Patent Publication Number: US-2007104189-A1

Title: Network system and operation method thereof

Description:
FIELD OF THE INVENTION  
      The invention relates to network systems, and particularly to a network system and an operation method thereof.  
     DESCRIPTION OF THE RELATED ART  
      With the rapid development of network systems, network devices, such as routers, switches etc. often have a spare/backup function to ensure operating stability of the network devices. Conventionally, the network device comprises a primary control card for processing and exporting data packets via some uplink ports of the network device, and a secondary control card used as a spare/backup one for processing and exporting the data packets. The secondary control card processes and exports the data packets via other uplink ports of the network device only if the primary control card has malfunctioned. That is, only one part of the uplink ports of the network device can export data packets. Therefore, transmission of the data packets is slow.  
      Therefore, a heretofore unaddressed need exists in the industry to overcome the aforementioned deficiencies and inadequacies.  
     SUMMARY OF THE INVENTION  
      An exemplary embodiment of the invention provides a network system. The network system includes a client device, a central office, and a network device connected to the client device and the central office. The network device includes a first control card, a second control card, and a plurality of line cards connected to the first control card, the second control card, and the client device. Connections between the first control card and one part of the line cards are designated as primary connections, and connections between the second control card and the same part of the line cards are designated as redundant connections. Meanwhile, connections between the second control card and a remaining part of the line cards are designated as primary connections, and connections between the first control card and the remaining part of the line cards are designated as redundant connections.  
      Another exemplary embodiment of the invention provides an operation method of a network system. The operation method includes steps of: providing a first control card, a second control card, a backplane, and a plurality of line cards; establishing connections between the line cards and the first control card and the second control card; designating primary connections between the first control card and one part of the line cards, and redundant connections between the second control card and the same part of the line cards; designating primary connections between the second control card and a remaining part of the line cards, and redundant connections between the first control card and the remaining part of the line cards; and starting the primary connections.  
      Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings, in which: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a schematic view of a network system of an exemplary embodiment of the invention;  
       FIG. 2  is a block diagram of a network device of the network system of  FIG. 1 ; and  
       FIG. 3  is a flowchart of an operation method of the network of another exemplary embodiment of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
       FIG. 1  is an environment of a network system of an exemplary embodiment of the invention. A client device  10  is connected to a network device  30  via an asymmetrical digital subscriber loop transceiver unit-remote terminal (ATU-R)  20 . The network device  30  is in communication with a central office  50  via a network  40 . The network  40  may comprise any network known in the art, such as the Internet, an Intranet, a Fiber Channel network, Storage Area Network (SAN), Local Area Network (LAN), etc. In the exemplary embodiment, the client device  10  may be a personal computer, a personal digital assistant (PDA), and so on.  
       FIG. 2  is a block diagram of the network device  30  of the network system of  FIG. 1 . In the exemplary embodiment, the network device  30  comprises a plurality of line cards  100 , a backplane  200 , a first control card  300  and a second control card  400 . The backplane  200  connects the line cards  100  to the first control card  300  and the second control card  400 , and connects the first control card  300  to the second control card  400 . In the exemplary embodiment, the line cards  100  are consecutively labeled as a first line card, a second line card, . . . , and an nth line card.  
      The line cards  100  are connected to the client device  10  via the ATU-R  20  of  FIG. 1 , and connected to the first and second control cards  300 ,  400  via the backplane  200 . Each line card  100  comprises a downlink port  101  connected to the backplane  200  and the client device  10 . The downlink ports  101  receive data packets from the first control card  300 , the second control card  400 , and the client device  10 , and transmit data packets processed in the line cards  100  to the first control card  300 , the second control card  400 , and the client device  10 . In the exemplary embodiment, the downlink ports  101  of the line cards  100  are connected to the first control card  300  and the second control card  400  via the backplane  200 . The connections between odd-numbered line cards  100  and the first control card  300  are designated as primary connections, and the connections between the odd-numbered line cards  100  and the second control card  400  are designated as redundant connections. Meanwhile, the connections between even-numbered line cards  100  and the second control card  400  are designated as a primary connections, and the connections between the even-numbered line cards  100  and the first control card  300  are designated as redundant connections. Note that the primary and redundant connection settings can be reversed or altered by means of other rules.  
      The first control card  300  and the second control card  400  are connected to the central office  50  via the network  40 . The first control card  300  comprises two uplink ports  301 , two processing modules  305 , and a switch engine  303 . The uplink ports  301  receive data packets from the central office  50 , and transmit the data packets to the processing modules  305  respectively. The processing modules  305  process the data packets, and transmit the processed data packets to the switch engine  303 . The second control card  400  comprises two uplink ports  401 , two processing modules  405 , and a switch engine  403 . The uplink ports  401  receive the data packets from the central office  50 , and transmit the data packets to the processing modules  405  respectively. The processing modules  405  process the data packets, and transmit the processed data packets to the switch engine  403 . The switch engines  303  and  403  transmit the processed data packets to the corresponding line cards  100  or transmit the processed data packets to each other via the backplane  200 .  
      In alternative embodiments, the first control card  300  can comprise an uplink port  301  or a plurality of uplink ports  301 , and a processing module  305  or a plurality of processing modules  305 . Meanwhile, the uplink ports  301  can be connected to the processing modules  305  respectively, or the uplink ports  301  are connected to the processing module  305 . Correspondingly, the second control card  400  can comprise an uplink port  401  or a plurality of uplink ports  401 , and a processing module  405  or a plurality of processing modules  405 . Meanwhile, the uplink ports  401  can be connected to the processing modules  405  respectively, or the uplink ports  401  are connected to the processing module  405 .  
      For example, when the uplink ports  301  of the first control card  300  receive the data packets from the central office  50 , herein the data packets are designated as a first data packets, the processing modules  305  process the first data packet, and transmit the processed first data packets to the switch engine  303 . The switch engine  303  determines destination of the processed first data packets. If the destination is the client device  10 , the switch engine  303  transmits the processed first data packets to the line cards  100  via the backplane  200 . In the line cards  100 , the processed first data packets are further processed, and designated as second data packets. The downlink ports  101  of the line card  100  transmit the second data packets to the client device  10  via the ATU-R  20 . If the destination is another central office, the switch engine  303  transmits the processed first data packets to the switch engine  403  of the second control card  400 . Then, the processed first data packets are transmitted to the central office via the uplink ports  401  of the second control card  400 .  
      When the line card  100  receives data packets from the client device  10 , herein the data packets are designated as third data packets, the third data packets are processed in the line card  100 , and the processed third data packets are transmitted to the backplane  200  via the downlink port  101  of the line card  100  according to the primary connection. The backplane  200  transmits the processed third data packets to the switch engine  303  of the first control card  300 , and the switch engine  403  of the second control card  400 . In the processing modules  305  and  405 , the processed third data packets are further processed and designated as fourth data packets. Then, the uplink ports  301  and  401  transmit the fourth data packets to the central office  50 .  
      The first control card  300  further comprises a first monitoring module  304 , and the second control card  400  further comprises a second monitoring module  404 . The first monitoring module  304  and the second monitoring module  404  send “hello” messages to each other in an advance time period such as 3 seconds, to determine whether one of the first and second control cards  300 ,  400  has malfunctioned. For example, if the second monitoring module  404  does not receive “hello” message from the first monitoring module  304  over the advance time period, the second monitoring module  404  determines the first control card  300  has malfunctioned, and sends a message to the line cards  100 . When the odd-numbered line cards  100  receive the message, the odd-numbered line cards  100  close the primary connections, and start the redundant connections. Meanwhile, the second control card  400  automatically replaces the first control card  300 , and informs the network system to close the uplink ports  301  of the first control card  300 . Similarly, if the first monitoring module  304  does not receive “hello” message from the second monitoring module  404  over the advance time period, the first control card  300  automatically replaces the second control card  400 , and the uplink ports  401  of the second control card  400  are closed.  
       FIG. 3  is a flowchart of an operation method of the network system. In step S 301 , a first control card  300 , a second control card  400 , a backplane  200  and a plurality of line cards  100  are provided. In step  303 , the backplane  200  establishes connections among the line cards  100  and the first control card  300 , and the second control card  400 . In step  305 , the connections between the first control card  300  and one part of the line cards  100  are designated as primary connections, and the connections between the second control card  400  and the same part of the line cards  100  are designated as redundant connections. In step  307 , the connections between the second control card  400  and a remaining part of the line cards  100  are designated as primary connections, and the connections between the first control card  300  and the remaining part of the line cards  100  are designated as redundant connections. In the exemplary embodiment, the line cards  100  are consecutively labeled as a first line card, a second line card, . . . , and a nth line card. Connections between the first control card  300  and odd-numbered line cards  100  are designated as primary connections, and connections between the odd-numbered line cards  100  and the second control card  400  are designated as redundant connections. Connections between the second control card  300  and even-numbered line cards  100  are designated as primary connections, and connections between the even-numbered line cards  100  and the first control card  300  are designated as redundant connections. Note that the primary and redundant connection settings can be reversed. In step  309 , the primary connections are started.  
      In step  311 , a first monitoring module  304  of the first control card  300  and a second monitoring module  404  of the second control card  300  cooperatively determine whether one of the first control card  300  and the second control card  400  has malfunctioned. If messages can be successfully delivered between the first monitoring module  304  and the second monitoring module  404 , the network system is maintained in the primary connection (in step  309 ). In step  313 , if one of the first control card  300  and the second control card  400  has malfunctioned, for example, the first control card  300  has malfunctioned, the second control card  400  sends a message to the line cards  100 . In step  315 , after the line cards  100  receive the message, the primary connections between the first control card  300  and the odd-numbered line cards  100  are closed, and the redundant connections between the second control card  400  and the odd-numbered line cards  100  are started. That is, the second control card  400  replaces the first control card  300 , and the uplink ports  301  of the first control card  300  are closed.  
      Alternatively, if the second control card  400  has malfunctioned, in step  313  again, the first control card  300  sends a message to the line cards  100 . In step  315 , after the line cards  100  receive the message, the primary connections between the second control card  400  and the even-numbered line cards  100  are closed, and the redundant connections between the first control card  300  and the even-numbered line cards  100  are started. That is, the first control card  300  replaces the second control card  400 , and uplink ports  401  of the second control card  400  are closed.  
      Because the uplink ports  301 ,  401  and the switch engines  303 ,  403  are effectively employed, the data packets can be quickly processed and transmitted in the network system.  
      Note that the number of line cards in each group is not required to be equal. In an alternative embodiment, the line cards  100  are categorized into primary line cards  100  and secondary line cards  100  at will. The connections between the primary line cards  100  and the first control card  300  are designated as primary connections, and the connections between the primary line cards  100  and the second control card  400  are designated as redundant connections. Meanwhile, the connections between the secondary line cards  100  and the second control card  400  are designated as primary connections, and the connections between the secondary line cards  100  and the first control card  400  are designated as redundant connections.  
      While embodiments and methods of the present invention have been described above, it should be understood that they have been presented by way of example only and not by way of limitation. Thus the breadth and scope of the present invention should not be limited by the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.