JP2012222790A - Communication system, switching device, and relay device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology that can constantly monitor the transmission quality of a network without using a test frame and the like.SOLUTION: A plurality of switching devices accommodating a user terminal and at least one relay device are disposed on a network. A switching device receives a frame signal including data transmitted by a user terminal, stores a first error detection code added to the frame signal as tag information in the frame signal, and transmits the frame signal to the network. Also, the switching device receives a frame signal from the network, detects whether or not transmission abnormality has occurred between the own device and a transmission source switching device based on the first error detection code stored in the received frame signal and a second error detection code calculated based on the frame signal; and if transmission abnormality has been detected, discards the frame signal, and if transmission abnormality has not been detected, transmits the frame signal to an accommodated transmission destination user terminal.

Description

  The present invention relates to a communication system, a switching device, and a relay device that can transmit and receive data between user terminals via a network.

  Conventionally, in order to transmit and receive data between user terminals via a network with high reliability, various techniques for managing transmission quality in the network have been developed.

  For example, the relay device sends a test frame for conducting a continuity characteristic test between the user access devices facing each other on the network, and calculates the throughput and delay time between the user access devices, thereby the end of the network. There is a technique for managing transmission quality in End (for example, see Patent Document 1).

JP 2010-130479 A

  However, since the conventional technique uses a test frame, the throughput and delay time can be obtained only when the test frame is transmitted, and the transmission quality of the network cannot be constantly monitored.

  In view of the problems of the prior art, an object of the present invention is to provide a technique that can constantly monitor the transmission quality of a network without using a test frame or the like.

  In order to solve the above-described problem, a communication system according to the present invention includes a plurality of switching devices accommodating user terminals and at least one relay device arranged on a network, and data transmission between user terminals accommodated in different switching devices. In the communication system that performs transmission and reception, the switching device includes a terminal reception unit that receives a frame signal having data transmitted from a user terminal accommodated therein, and a first error detection code added to the frame signal as tag information. As a frame signal, a network transmission unit for transmitting the frame signal to the network, a network reception unit for receiving the frame signal from the network, and a first error code stored in the frame signal received by the network reception unit; Source switching based on the second error detection code calculated based on the frame signal If a transmission error is detected, a detection unit that discards the frame signal is detected, and if no transmission error is detected by the detection unit, the frame signal is accommodated. A terminal transmission unit that transmits to a user terminal as a transmission destination.

  In addition, a monitoring device that is arranged on the network and controls and monitors the operation of a plurality of switching devices and relay devices is provided, and the detection unit counts the number of discarded frame signals for each switching device of the transmission source, and switches the transmission source. When the number of discarded frame signals in the apparatus exceeds a predetermined number, the detected transmission abnormality may be notified to the monitoring apparatus as being caused by a failure occurring in the transmission source switching apparatus.

  The terminal reception unit further includes a plurality of input ports that receive frame signals from the user terminal, and the network transmission unit adds information on the input ports that have received the frame signals to the frame signals as tag information, and a detection unit The number of discarded frame signals is counted for each input port of the transmission source switching device based on the input port information added to the frame signal, and the number of discarded frame signals at the input port of the transmission source switching device is counted. When the number exceeds a predetermined number, data transmission / reception with the input port of the transmission source switching device may be blocked.

  The switching device also includes a time information storage unit that stores the transmission time of the frame signal transmitted by the network transmission unit in the frame signal as tag information, and a transmission time stored in the frame signal received by the network reception unit. And a time measuring unit that measures a transmission time during which the frame signal is transmitted to and from the transmission source switching device, and the detection unit may detect a transmission abnormality based on the measured transmission time.

  The time measurement unit measures the transmission time for each switching device at the transmission source, and the detection unit detects the detected transmission abnormality when the transmission time at the transmission source switching device exceeds a predetermined time. The monitoring apparatus may be notified of the occurrence of congestion with the switching apparatus.

  In addition, the time measuring unit measures the transmission time for each input port of the transmission source switching device, and the detection unit detects when the transmission time at the input port of the transmission source switching device is equal to or longer than a predetermined time. Transmission / reception of data to / from the input port of the transmission source switching device may be blocked because the transmission abnormality is caused by congestion occurring with the input port of the transmission source switching device.

  The relay apparatus may include a relay reception unit that receives a frame signal from the network and a relay transmission unit that transmits the frame signal to the network.

  In addition, the relay reception unit may detect a transmission abnormality with the transmission destination device of the frame signal based on the received frame signal and notify the monitoring device.

  The switching device according to the present invention is arranged on a network together with at least one relay device to constitute a communication system, and performs switching between transmitting and receiving data between a user terminal accommodated and a user terminal accommodated in another switching device. A terminal receiving unit that receives a frame signal having data transmitted from a user terminal accommodated therein, and stores the first error detection code added to the frame signal in the frame signal as tag information; Calculated based on a network transmitter that transmits a signal to the network, a network receiver that receives a frame signal from the network, and the first error code and the frame signal stored in the frame signal received by the network receiver Whether or not a transmission error has occurred with the transmission source switching device based on the second error detection code A detection unit that detects and detects a transmission abnormality, and a terminal transmission unit that transmits a frame signal to a destination user terminal when a transmission abnormality is not detected by the detection unit. Prepare.

  The relay device according to the present invention is arranged on a network together with a plurality of switching devices accommodating user terminals to form a communication system, and relays data transmitted and received between user terminals accommodated in different switching devices. A relay device, comprising: a relay receiving unit that receives a frame signal having data from the network; and a relay transmitting unit that transmits the frame signal to the network.

  According to the present invention, the transmission quality of a network can be constantly monitored without using a test frame or the like.

The block diagram which shows an example of a structure of the communication system 100 which concerns on one Embodiment. Block diagram showing an example of the configuration of the edge switch 3 The figure which shows an example of a mode that a structure of a frame changes according to transmission Block diagram showing an example of the configuration of the relay device 4 The flowchart which shows an example of the operation process by the communication system 100 which concerns on one Embodiment. Block diagram showing another example of the configuration of the communication system

  FIG. 1 is a block diagram showing an example of a configuration of a communication system 100 according to an embodiment of the present invention.

  In the communication system 100 of this embodiment, a monitoring control server 2, edge switches 3 a and 3 b, and a relay device 4 are arranged on a network 1. It is assumed that the network 1 of the present embodiment is a wide area ether network.

  The monitoring control server 2 can be a general computer or the like, and monitors and controls the operations of the edge servers 3 a and 3 b and the relay device 4 arranged on the network 1.

  The edge switches 3a and 3a are LAN switches such as layer 2 switches that connect between the user terminals 5-1 to 5-M and 6-1 to 6-N accommodated therein and the network 1 (M, N is a natural number of 1 or more). 1 are directly connected to the user terminals 5-1 to 5-M and 6-1 to 6-N, they may be connected via a router or the like. The user terminals 5-1 to 5-M and 6-1 to 6-N in the present embodiment are computers, data servers, and the like.

  FIG. 2 is a block diagram showing the configuration of the edge switches 3a and 3b. The edge switches 3a and 3b receive Ethernet frames having data transmitted from the user terminals 5 and 6 at a plurality of input ports of a receiving unit on the terminal side (not shown), and the FCS check unit 10 and network information After processing by the adding unit 11, time stamp adding unit 12, switching unit 13, and FCS recalculation unit 14, the frame is transmitted to the network 1. At the same time, the edge switches 3a and 3b receive the frame transmitted from the network 1, and perform processing by the FCS check unit 15, the switching unit 16, the delay measurement unit 17, the network information analysis unit 18, and the FCS recalculation unit 19. Then, the frame is transmitted to the user terminals 5 and 6 that are transmission destinations.

  For example, when a frame (FIG. 3 a) transmitted from the user terminal 5 or 6 is input, the FCS check unit 10 removes an FCS (Frame Check Sequence) field added to the frame from the frame and sets the value of the FCS field. To get. The FCS check unit 10 calculates, for example, a CRC (Cyclic Redundancy Check) value using each field of the frame from which the FCS field is removed, and the CRC value and the FCS field value (first error detection code). And compare. The FCS check unit 10 detects whether or not a transmission error such as a bit error of data generated during transmission has occurred in the received frame. The FCS check unit 10 outputs a frame having no FCS field to the network information adding unit 11 when no transmission error has occurred. On the other hand, when the FCS check unit 10 detects a transmission error, the FCS check unit 10 discards the frame.

  In the frame shown in FIG. 3, the preamble field allows each apparatus to recognize the start of frame transmission and gives a timing for synchronization. Further, the source and destination MAC addresses are set and stored in the SA and DA fields, and the data transmitted by the user terminal is stored in the data field.

  The network information adding unit 11 adds information for monitoring the transmission quality within the network 1, that is, between the edge switches 3a-3b, to the frame as a tag of port information. Specifically, the network information adding unit 11 of the present embodiment uses the FCS check unit 10 together with information such as the IP address of the edge switch 3, the host name, and the input port number to which the transmission source user terminal is connected. The value of the removed FCS field is added as a tag of port information. Further, in the frame transmission in the network 1 of the present embodiment, it is assumed that the VLAN service is used, and the network information adding unit 11 adds information for this to the frame as a carrier VLAN tag.

  The time stamp adding unit 12 (time information storage unit) is not used in order to cause the delay measuring unit 17 (time measuring unit) of the destination edge switch 3 to be described later to measure the delay time that is the transmission time in the network 1. Based on the clock signal output from the illustrated clock, the frame transmission time is added to the frame as a time stamp tag.

  The switching unit 13 can appropriately use a layer 2 switch or the like, and performs a switching operation based on the SA and DA fields of the frame. The switching unit 16 performs the same operation as the switching unit 13. In the present embodiment, the two switching units 13 and 16 are arranged, but one switch may be operated as the switching units 13 and 16.

  The FCS recalculation unit 14 recalculates the value of the FCS field and adds it to the frame using the tags newly added by the network information addition unit 11 and the time stamp addition unit 12 together with each field of the frame (FIG. 3). (B)). The FCS recalculator 14 transmits the frame shown in FIG. In FIG. 3B, the recalculated FCS field is indicated as FCS ′. The FCS recalculator 14 constitutes a network transmitter together with the network information adder 11 and the time stamp adder 12.

  The FCS check unit 15 receives a frame from the network 1 as a network reception unit and removes the added FCS field. The FCS check unit 15 outputs the frame from which the FCS field has been removed to the switching unit 16. However, like the FCS check unit 10, the FCS check unit 15 of the present embodiment acquires the value of the FCS field and calculates the CRC value using fields and tags other than the FCS field of the frame. The FCS check unit 15 compares the CRC value with the FCS field value and detects whether or not a transmission error has occurred in the received frame. However, unlike the FCS check unit 10, the FCS check unit 15 does not discard the frame for processing by the subsequent network information analysis unit 18 even when a transmission error is detected.

  The delay measuring unit 17 acquires the transmission time in the source edge switch 3 from the frame time stamp tag, and compares it with a clock signal output by a clock (not shown) of its own edge switch 3. The delay measuring unit 17 measures a delay time that is a frame transmission time in the network 1. Thereby, the congestion state etc. in the network 1, especially between the edge switches 3 can be detected.

  The network information analysis unit 18 (detection unit) uses the determination result of the FCS check unit 15 and the measurement result of the delay measurement unit 17 together with the port information and the carrier VLAN tag information in the received frame. Monitor transmission quality.

  Specifically, the network information analysis unit 18 acquires information on the source edge switch 3 and the input port number from the port information and the tag of the carrier VLAN in the received frame. The network information analysis unit 18 calculates a CRC value (second error detection code) using a field other than the tag among the frames from which the FCS field is removed, and calculates the CRC value and the FCS field at the time of frame transmission. Compare the value. If the values are different from each other, the network information analysis unit 18 determines that the frame is broken at the time of transmission due to a failure in the source edge switch 3 or the like, and discards the frame. The network information analysis unit 18 monitors the state of the source edge switch 3 by counting the number of frames discarded for each of the source edge switch 3 and the input port and generating a frequency distribution or the like. On the other hand, the network information analysis unit 18 outputs the frame to the FCS recalculation unit 19 when the value of the FCS field at the time of frame transmission matches the CRC value.

  Here, since the network 1 of the present embodiment is a wide area Ethernet network, each edge switch 3 does not transmit a frame only to the destination edge switch 3, but is arranged on the network 1. To the edge switch 3. As a result, the network information analysis unit 18 of each edge switch 3 can generate the frequency distribution of the source edge switch 3 and its input ports, and the state of the source edge switch 3 for each input port. That is, monitoring can be performed in units of input routes.

  In addition, when a transmission error is detected by the FCS check unit 15, the network information analysis unit 18 counts the number of transmission errors with the opposing relay device 4, for example, to transmit to the relay device 4. Monitor road conditions.

  Furthermore, the network information analysis unit 18 according to the present embodiment obtains an average value, a maximum value, a minimum value, and the like of the delay time for each of the source edge switch 3 and its input port by the delay measurement unit 17, and based on those values. Then, the state of the transmission line connecting the source edge switch 3 is monitored for each input port.

  Based on the above monitoring operation, the network information analysis unit 18, for example, when the number of discarded frames becomes a predetermined number α or more, the control edge monitoring switch 2 has a failure in the source edge switch 3. Notify that it has occurred. By displaying an alarm based on the notification, the control monitoring server 2 can promptly restore the source edge switch 3 based on the alarm, and improve the quality of the communication system 100. Can be secured. Alternatively, when the number of discarded frames from the predetermined input port of the source edge switch 3 is equal to or greater than the predetermined number α, the network information analysis unit 18 uses the known input port to The communication may be blocked. Thereby, the edge switch 3 can notify the transmission quality to the user of each user terminal accommodated. Then, these user terminals can switch to a network for bypass diversity and the like, and can continue to transmit data.

  In addition, when the number of transmission errors with the relay device 4 exceeds the predetermined number β, the network information analysis unit 18 notifies the control monitoring server 2 that a failure has occurred in the transmission path. By displaying an alarm based on the notification, the control monitoring server 2 can promptly restore the transmission path based on the alarm, and ensure the quality of the communication system 100. it can.

  Furthermore, when the delay time with the predetermined input port of the source edge switch 3, for example, the average value of the delay time becomes equal to or greater than the predetermined delay time t, the network information analyzing unit 18 Then, it is notified that congestion has occurred in the transmission line connecting the predetermined input port of the edge switch 3a. The control and monitoring server 2 displays an alarm based on the notification, so that the administrator can respond to avoiding congestion based on the alarm, for example, a predetermined input port of the source edge switch 3 and Thus, it is possible to promptly take measures such as changing the transmission path connecting the two, and the quality of the communication system 100 can be ensured. Alternatively, the network information analysis unit 18 may block communication with a predetermined input port of the source edge switch 3 in a congested state using a known method. Thereby, the edge switch 3 can notify the transmission quality to the user of each user terminal accommodated. Then, these user terminals can switch to a network for bypass diversity and the like, and can continue to transmit data.

  The FCS recalculation unit 19 (terminal transmission unit) performs the same operation as the FCS recalculation unit 14. However, the FCS recalculation unit 19 removes the port information, time stamp, and carrier VLAN tags, and recalculates using the same fields of the remaining frames as before transmission (FIG. 3D).

  The relay device 4 is a core switch or the like that relays a frame transmitted in the network 1, and includes an FCS check unit 20, a switching unit 21, and an FCS recalculation unit 22 as shown in FIG.

  Similar to the FCS check unit 15, the FCS check unit 20 (relay receiving unit) receives the frame shown in FIG. The FCS check unit 20 removes the FCS field added to the frame and acquires the value of the FCS field. The FCS check unit 20 calculates the CRC value using the field and tag of the frame from which the FCS field is removed, compares the CRC value with the FCS field value, and determines whether or not a transmission error has occurred in the received frame. To detect. However, the FCS check unit 20 of the present embodiment does not discard the frame for processing by the network information analysis unit 18 of the destination edge switch 3 even if a transmission error is detected.

  The switching unit 21 can appropriately use a known layer 3 switch or the like, and performs a switching operation based on the SA and DA fields of the frame.

  The FCS recalculation unit 22 (relay transmission unit) recalculates the value of the FCS field and adds it to the frame using each field and tag of the frame from which the FCS field is removed as shown in FIG. c)). In FIG. 3C, the recalculated FCS field is indicated as FCS ".

  Next, an operation procedure in the communication system 100 of the present embodiment will be described with reference to the flowchart shown in FIG. In the following, a case where data is transmitted from the user terminal 5-1 to the user terminal 6-1 will be described as an example. However, the same applies to transmission / reception of data between the other user terminals 5 and the user terminal 6. There is no explanation.

  Specifically, when the user terminal 5-1 receives a data transmission instruction from the user via an input device (not shown), the user terminal 5-1 selects an address that is the transmission source and the user terminal 6-1 as the transmission destination. A frame in which data is stored in the DA field and data is stored in the data field is generated (FIG. 3A). The user terminal 5-1 transmits the generated frame to the edge switch 3a. The edge switch 3a receives a frame from the input port to which the user terminal 5-1 is connected, and starts processing from step S10.

  Step S10: The FCS check unit 10 of the edge switch 3a removes the FCS field added to the frame from the frame received from the user terminal 5-1, and acquires the value of the FCS field.

  Step S11: The FCS check unit 10 calculates a CRC value using each field of the frame from which the FCS field is removed in Step S10, and compares the CRC value with the FCS field value. The FCS check unit 10 detects whether or not a transmission error has occurred in the received frame. If no transmission error is detected, the FCS check unit 10 proceeds to step S12 (NO side). On the other hand, when detecting a transmission error (YES side), the FCS check unit 10 discards the frame and ends the series of processes.

  Step S12: The network information adding unit 11 of the edge switch 3a includes the IP address of the edge switch 3a, the host name, the input port number to which the user terminal 5-1 is connected, and the value of the FCS field removed by the FCS check unit 10. Is added as a tag of port information. Further, the network information adding unit 11 also adds a carrier VLAN tag to the frame.

  Step S13: The time stamp adding unit 12 of the edge switch 3a adds the frame transmission time to the frame as a time stamp tag based on a clock signal output from a clock (not shown).

  Step S14: The switching unit 13 of the edge switch 3a performs switching so as to transmit the frame to the user terminal 6-1 based on the values of the SA and DA fields of the frame.

  Step S15: The FCS recalculation unit 14 of the edge switch 3a recalculates the value of the FCS field using each field of the frame and the tag added by the network information addition unit 11 and the time stamp addition unit 12, and FCS ′ To the frame. The FCS recalculator 14 transmits the frame shown in FIG.

  Step S16: The relay device 4 relays the frame transmitted from the edge switch 3a to the edge switch 3b that accommodates the destination user terminal 6-1. Specifically, the FCS check unit 20 receives the frame shown in FIG. 3B from the network 1 and removes the added FCS field. The FCS check unit 20 outputs the frame from which the FCS field has been removed to the switching unit 21.

  The FCS check unit 20 acquires the value of the removed FCS field, calculates the CRC value using each field of the frame other than the FCS field, and compares the value of the FCS field with the CRC value. Thus, it is preferable to detect whether or not a transmission error has occurred in the received frame. When the FCS check unit 20 detects a transmission error, it is preferable to count the number of transmission errors as an error in the transmission path to the source edge switch 3a, and the number of transmission errors is equal to or greater than a predetermined number. In this case, it is preferable to notify the control monitoring server 2 that a failure has occurred in the transmission path. Thereby, when the control monitoring server 2 displays an alarm based on the notification, the administrator can quickly restore the transmission path, and can ensure the quality of the communication system 100.

  On the other hand, the switching unit 21 switches the frame output from the FCS check unit 20 based on the SA and DA fields, and the FCS check unit 22 selects the frame from which the FCS field shown in FIG. Using each field and tag, the value of the FCS field is recalculated and added to the frame as FCS ″ (FIG. 3C). The FCS check unit 22 adds the frame shown in FIG. Send.

  Step S17: The FCS check unit 15 of the edge switch 3b receives the frame shown in FIG. 3C from the network 1 and removes the added FCS field. The FCS check unit 15 outputs the frame from which the FCS field has been removed to the switching unit 16. At the same time, the FCS check unit 15 acquires the value of the FCS field and calculates the CRC value using each field and tag of the frame from which the FCS field is removed. The FCS check unit 15 detects whether a transmission error has occurred in the received frame from the comparison between the CRC value and the FCS field value, and outputs the result to the network information analysis unit 18.

  Step S18: The switching unit 16 of the edge switch 3b switches to transmit data to the user terminal 6-1 based on the values of the SA and DA fields of the frame.

  Step S19: The delay measuring unit 17 of the edge switch 3b acquires the transmission time from the frame time stamp tag, and compares it with a clock signal output by a clock (not shown) of its own edge switch 3b. The delay measuring unit 17 measures a delay time between the edge switches 3a-3b.

  Step S20: The network information analysis unit 18 of the edge switch 3b acquires information on the source edge switch 3a and the input port from the port information and the carrier VLAN tag in the frame. The network information analysis unit 18 calculates a CRC value using a field other than the tag in the frame from which the FCS field is removed, and compares the value of the FCS field at the time of frame transmission with the CRC value. When the values are different from each other, the network information analysis unit 18 determines that the frame is broken at the time of transmission due to a failure in the source edge switch 3a, and discards the frame. The network information analysis unit 18 counts the number of discarded frames for each edge switch 3a and each input port, generates a frequency distribution and the like, and monitors the state of the edge switch 3a for each input port. On the other hand, the network information analysis unit 18 outputs the frame to the FCS recalculation unit 19 when the value of the FCS field at the time of frame transmission matches the CRC value.

  Further, when a transmission error is detected by the FCS check unit 15, the network information analysis unit 18 counts the number of transmission errors with the relay device 4, for example, and determines the state of the transmission path with the relay device 4. Monitor.

  Further, the network information analysis unit 18 obtains an average value of the delay time for each edge switch 3a and its input port by the delay measurement unit 17, and based on the average value, determines the state of the transmission path connecting to the edge switch 3a. Monitor for each input port.

  Step S21: The network information analysis unit 18 of the edge switch 3b performs a quality management process for the network 1 based on the monitoring of the network 1 in step S20.

  Specifically, the network information analysis unit 18 notifies the control monitoring server 2 that a failure has occurred in the edge switch 3a when the number of discarded frames exceeds a predetermined number α. The control monitoring server 2 displays an alarm based on the notification and the administrator recovers the failure of the edge switch 3a based on the alarm. Alternatively, when the number of discarded frames from the predetermined input port of the edge switch 3a is equal to or greater than the predetermined number α, the network information analysis unit 18 communicates with the predetermined input port using a known method. The transmission quality is notified to each user of the user terminals 6-1 to 6-N that are blocked and accommodated. Then, the user terminals 6-1 to 6-N switch to a bypass diversity network or the like and continue data transmission.

  Further, the network information analysis unit 18 indicates that a failure has occurred in the transmission path with respect to the control monitoring server 2 when the number of transmission errors in the transmission path with the relay device 4 exceeds a predetermined number β. Notice. The control monitoring server 2 displays an alarm based on the notification and the administrator recovers the transmission path failure based on the alarm.

  Further, the network information analyzing unit 18 transmits a transmission path connecting the control switch server 2 to the edge switch 3a when the average delay time with the predetermined input port of the edge switch 3a is equal to or longer than the predetermined time t. To notify that congestion has occurred. The control monitoring server 2 displays an alarm based on the notification and the administrator avoids congestion by changing the transmission path with the edge switch 3a based on the alarm. Alternatively, the network information analysis unit 18 blocks each communication with a predetermined input port of the edge switch 3a in a congested state by using a known method, and each user of the user terminals 6-1 to 6-N accommodates the user. Is notified of the transmission path quality. Then, the user terminals 6-1 to 6-N switch to a bypass diversity network or the like and continue data transmission.

  Step S22: The FCS recalculator 19 of the edge switch 3b removes the tag of the port information, time stamp, and carrier VLAN, calculates the value of the FCS field using the same remaining frame field as before transmission, and adds it to the frame. To do. The FCS recalculator 19 outputs the frame shown in FIG. 3D toward the user terminal 6-1.

  As described above, in this embodiment, the network information adding unit 11 of the source edge switch 3 adds the FCS field value of the frame transmitted from the user terminal to the port information tag and holds it, thereby performing the test. The transmission quality of the network 1 can be constantly monitored without using a frame or the like.

  The time stamp adding unit 12 adds the transmission time as a time stamp tag, so that the transmission quality between the network 1, particularly the edge switch 3, can be constantly monitored without using a test frame or the like.

  Further, the FCS check unit 20 of the relay device 4 and the FCS check unit 15 of the edge switch 3 count the number of transmission errors for each source edge switch 3 without discarding the frame, and the network information analysis unit of the edge switch 3 18 compares the value of the FCS field in the source edge switch 3 added to the tag of the port information of the frame with the CRC value calculated from the received frame, and the received frame is broken. Therefore, it is possible to determine whether the cause is a failure of the source edge switch 3 or a transmission error in the transmission path, and finer quality control of the communication system 100 is possible.

Further, since the network information analysis unit 18 has an input port blocking function, transmission quality can be notified to the end user.
<< Additional items of embodiment >>
1) In the above embodiment, two edge switches 3 and one relay device 4 are used as shown in FIG. 1, but the present invention is not limited to this, and two or more like the communication system shown in FIG. The edge switch 3 and the relay device 4 may be arranged on the network 1.

  2) In the above embodiment, congestion in the transmission line is detected based on a comparison between the average value of the measured delay times and the predetermined time t, but the present invention is not limited to this. For example, the detection may be performed based on a comparison between a maximum value or a minimum value of the measured delay time and a predetermined time. In addition, the average value, maximum value and minimum value of the measured delay time are compared with a predetermined time, and the CoS (Class of Service) and ToS (Type of Service) values of the frame are referred to for each class. You may detect the congestion in a transmission line.

  3) In the above embodiment, as shown in FIGS. 2 and 4, the edge switch 3 and the relay device 4 have different configurations, but the present invention is not limited to this. For example, the FCS check unit 10 of the edge switch 3 is operated as the FCS check unit 20, and the operations of the network information addition unit 11, the time stamp addition unit 12, the delay measurement unit 17, and the network information analysis unit 18 are invalidated and passed through the frame. The setting to be performed may be performed on the command line, and the edge switch 3 may be operated as the relay device 4.

  4) In the above embodiment, FCS is used as the error detection code. However, the present invention is not limited to this, and values of other error detection codes may be used.

  5) In the above embodiment, the FCS check unit 20 counts the number of transmission errors in the transmission path to the source edge switch 3a, but the present invention is not limited to this. For example, when the relay device 4 is connected in multiple stages, the number of transmission errors in the transmission path to the transmission source relay device may be counted.

  From the above detailed description, features and advantages of the embodiments will become apparent. It is intended that the scope of the claims extend to the features and advantages of the embodiments as described above without departing from the spirit and scope of the right. Further, any person having ordinary knowledge in the technical field should be able to easily come up with any improvements and modifications, and there is no intention to limit the scope of the embodiments having the invention to those described above. It is also possible to use appropriate improvements and equivalents within the scope disclosed in.

DESCRIPTION OF SYMBOLS 1 Network, 2 Control monitoring server, 3a-3c Edge switch, 4 Relay device, 5-1-5-M, 6-1-6-N User terminal 10, 15, 20 FCS check part, 11 Network information addition part , 12 Time stamp adding unit, 13, 16, 21 Switching unit, 14, 19, 22 FCS recalculation unit, 100 Communication system

Claims (10)

A communication system in which a plurality of switching devices accommodating user terminals and at least one relay device are arranged on a network, and data is transmitted and received between user terminals accommodated in different switching devices,
The switching device is
A terminal receiver for receiving a frame signal having data transmitted from the user terminal to be accommodated;
A network transmission unit that stores the first error detection code added to the frame signal as tag information in the frame signal, and transmits the frame signal to the network;
A network receiver for receiving the frame signal from the network;
Based on the first error code stored in the frame signal received by the network reception unit and the second error detection code calculated based on the frame signal, between the switching device of the transmission source And detecting whether or not a transmission abnormality has occurred, and when detecting the transmission abnormality, a detection unit that discards the frame signal;
A communication system comprising: a terminal transmission unit configured to transmit to a user terminal that is a transmission destination that accommodates the frame signal when the transmission abnormality is not detected by the detection unit. The communication system according to claim 1,
A monitoring device arranged on the network, for controlling and monitoring operations of the plurality of switching devices and the relay device;
The detection unit counts the number of discarded frame signals for each transmission source switching device, and detects when the number of discarded frame signals in the transmission source switching device exceeds a predetermined number. The communication system, wherein the monitoring apparatus is notified of the transmission abnormality as a result of a failure occurring in the transmission source switching apparatus. The communication system according to claim 2,
The terminal receiver is
A plurality of input ports for receiving the frame signal from the user terminal;
The network transmission unit adds the information of the input port that has received the frame signal to the frame signal as tag information,
The detection unit counts the number of discarded frame signals for each input port of the transmission source switching device based on the information of the input port added to the frame signal, and A communication system, wherein when the number of discarded frame signals at an input port exceeds a predetermined number, transmission / reception of the data to / from the input port of the transmission source switching device is blocked. The communication system according to claim 3,
The switching device is
A time information storage unit that stores the transmission time of the frame signal transmitted by the network transmission unit in the frame signal as tag information;
A time measuring unit that measures a transmission time during which the frame signal is transmitted to and from the transmission source switching device based on the transmission time stored in the frame signal received by the network receiving unit; ,
The said detection part detects the said transmission abnormality based on the measured said transmission time. The communication system characterized by the above-mentioned. The communication system according to claim 4,
The time measuring unit measures the transmission time for each switching device of the transmission source,
When the transmission time in the transmission source switching device is equal to or longer than a predetermined time, the detection unit determines that the detected transmission abnormality is caused by congestion occurring between the transmission source switching device and the monitoring device. A communication system characterized by notifying a device. The communication system according to claim 4,
The time measuring unit measures the transmission time for each input port of the transmission source switching device,
When the transmission time at the input port of the transmission source switching device is equal to or longer than a predetermined time, the detection unit detects that the detected transmission abnormality is congested with the input port of the transmission source switching device. The communication system is characterized by blocking transmission / reception of the data to / from an input port of the transmission source switching device. The communication system according to any one of claims 1 to 6,
The relay device is
A relay receiving unit for receiving the frame signal from the network;
A communication system comprising: a relay transmission unit that transmits the frame signal to the network. The communication system according to claim 7,
The relay receiving unit detects a transmission abnormality with a transmission destination device of the frame signal based on the received frame signal and notifies the monitoring device of the transmission abnormality. A switching device that is arranged on a network together with at least one relay device to form a communication system, and that transmits and receives data between a user terminal accommodated and a user terminal accommodated in another switching device,
A terminal receiver that receives a frame signal having data transmitted from the user terminal to be accommodated;
A network transmission unit that stores the first error detection code added to the frame signal as tag information in the frame signal, and transmits the frame signal to the network;
A network receiver for receiving the frame signal from the network;
Based on the first error code stored in the frame signal received by the network reception unit and the second error detection code calculated based on the frame signal, between the switching device of the transmission source And detecting whether or not a transmission abnormality has occurred, and when detecting the transmission abnormality, a detection unit that discards the frame signal;
When the transmission abnormality is not detected by the detection unit, a terminal transmission unit that transmits to a transmission destination user terminal that accommodates the frame signal;
A switching device comprising: A relay device that relays data transmitted and received between user terminals accommodated in different switching devices, comprising at least one switching device accommodating user terminals on a network to form a communication system,
A relay receiving unit for receiving a frame signal having the data from the network;
A relay transmitter that transmits the frame signal to the network;
A relay device comprising:

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