result, ATM network  110  is able to provide high-speed data communication.  
         [0013]     In the present example, switch AT 1  forwards the cells to switch AT 3 . Edge device ED 3  converts the data cells received by switch AT 3  into a local data format, and passes the data onto video server  116 . Video server  116  outputs a response back to set top box ST 1  that includes, in addition to other information, boot up information for box ST 1 . (A similar process occurs with internet server  114  when a personal computer boots up for network access.)  
         [0014]     One severe limitation of architecture  100  is that each CPE (each set top box ST and each personal computer PC) in architecture  100  has a static IP address. In addition, each CPE has a fixed address from which to obtain start up (boot strap) information. This requires complex customer installations, network configurations, and coordination between the different service providers.  
         [0015]     A much simpler and lower cost approach is to utilize a dynamic addressing scheme to assign IP addresses on a temporary basis as the IP addresses are needed. With a dynamic protocol, such as the dynamic host configuration protocol (DHCP), a CPE, such as a set top box, is a member of a virtual local area network (VLAN).  
         [0016]     In the protocol, the CPE requests an IP address from an unknown source in the VLAN (only one device in the VLAN responds to the IP address request), thereby eliminating the need to have a fixed address for boot strap information. In addition, the device is assigned a new IP address each time the set top box boots up, thereby eliminating the need to have static IP addresses.  
         [0017]     Thus, with a dynamic protocol, a technician does not need to manually set a static IP address for a device, or manually set the destination address of the boot strap server, because the device is assigned a new IP address from an unknown server each time the device goes onto the network. This makes rolling out new equipment significantly easier for the service providers.  
         [0018]     Current generation, local exchange bridged networks, however, are incompatible with dynamic protocols.  FIG. 2  shows a schematic diagram that illustrates a hypothetical, dynamic protocol, bridged network architecture  200 . Network architecture  200  is similar to network architecture  100  and, as a result, utilizes the same reference numerals to designate the structures that are common to both architectures. As shown in  FIG. 2 , architecture  200  differs from architecture  100  in that architecture  200  includes a DHCP internet server  214  in lieu of internet server  114 , and a DHCP video server  216  in lieu of video server  116 .  
         [0019]     In operation, when set top box ST 1  boots up, set top box ST 1  outputs a data packet to modem DS 1  which, in turn, outputs the data packet to bridge BR 1 . The data packet includes a destination address, and the MAC address of the sending device which, in the present example, is set top box ST 1 . When initiating a boot strap protocol, the destination address is a dynamic host configuration protocol (DHCP) request.  
         [0020]     Bridge BR 1  receives the data packet on port P 1 . As in the previous example, bridge BR 1  does not know if the data packet came from set top box ST 1  or personal computer PC 1 , only that the packet came from port P 1 . Bridge BR 1  determines whether the data packet is a broadcast packet, which is to be broadcast to each other member of the VLAN, or a routed packet which is to be routed to a specific address.  
         [0021]     When the destination address is a DHCP request, bridge BR 1  regards the data packet as a broadcast packet. In this case, bridge BR 1  turns to a look-up table to identify the other members of the VLAN of port P 1 , and output the data packet to each member of the VLAN. In this case, because set top box ST 1  requires a DHCP video server and personal computer PC 1  requires a DHCP internet server, the video server and the internet server are both included in the same VLAN. As a result, the data packet containing the request is sent to both the video server and the internet server.  
         [0022]     For devices that are not connected to bridge BR 1 , bridge BR 1  outputs the data packet to edge device ED 1  and bridges BR 2 -BRg. Edge device ED 1  receives the data packets addressed to the different devices, converts the data packets into ATM data cells, and forwards the cells to switch AT 1 . Switch AT 1  then forwards the cells to switches AT 2  and AT 3 .  
         [0023]     All works well if switch AT 3  is the first to receive the cells that include the DHCP request. In this case, edge device ED 3  converts the data cells received by switch AT 3  into a local data format, and passes the data onto DHCP video server  116 . DHCP video server  116  links an IP address to the MAC address of set top box ST 1 , and outputs a response back to set top box ST 1  identifying the IP address (along with other information boot up information).  
         [0024]     On the other hand, if switch AT 2  is the first to receive the cells that include the DHCP request, edge device ED 2  converts the data cells received by switch AT 2  into a local data format, and passes the data onto DHCP internet server  114 . DHCP internet server  114  links an IP address to the MAC address of set top box ST 1 , and outputs a response back to set top box ST 1  identifying the IP address. In this case, set top box ST 1  begins to communicate with internet servers rather than video servers, and the system fails.  
         [0025]     One solution to this problem has been to utilize a dynamic protocol with video, and install special recognition software (e.g., PPPoE and PPPTP) on the personal computers that allows IP address negotiation. This approach, however, requires each personal computer to run additional client software, and creates additional support costs for service providers.  
         [0026]     Another limitation of architecture  100  is that each CPE (each set top box ST and each personal computer PC) in architecture  100  contends for Ethernet bandwidth. One solution to this problem has been to prioritize IP addresses. Although workable, this approach adds another layer of complexity.  
         [0027]     Thus, there is a need for a network architecture that supports a dynamic protocol on a local exchange bridged network, and reduces contention for Ethernet bandwidth.  
       SUMMARY OF THE INVENTION  
       [0028]     The present invention provides a network architecture that supports a dynamic protocol on a local exchange bridged network by utilizing a bridge to provide an interface between a piece of customer premise equipment (CPE) and a modem. By utilizing a bridge, each piece of CPE can be mapped to a different virtual local area network (VLAN). This allows a dynamic protocol to be used on local exchange bridged network systems, thereby significantly simplifying the process for rolling out and maintaining new CPE-based services. In addition, the present invention reduces contention for Ethernet bandwidth.  
         [0029]     A network architecture in the present invention comprises a bridged modem that includes a bridge circuit. The bridge circuit has a receiving circuit that has a plurality of customer premise equipment (CPE) ports. Each CPE port, in turn, is associated with a VLAN. The receiving circuit forms a received data packet when a data packet is received from a CPE port.  
         [0030]     The bridge circuit also has an address identifier circuit that is connected to the receiving circuit. The address identifier circuit determines whether the received data packet includes an IP address request. In addition, the bridge circuit has a look up circuit that identifies a member of a VLAN when the received data packet includes an IP address request.  
         [0031]     The bridge circuit further includes an output circuit that is connected to the address identifier circuit and the look up circuit. The output circuit generates an addressed data packet that is addressed to the member of the VLAN, and forwards the addressed data packet from a bridge output after the addressed data packet has been generated.  
         [0032]     The modem also includes a modem circuit that has a receiving circuit which is connected to the bridge output. The receiving circuit receives the addressed data packet from the output circuit. The modem circuit also includes a modulation circuit that is connected to the receiving circuit. The modulation circuit modulates the data in the packet to form a data signal. In addition, the modem circuit includes a transmitting circuit that is connected to the modulation circuit. The transmitting circuit transmits the data signal from a transmit port.  
         [0033]     A better understanding of the features and advantages of the present invention will be obtained by reference to the following detailed description and accompanying drawings that set forth an illustrative embodiment in which the principles of the invention are utilized. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0034]      FIG. 1  is a block diagram illustrating a portion of a prior-art mixed service telecommunications architecture  100 .  
         [0035]      FIG. 2  is a schematic diagram illustrating a hypothetical, dynamic protocol, bridged network architecture  200 .  
         [0036]      FIG. 3  is a block diagram illustrating a network architecture  300  in accordance with the present invention.  
         [0037]      FIG. 4  is a block diagram illustrating a bridged modem  400  in accordance with the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0038]      FIG. 3  shows a block diagram that illustrates a network architecture  300  in accordance with the present invention. Architecture  300  is similar to architecture  100  and, as a result, utilizes the same reference indicators to indicate the structure that is common to both architectures.  
         [0039]     As shown in  FIG. 3 , architecture  300  differs from architecture  100  in that architecture  300  includes a DHCP internet server  314  in lieu of internet server  114 , and a DHCP video server  316  in lieu of video server  116 . In addition, architecture  300  utilizes a number of bridged modems DL in lieu of xDSL modems DS. Bridged modems DL differ from standard xDSL modems DS in that a bridged modem DL includes an Ethernet bridge that maps a MAC address to a specific ATM address, and an xDSL modem circuit.  
         [0040]      FIG. 4  shows a block diagram that illustrates a bridged modem  400  in accordance with the present invention. As shown in  FIG. 4 , bridged modem  400  has a bridge circuit  410  and an xDSL modem circuit  412 . Bridge circuit  410 , in turn, includes a receiving circuit  414  that has a series of customer premise equipment (CPE) ports PS 1 -PSx. Each CPE port PS is associated with a virtual local area network. In operation, receiving circuit  414  forms a received data packet when a data packet is received from a CPE port PS.  
         [0041]     As further shown in  FIG. 4 , bridge circuit  410  includes an address identifier circuit  416  that is connected to receiving circuit  414 . In operation, address identifier circuit  416  examines the received data packet to determine whether a DHCP IP address request is present. Bridge circuit  410  further includes a look up circuit  420  that identifies the members of the VLAN when an IP address request is present in the received data packet.  
         [0042]     In addition, bridge circuit  410  includes an output circuit  422  that is connected to address identifier circuit  416  and look up circuit  420  that generates an addressed data packet for each member of the VLAN. Further, output circuit  422  forwards the addressed data packet from a bridge output after the addressed data packet has been generated.  
         [0043]     As noted above, in addition to bridge circuit  410 , bridged modem  400  also includes xDSL modem circuit  412 . Modem circuit  412  includes a receiving circuit  430  that is connected to the bridge output to receive the addressed data packet from output circuit  422 . In addition, modem circuit  412  includes a modulation circuit  432  that is connected to receiving circuit  430  that modulates the data in the packet to form a data signal. Further, modem circuit  412  includes a transmitting circuit  434  that is connected to modulation circuit  432 . Transmitting circuit  434  transmits the data signal from a transmit port.  
         [0044]     In operation, when a device, such as a set top box or a computer, boots up, the device outputs a data packet that includes a DHCP IP address request, and the MAC address of the device. The port PT connected to the device receives the data packet, while receiving circuit  414  forms the received data packet.  
         [0045]     Following this, address identifier circuit  416  determines whether the received data packet includes a DHCP IP address request. When no DHCP IP address request is present, output circuit  420  determines whether the received data packet is a broadcast packet, which is to be broadcast to each other member of the VLAN, or a routed packet which to be routed to a specific address.  
         [0046]     When a DHCP address request is present, output circuit  422  regards the received data packet as a broadcast packet. In this case, output circuit  422  turns to a look-up table in look up circuit  420  to identify the other members of the VLAN that is associated with the receiving port PT. After this, output circuit  422  generates an addressed data packet for each member of the VLAN.  
         [0047]     In the invention, only one type of DHCP server is a member of the VLAN. As a result, the addressed data packet that includes the DHCP request can only go to the correct DHCP server. For example, when the device is a set top box, the port PT connected to the set top box is associated with a VLAN that includes DHCP video server  316 , but does not include DHCP internet server  314 .  
         [0048]     Similarly, when the device is a personal computer, the port PT connected to the computer is associated with a VLAN that includes DHCP internet server  314 , but does not include DHCP video server  316 . As a result, the addressed data packet that includes the DHCP IP address request can only go to the correct DHCP server.  
         [0049]     Output circuit  422  forwards the addressed data packet to modem circuit  412  which, in turn, outputs the data packet signal to bridge BR 1  shown in  FIG. 3 . Bridge BR 1  determines the destination address, and forwards the data packet to edge device ED 1  and bridges BR 2 -BRn. Edge device ED 1  receives the data packet, converts the data packet into ATM data cells, and forwards the cells to switch AT 1 .  
         [0050]     Switch AT 1  examines the VCI in the header, and routes the cell to one of a number of ATM switches based on the VCI. Each succeeding ATM switch that receives the cell repeats the process until the cell reaches its destination. The examination and routing is performed in hardware without software support.  
         [0051]     In the present example, switch AT 1  forwards the cells to switch AT 3 . Edge device ED 3  converts the data cells received by switch AT 3  into a local data format, and passes the data onto DHCP video server  316 . Video server  316  outputs a response back to the device that includes IP address and boot up information (in addition to other information). (A similar process occurs when a personal computer boots up for network access.)  
         [0052]     In addition to providing a network architecture that supports a dynamic protocol, network architecture  300  of the present invention also reduces collisions on the network. This is because video traffic and data traffic are mapped to separate VLANs which are separate collision domains.  
         [0053]     In an alternate embodiment of the present invention, in addition to mapping different types of service (e.g., set top boxes and internet) to different VLANS, bridge circuit  410  also maps different classes of service to different VLANs. For example, IP address requests from a set top box ST can be mapped to a VLAN that provides the highest quality of service, while IP address requests from a personal computer for internet service can be mapped to a VLAN to provides a much lower quality of service. This is important when users wish to give priority to the video as opposed to, for example, internet e-mail traffic.  
         [0054]     It should be understood that various alternatives to the method of the invention described herein may be employed in practicing the invention. Thus, it is intended that the following claims define the scope of the invention and that methods and structures within the scope of these claims and their equivalents be covered thereby.