JP4473107B2 - Communication failure detection device - Google Patents

Description

  The present invention relates to a communication failure detection device that can detect a LAN line failure and an internal failure separately.

  With recent complications and sophistication of communication systems, many LAN (Local Area Network) line failures and in-device failures have occurred. For this reason, development of a technique for accurately detecting a LAN line failure or an in-device failure is underway.

  A communication apparatus connected to a LAN line and performing data communication includes, for example, a board (layer 1 processing board) that performs layer 1 processing depending on a transmission medium, and a board (layer 1 processing board that performs processing subsequent to layer 2 that does not depend on the transmission medium) Layer 2 processing board).

  Such a communication apparatus can accommodate various LAN lines by exchanging the layer 1 processing board. Further, as an interface between the layer 1 processing board and the layer 2 processing board, a media independent pendant interface (hereinafter referred to as MII (Medium Independent Interface)) which is a standard of IEEE (Institute of Electrical and Electronics Engineers) 802.3 standard. ) And Gigabit MII (hereinafter referred to as GMII). In-device (communication device) failures between boards connected by MII or GMII (layer 1 processing board and layer 2 processing board) are layer 2 media access control (hereinafter referred to as MAC (Media Access Control)). Can be detected using a frame check sequence (hereinafter referred to as FCS (Frame Check Sequence)).

  However, since the FCS error is detected by the line failure on the LAN line receiving side of the communication device, the conventional communication device monitoring method using the FCS has a problem that the LAN line failure and the in-device failure cannot be distinguished. Therefore, in order to distinguish between a LAN line failure and an in-device failure, there is a method in which a monitoring pattern of a communication device is inserted in the previous stage and this is verified in the subsequent stage.

  The failure detection system described in Patent Document 1 includes a plurality of first substrates connected in series to each other and a second substrate connected to the first substrate in the final stage, and the first substrate is Monitoring pattern generation means for generating a monitoring pattern for fault monitoring, and insertion of a monitoring pattern assigned to the own board among different monitoring pattern insertion areas provided for the input signals from the first board at the preceding stage Monitoring pattern insertion means for inserting the monitoring pattern generated by the monitoring pattern generation means into the area and outputting it to a subsequent substrate, and the second substrate is input from the first substrate of the final stage A monitoring pattern separation unit that collectively separates a plurality of monitoring patterns from an input signal, and a monitoring pattern inspection unit that tests whether the collectively separated monitoring patterns are normal.

Japanese Patent Laid-Open No. 11-203209

  However, the conventional technique requires a monitoring pattern insertion unit and a monitoring pattern inspection unit. For this reason, there has been a problem that the number of circuits in the communication device for performing failure detection increases and the communication device becomes large-scale.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a communication failure detection device capable of distinguishing and detecting LAN line failures and in-device failures with a simple configuration.

In order to solve the above-described problems and achieve the object, the present invention is a communication failure detection apparatus that detects a communication failure connected to a LAN line, and depends on a medium for a received frame received from the LAN line. Layer 1 processing means for performing layer 1 processing; line failure detection means for detecting a LAN line abnormality in the reception direction from the LAN line based on the received frame and generating line failure information related to the LAN line abnormality; The received frame from the line failure detection means performs processing subsequent to layer 2 independent of the medium, and detects an abnormality of the received frame based on a frame check sequence of the received frame, and relates to the abnormality of the received frame The layer 2 processing means for generating received frame abnormality information and the line failure detecting means Based on the line defect information and said received frame anomaly information generated at Layer 2 processing unit, the LAN line in the line defect information is normal, and if the received frame in the received frame anomaly information is abnormal Receiving-side fault detecting means for detecting that a fault has occurred in the apparatus and detecting a fault in the apparatus, and the line fault detecting means generates the line fault information when detecting the LAN line abnormality And the received frame in which the frame check sequence is misdirected is transmitted to the layer 2 processing means, and the reception side failure detecting means receives the line failure information via the layer 2 processing means. Is abnormal, the LAN line is abnormal, and the received frame is normal in the received frame abnormal information The case, and detects the device failure is determined that the device failed.

  According to the present invention, since the communication failure detection apparatus includes the line failure detection means, it is possible to detect line failure information by detecting a LAN line abnormality in the reception direction from the LAN line based on the received frame. In addition, since the communication apparatus includes the layer 2 processing unit, it is possible to detect an abnormality of the received frame based on the frame check sequence of the received frame and generate received frame abnormality information.

  According to the present invention, since an abnormality of the received frame is detected based on the line defect information and the received frame abnormality information, it is possible to detect an in-device failure in a simple configuration, distinguishing from the LAN line abnormality. Play.

  Embodiments of a communication apparatus (communication failure detection apparatus) according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
The communication device 1 according to the present invention distinguishes and detects a line failure and a device failure. That is, the communication device 1 detects that a failure has occurred due to a line failure caused by a LAN line connected to the communication device 1 and that a failure has occurred due to a line failure in the communication device 1.

  FIG. 1 is a block diagram showing the configuration of Embodiment 1 of the communication apparatus according to the present invention. In the figure, a communication apparatus 1 is a router, a switching hub, or the like connected to a communication network such as an Ethernet (registered trademark) line, and includes a plurality of layer 1 side boards and one layer 2 side board. Has been. Here, a case where the layer 1 side substrate is the layer 1 side substrate 21X and the layer 2 side substrate 21Y, and the layer 2 side substrate is the layer 2 side substrate 3 will be described.

  The layer 1 side substrate 21X and the layer 2 side substrate 21Y perform transmission / reception of a LAN line and a frame (information). Since the layer 1 side substrate 21X and the layer 2 side substrate 21Y have the same configuration, the layer 1 side substrate 21X will be described as an example here.

  The layer 1 side substrate 21X includes a layer 1 processing unit 41, a line failure detection unit 51, and a transmission side failure detection unit 61. The layer 1 processing unit 41 is connected to the line failure detection unit 51 through the interface A and is connected to the transmission side failure detection unit 61 through the interface D.

  The layer 1 processing unit 41 receives a frame from the LAN line, performs layer 1 processing such as electrical level conversion and code decoding on the received frame, and uses a frame format based on MII via the interface A. The frame is transmitted to the line defect detection unit 51. The layer 1 processing unit 41 performs layer 1 processing depending on a medium such as code encoding and electrical level conversion on the frame from the transmission side failure detection unit 61 and outputs the frame to the LAN line.

  The line defect detection unit 51 performs frame detection by preamble and FCS check by CRC (Cyclic Redundancy Check) -32 which is a cyclic redundancy check. The transmission side failure detection unit 61 checks the FCS attached to the frame by the layer 2 processing unit 7 and determines whether or not the FCS attached to the frame by the layer 2 processing unit 7 is abnormal. The transmission-side failure detection unit 61 transfers the frame to the layer 1 processing unit 41 via the interface D when determining that the FCS check result is normal.

  The line failure detection unit 51 is connected to the layer 2 processing unit 7 of the layer 2 side substrate 3 by the interface B, and the transmission side failure detection unit 61 is connected to the layer 2 processing unit of the layer 2 side substrate 3 by the interface C.

  The interfaces A, C, and D here are IEEE 802.3 standard MII full-duplex communication (communication system capable of simultaneously performing transmission and reception). Interface B is MII full-duplex communication processed by the line defect detection unit 51.

  The layer 2 side substrate 3 includes a layer 2 processing unit 7, a reception side failure detection unit 8, a device management unit 10, and a frame processing unit 9. The layer 2 processing unit 7 performs processing subsequent to layer 2 that does not depend on a medium, such as frame detection, FCS check, length check, and preamble removal, with respect to the frame from the layer 2 side substrate 3 transferred via the interface B. Do. The layer 2 processing unit 7 transmits the FCS check result by the layer 2 processing unit 7 and RX_ER, which will be described later, to the reception side failure detection unit 8. The layer 2 processing unit 7 transfers the received frame to the frame processing unit 9 when the received frame is normally checked, and discards the received frame when there is some abnormality in the received frame. The reception-side failure detection unit 8 stores failure detection determination condition information 95, which will be described later, and distinguishes and detects line failures and in-device failures based on the failure detection determination condition information 95.

  The device management unit 10 is connected to the reception side failure detection unit 8, the layer 2 processing unit 7, the frame processing unit 9, and the layer 1 side substrates 21X and 21Y. The device management unit 10 controls each unit in the layer 1 side substrates 21X and 21Y and the layer 2 side substrate 3. In response to the failure detection result by the reception-side failure detection unit 8, the device management unit 10 sends information on the failure detection result to a failure monitoring device (not shown) connected to the outside of the communication device 1 as necessary. Send. The frame processing unit 9 distributes the frames received from the layer 1 side substrates 21X and 21Y to any one of the layer 1 side substrates 21X and 21Y for transmission.

  The layer 1 side boards 21X and 21Y and the layer 2 side board 3 are detachable boards from a mother board (main board) (not shown), and the layer 1 side boards 21X and 21Y and the layer 2 side board 3 are inserted into the motherboard. Thereby connecting each other.

  Here, the OSI (Open System Interconnection) reference model and the IEEE 802.3 sublayer will be described. FIG. 2 is a diagram for explaining the OSI reference model and the IEEE 802.3 sublayer.

  Layer 1 (physical layer) of the OSI reference model includes PHY (Physical Layer Device) composed of “PMD (Physical Medium Dependent)”, “PMA (Physical Medium Atachment)”, and “PCS (Physical Coding Sublayer)”. .

  Layer 2 (data link layer) of the OSI reference model includes “LLC (Logical Link Control)” (LLC sublayer), “MAC (Media Access Control) Control”, and “MAC” (MAC sublayer). “PMA” and “PMD” are physical medium attachments and physical medium dependent sublayers, and “PCS” is a physical encoding sublayer.

  The MII 90 connects “PCS” and “MAC”, and the MII 90 corresponds to the interfaces A to D of the communication apparatus 1. MII90 defines an interface between the MAC layer and the physical layer. Further, “PMD” and “medium” are connected by a predetermined interface.

  Next, as an operation procedure of the communication apparatus 1, a failure detection operation procedure on the LAN line reception side and a failure detection operation procedure on the LAN line transmission side will be described. 3A and 3B are flowcharts illustrating an operation procedure for detecting a failure on the LAN line receiving side of the communication apparatus according to the first embodiment. Here, a case where the layer 1 side board 21X of the communication apparatus 1 receives a frame from a LAN line will be described. The layer 1 side substrate 21X receives the frame from the LAN line by the layer 1 processing unit 41 (step S100). The layer 1 processing unit 41 performs layer 1 processing such as electrical level conversion and code decoding on the received frame, and transmits the frame to the line defect detection unit 51 via the interface A in a frame format based on MII. (Step S110).

  As MII signals, there are RXD <3: 0> (received data), RX_DV (received data valid), RX_ER (received error) on the receiving side (PHY to MAC direction) of interface A and B, for example. These signals are synchronized with RX_CLK (reception clock). The MII signal includes COL (collision detection) and CRS (carrier detection), but can be ignored in full-duplex communication.

  4A to 4D are diagrams illustrating signal timing charts in the interfaces A and B of the communication apparatus according to the first embodiment. In FIGS. 4A to 4D, RXD <3: 0>, RX_DV, and RX_ER signals are shown, and RX_CLK, COL, and CRS signals are omitted.

  RX_ER indicates Low when no abnormality is detected from the frame received by the layer 1 processing unit 41, and High at a point (timing) where the abnormality is detected when abnormality is detected from the frame received by the layer 1 processing unit 41. (On).

  RXD <3: 0> indicates data received by the layer 1 processing unit 41. RXD <3: 0> includes, for example, a frame transmission notification and a preamble for synchronization and an FCS for detecting a transmission error.

  RX_DV indicates High when the data received by the layer 1 processing unit 41 is valid, and indicates Low (interframe gap) when the data received by the layer 1 processing unit 41 is not valid.

  The line failure detection unit 51 starts frame detection using a preamble and FCS check using CRC-32. The line defect detection unit 51 determines whether an abnormality such as a code error has been detected from the frame received via the interface A (step S120).

  For example, when an abnormality such as a code error is not detected from the frame received by the layer 1 processing unit 41 (No in step S120), the line failure detection unit 51 receives RX_ER Low as shown in the signal timing chart of FIG. Is maintained (step S130).

  On the other hand, when an abnormality such as a code error is detected from the frame received by the layer 1 processing unit 41 (step S120, Yes), the line defect detection unit 51 detects the abnormality as shown in the signal timing chart of FIG. RX_ER at the location (timing) is set to High (generation of line failure information) (step S140).

  The line failure detection unit 51 determines whether or not it is detected that the interface A is RX_ER remains Low and that the FCS is abnormal (step S150). As shown in the signal timing chart of FIG. 4C, if the line failure detection unit 51 detects that the interface A is RX_ER remains Low and the FCS is abnormal (step S150, Yes), the line failure is detected. As shown in the signal timing chart of FIG. 4-4, the detection unit 51 sets RX_ER to High at the final frame position in the interface B (step S160).

  The line failure detection unit 51 performs the processing of steps S120 to S160 on the frame based on MII received from the layer 1 processing unit 41, and then transmits the frame based on MII to the layer 2 side substrate 3 via the interface B. (Step S170).

  The layer 2 processing unit 7 of the layer 2 side substrate 3 performs processes such as frame detection, FCS check, length check, preamble removal, etc. on the frame from the layer 2 side substrate 3 transferred via the interface B ( Step S180).

  The layer 2 processing unit 7 notifies (transmits) the FCS check result (received frame abnormality information) by the layer 2 processing unit 7 and RX_ER from the line failure detection unit 51 to the reception side failure detection unit 8 (step S190). Also, the layer 2 processing unit 7 transfers the received frame to the frame processing unit 9 when the received frame is checked normally, and discards the received frame when there is some abnormality in the received frame. Further, the layer 2 processing unit 7 notifies the device management unit 10 of the number of received frames, the number of octets, the number of discarded frames, and the like. The reception-side failure detection unit 8 distinguishes and detects a line failure and a device failure based on the failure detection discrimination condition information 95. Here, the failure detection determination condition information 95 will be described.

  FIG. 5 is a diagram illustrating an example of a configuration of failure detection determination condition information 95 included in the communication apparatus according to Embodiment 1. The failure detection determination condition information 95 is information (information for performing logical determination) for distinguishing and detecting a line failure and a device failure based on RX_ER and the FCS check result in the layer 2 processing unit 7. The failure detection determination condition information 95 includes information on whether RX_ER is High or Low for one clock or more and whether the FCS check result in the layer 2 processing unit 7 is normal or abnormal during the data valid period. Information and information relating to the correspondence between the detection results of the failure (“line failure”, “device failure”, “normal”).

  During the data valid period, RX_ER is High and the FCS check result in the layer 2 processing unit 7 is normal or abnormal is associated with the determination “line failure”. During the data valid period, RX_ER is Low and the FCS check result in the layer 2 processing unit 7 is normal, and the determination “normal” is associated. During the data valid period, RX_ER is Low and the FCS check result in the layer 2 processing unit 7 is abnormal, and the determination “device failure” is associated.

  The reception-side failure detection unit 8 determines whether or not RX_ER is High for one clock or more during the data valid period (Step S200). If RX_ER is High for one clock or more during the data valid period (step S200, Yes), the reception-side failure detection unit 8 determines that “line failure” regardless of the FCS check result in the layer 2 processing unit 7. to decide. In other words, when RX_ER is High for one clock or more, it is determined that “line failure” regardless of whether the FCS check result is normal or abnormal (step S210).

  If RX_ER remains Low during the data valid period (No at Step S200), the reception-side failure detection unit 8 determines whether the FCS check result at the layer 2 processing unit 7 is normal (Step S200). S220).

  If the reception-side failure detection unit 8 determines that the FCS check result in the layer 2 processing unit 7 is normal (step S220, Yes), it is determined as “normal” in which neither a line failure nor a device failure has occurred (step). S230).

  If RX_ER remains low during the data valid period and the FCS check result in the layer 2 processing unit 7 is abnormal (No in step S220), the reception-side failure detection unit 8 determines “device failure”. Is determined (step S240). In other words, if the FCS check result is abnormal, the line failure detection unit 51 determines that the received frame has no FCS abnormality, so that the RX_ER is Low, but the FCS check is performed by the layer 2 processing unit 7. Since this means that an abnormality has been detected, the reception-side failure detection unit 8 determines that some abnormality (in-device failure) has occurred in the connection of the interface B or any FCS check circuit.

  The reception-side failure detection unit 8 notifies the device management unit 10 of the determination results of the determination “line failure”, “normal”, and “device failure” (step S250). The device management unit 10 uses means such as LED (Light Emitting Diode) not shown, generation of an alarm sound by a buzzer, screen display by an external terminal (failure monitoring device or the like (not shown)) via a management interface, and the like. Notify the operator (user of the communication device 1) of an in-device failure or the like.

  FIG. 6 is a flowchart showing an operation procedure for detecting a failure on the LAN line transmission side of the communication apparatus according to the first embodiment. The frame permitted to be transmitted by the frame processing unit 9 is transferred to the layer 2 processing unit 7 after a predetermined output LAN line is selected. Here, a case where the LAN line of the layer 1 side board 21X is selected in the frame processing unit 9 will be described.

  The layer 2 processing unit 7 performs FCS generation, preamble insertion, and the like on the frame from the frame processing unit 9 to generate a frame in a format based on MII. The layer 2 processing unit 7 transfers the frame based on the generated MII to the layer 1 side substrate 21X (transmission side failure detection unit 61) via the interface C (step S300).

  The transmission side failure detection unit 61 of the layer 1 side substrate 21X checks the FCS attached to the frame by the layer 2 processing unit 7. That is, the transmission side failure detection unit 61 determines whether or not the FCS attached to the frame by the layer 2 processing unit 7 is abnormal (step S310).

  If the transmission-side failure detection unit 61 determines that the FCS check result is normal (No at Step S310), the frame is transferred to the layer 1 processing unit 41 via the interface D (Step S320). The layer 1 processing unit 41 performs layer 1 processing such as code encoding and electrical level conversion, and outputs a frame to the LAN line (step S330).

  On the other hand, when the transmission side failure detection unit 61 determines that the FCS check result is abnormal (No in step S310), the connection of the interface C, the FCS generation circuit of the layer 2 processing unit 7, the FCS of the transmission side failure detection unit 61 It can be determined that a failure has occurred in any of the check circuits. Therefore, the transmission side failure detection unit 61 notifies the device management unit 10 of the FCS check result (determination result) determined to be abnormal (step S340).

  The device management unit 10 notifies the operator of a device failure or the like by means such as LED display, generation of an alarm sound by a buzzer, or screen display by an external terminal via a management interface.

  In the first embodiment, the case where the layer 1 side board 21X of the communication apparatus 1 receives a frame from the LAN line has been described. However, the layer 1 side board 21B of the communication apparatus 1 receives the frame from the LAN line. In this case, the failure is detected by the same processing as when the layer 1 side substrate 21X receives the frame.

  In the first embodiment, the communication device 1 includes the layer 1 side substrate 21X and the layer 2 side substrate 21Y. However, the communication device 1 includes one layer 1 side substrate and three or more layers. It is good also as a structure provided with a layer 1 side board | substrate.

  In the first embodiment, in the communication apparatus 1, the layer 1 processing unit 41 and the line failure detection unit 51 are connected via the interface A, and the line failure detection unit 51 and the layer 2 processing unit 7 are connected via the interface B. Although it was set as the structure, the structure of the communication apparatus 1 is not restricted to these structures. That is, in the communication device 1, the arrangement location of the line failure detection unit 51, the transmission side failure detection unit 61, and the interfaces A and B may be changed.

  FIG. 7 is a block diagram showing a configuration of a modified example of the communication device according to the first embodiment. Among the components shown in FIG. 7, the components that achieve the same functions as those of the communication device 1 shown in FIG. The number is attached | subjected and the overlapping description is abbreviate | omitted.

  The interface A has a plurality of connection lines, and connects the layer 1 processing unit 41 and the layer 2 processing unit 7, and the layer 1 processing unit 41 and the line defect detection unit 51. That is, one connection line of the interface A from the layer 1 processing unit 41 is connected to the line defect detection unit 51, and one or more other connection lines are connected to the layer 2 processing unit 7. In the interface A of FIG. 7, a plurality of connection lines from the layer 1 processing unit 41 are illustrated as one connection line.

  Further, the interface B from the line defect detection unit 51 is connected to the layer 2 processing unit 7 together with the interface A. Thereby, RX_ER of the interface A is terminated by the line failure detection unit 51, and RX_ER of the interface B is a signal generated by the line failure detection unit 51.

  The interface C has a plurality of connection lines, and connects the layer 1 processing unit 41 and the layer 2 processing unit 7, and the layer 2 processing unit 7 and the transmission side failure detection unit 61. That is, one connection line of the interface C from the layer 2 processing unit 7 is connected to the transmission side failure detection unit 61, and one or more other connection lines are connected to the layer 1 processing unit 41. As a result, one connection line of the interface C is terminated at the transmission side failure detection unit 61, and the communication apparatus 1 has no interface D. In the interface C of FIG. 7, a plurality of connection lines from the layer 2 processing unit 7 are illustrated as one connection line.

  The communication device 1 shown in FIG. 7 also performs failure detection on the LAN line reception side and failure detection on the LAN line transmission side by the same operation procedure as that of the communication device 1 shown in FIG. Note that, depending on the circuit of the line defect detection unit 51, when the above-described RX_ER High position is input to the layer 2 processing unit 7, there may be a delay of one clock between the interface A and the interface B. It is assumed that the failure detection itself is not affected by shifting the timing of the FCS check result in the side failure detection unit 8.

  As described above, according to the first embodiment, since the layer 1 side boards 21X and 21Y include the line defect detection unit 51, the layer 1 side boards 21X and 21Y can perform frame detection and FCS check. In addition, the layer 2 processing unit 7 performs the FCS check, and also notifies the reception side failure detection unit 8 of the FCS check result in the layer 2 processing unit 7 and the RX_ER from the line failure detection unit 51. It is possible to distinguish and detect line failures and in-device failures on the basis of failure detection determination condition information 95. Therefore, the communication device 1 can detect an in-device failure with a simple configuration and distinguished from a LAN line failure.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, the line failure detection unit 51 and the reception side failure detection unit 8 are connected by a predetermined communication line. FIG. 8 is a block diagram showing the configuration of the communication apparatus according to the second embodiment of the present invention. Among the elements shown in FIG. 8, the elements that achieve the same function as the communication apparatus 1 shown in FIG. 1 or FIG. Are given the same numbers, and redundant explanations are omitted.

  The interface A has a plurality of connection lines, and connects the layer 1 processing unit 41 and the layer 2 processing unit 7, and the layer 1 processing unit 41 and the line defect detection unit 51. That is, one connection line of the interface A from the layer 1 processing unit 41 is connected to the line defect detection unit 51, and one or more other connection lines are connected to the layer 2 processing unit 7. In the interface A of FIG. 8, a plurality of connection lines from the layer 1 processing unit 41 are illustrated as one connection line.

  Further, the line failure detection unit 51 is connected to the reception side failure detection unit 8. In the second embodiment, the line failure notification signal (line failure notification signal line) E from the layer 1 side substrate 21X and the line failure notification signal E from the layer 1 side substrate 21Y are connected to the reception side failure detection unit 8. Yes. In other words, the communication device 1 here does not output the RX_ER signal from the line failure detection unit 51 to the layer 2 processing unit 7, but instead the line failure notification signal E is connected to the reception side failure detection unit 8. Yes. Further, the interface B is lost as the line failure notification signal E is connected to the reception side failure detection unit 8.

  Next, as an operation procedure of the communication apparatus 1, an operation procedure for detecting a failure on the LAN line receiving side will be described. FIGS. 9A and 9B are flowcharts illustrating an operation procedure for detecting a failure on the LAN line receiving side of the communication apparatus according to the second embodiment. Here, a case where the layer 1 side substrate 21X of the communication device 1 receives a frame from a LAN line will be described.

  The layer 1 side substrate 21X receives the frame from the LAN line by the layer 1 processing unit 41 (step S400). The layer 1 processing unit 41 performs layer 1 processing such as electrical level conversion and code decoding on the received frame, and the line failure processing unit 51 and the layer 2 processing in a frame format based on MII via the interface A. The frame is transmitted to the unit 7 (step S410).

  10A to 10C are signal timing charts of the interface A and the line failure notification signal E of the communication apparatus according to the second embodiment. The line failure detection unit 51 starts frame detection using a preamble and FCS check using CRC-32.

  The line failure detection unit 51 determines whether an abnormality such as a code error is detected from a frame received via the interface A (step S420). For example, when an abnormality such as a code error is not detected from the frame received by the layer 1 processing unit 41 (No in step S420), the line failure detection unit 51 notifies the line failure notification as shown in the signal timing chart of FIG. The low level of the signal E is maintained (step S430).

  On the other hand, when an abnormality such as a code error is detected from the frame received by the layer 1 processing unit 41 (Yes in step S420), the line defect detection unit 51 sets RX_ER at a location where the abnormality is detected to be high. Then, as shown in the signal timing chart of FIG. 10-2, the line failure notification signal E is set to High from the place where RX_ER is set to High, and the High is continued until the end of the frame (generation of line failure information) (step S440). .

  The line failure detection unit 51 determines whether or not it has been detected that RX_ER remains Low at the interface A and that the FCS is abnormal (step S450). When the line failure detection unit 51 detects that the interface A is RX_ER remains Low and the FCS is abnormal (step S450, Yes), the line failure detection unit 51 displays the signal timing chart of FIG. 10-3. As shown, the line failure notification signal E is set to High at the final frame position (step S460).

  The line failure detection unit 51 performs the processing of steps S420 to S460 on the frame based on MII received from the layer 1 processing unit 41, and then transmits a line failure notification signal E to the reception side failure detection unit 8 ( Step S470).

  The layer 2 processing unit 7 of the layer 2 side substrate 3 performs processing such as frame detection, FCS check, length check, and preamble removal on the frame from the layer 1 processing unit 41 transferred via the interface A ( Step S480).

  The layer 2 processing unit 7 transmits the FCS check result by the layer 2 processing unit 7 to the reception-side failure detection unit 8 (step S490). Also, the layer 2 processing unit 7 transfers the received frame to the frame processing unit 9 when the received frame is checked normally, and discards the received frame when there is some abnormality in the received frame. Further, the layer 2 processing unit 7 notifies the device management unit 10 of the number of received frames, the number of octets, the number of discarded frames, and the like.

  The reception-side failure detection unit 8 distinguishes and detects a line failure and a device failure based on the failure detection determination condition information 96. Here, the determination condition information 96 for failure detection will be described. FIG. 11 is a diagram illustrating an example of a configuration of failure detection determination condition information 96 included in the communication device according to the second embodiment. The failure detection discrimination condition information 96 is information for distinguishing and detecting a line failure and a device failure based on the line failure notification signal E and the FCS check result in the layer 2 processing unit 7. The failure detection determination condition information 96 includes information on whether the line failure notification signal E is High or Low for one clock or more and the FCS check result in the layer 2 processing unit 7 is normal or abnormal during the data valid period. Information relating to correspondence between failure information and failure detection results (“line failure”, “device failure”, “normal”).

  In the data valid period, the determination “line failure” is associated with the case where the line failure notification signal E is High and the FCS check result in the layer 2 processing unit 7 is normal or abnormal. The determination “normal” is associated with the case where the line failure notification signal E is Low and the FCS check result in the layer 2 processing unit 7 is normal during the data valid period. During the data valid period, the case where the line failure notification signal E is Low and the FCS check result in the layer 2 processing unit 7 is abnormal is associated with the determination “device failure”.

  The reception-side failure detection unit 8 determines whether or not the line failure notification signal E is High for one clock or more during the data valid period (step S500). If the line failure notification signal E is High for one clock or more during the data valid period (step S500, Yes), the reception-side failure detection unit 8 sets the “notification of the FCS check result in the layer 2 processing unit 7”. It is determined that the line is bad. That is, when the line failure notification signal E is High for one clock or more, it is determined as “line failure” regardless of whether the FCS check result is normal or abnormal (step S510).

  When the line failure notification signal E remains Low during the data valid period (No in step S500), the reception-side failure detection unit 8 determines that the reception-side failure detection unit 8 is the FCS check result in the layer 2 processing unit 7. Is determined to be normal (step S520).

  If the reception-side failure detection unit 8 determines that the FCS check result in the layer 2 processing unit 7 is normal (step S520, Yes), it is determined as “normal” in which neither a line failure nor a device failure has occurred (step S520). S530).

  If the line failure notification signal E remains Low during the data valid period and the FCS check result in the layer 2 processing unit 7 is abnormal (No in step S520), the reception-side failure detection unit 8 It is determined that “device failure” (step S540). That is, if the FCS check result is abnormal, the line failure detection unit 51 determines that there is no FCS abnormality in the received frame, so the layer 2 processing unit 7 is in spite of the line failure notification signal E being Low. Means that the FCS abnormality is detected, the receiving side failure detection unit 8 determines that there is some abnormality (in-device failure) in the connection of the interface B or any FCS check circuit.

  The reception-side failure detection unit 8 notifies the device management unit 10 of the determination results of the determinations “line failure”, “normal”, and “device failure” (step S550). The operation procedure for detecting a failure on the LAN line transmission side is the same as that in the first embodiment, and a description thereof will be omitted.

  As described above, according to the second embodiment, since the layer 1 side boards 21X and 21Y include the line defect detection unit 51, the layer 1 side boards 21X and 21Y can perform frame detection and FCS check. In addition, the layer 2 processing unit 7 performs the FCS check, and also notifies the reception side failure detection unit 8 of the FCS check result in the layer 2 processing unit 7 and the RX_ER from the line failure detection unit 51. It is possible to distinguish and detect line failures and in-device failures on the basis of failure detection determination condition information 95. In addition, since the line failure detection unit 51 transmits the line failure notification signal E to the reception-side failure detection unit 8 without going through the layer 2 processing unit 7, the load on the layer 2 processing unit 7 can be reduced. Therefore, the communication device 1 can detect an in-device failure with a simple configuration and distinguished from a LAN line failure.

Embodiment 3 FIG.
Further, in Embodiments 1 and 2 described above, an in-device failure could not be detected when RX_ER became High in interface A. However, when RX_ER is High by performing the following additional processing. Even in such a case, it is possible to detect an in-device failure. That is, for example, when the line defect detection units 51 of the layer 1 side boards 21X and 21Y shown in FIG. 1 are arranged in series with the layer 1 processing unit 41 and the layer 2 processing unit 7, RX_ER of the interface A is When it becomes High, each line defect detection unit 51 causes the FCS to be erroneously transferred to the interface B.

  When RX_ER is High in the failure detection determination condition information 95 of FIG. 5 and the FCS check result in the layer 2 processing unit 7 is “normal”, the FCS check result by the line failure detection unit 51 and the layer 2 The FCS check results by the processing unit 7 are inconsistent, and it is possible for the reception side failure detection unit 8 to detect that an in-device failure has occurred.

  As described above, according to the third embodiment, even when RX_ER becomes High in the interface A, the communication device 1 can detect a failure in the device with a simple configuration and distinguished from a LAN line failure. It becomes possible.

  The embodiment described above is only an example, and the arrangement position of the line defect detection unit 51 and the arrangement position of the transmission side fault detection unit 61 can be either serial arrangement or parallel arrangement. The arrangement of the transmission-side failure detection unit 61 can detect an in-device failure by any combination.

  In the embodiment described above, the frames A to D transmit and receive frames in a frame format based on MII. However, if the interface uses FCS, GMII (Gigabit MII), Reduced MII, and wireless LAN The present invention is applicable to various interfaces such as IEEE 802.11 PHY-MAC interface which is a standard.

  As described above, the communication failure detection apparatus according to the present invention is suitable for detecting an in-device failure.

It is a block diagram which shows the structure of Embodiment 1 of the communication apparatus which concerns on this invention. FIG. 6 is a contrast diagram for explaining an OSI reference model and an IEEE 802.3 sublayer. 6 is a flowchart (1) illustrating an operation procedure for detecting a failure on the LAN line receiving side of the communication apparatus according to the first embodiment. 6 is a flowchart (2) illustrating an operation procedure for detecting a failure on the LAN line receiving side of the communication apparatus according to the first embodiment. FIG. 3A is a diagram (1) illustrating a signal timing chart in interfaces A and B of the communication device according to the first embodiment. FIG. 6B is a diagram (2) illustrating a signal timing chart in the interfaces A and B of the communication device according to the first embodiment. FIG. 6C is a diagram (3) illustrating a signal timing chart in the interfaces A and B of the communication device according to the first embodiment. 6 is a diagram (4) illustrating a signal timing chart in the interfaces A and B of the communication apparatus according to Embodiment 1. FIG. 4 is a diagram illustrating an example of a configuration of failure detection determination condition information included in the communication device according to Embodiment 1. FIG. 4 is a flowchart showing an operation procedure for detecting a failure on the LAN line transmission side of the communication apparatus according to the first embodiment. 6 is a block diagram showing a configuration of a modified example of the communication apparatus according to Embodiment 1. FIG. It is a block diagram which shows the structure of Embodiment 2 of the communication apparatus which concerns on this invention. 6 is a flowchart (1) illustrating an operation procedure for detecting a failure on the LAN line receiving side of the communication apparatus according to the second embodiment. 12 is a flowchart (2) illustrating an operation procedure for detecting a failure on the LAN line receiving side of the communication apparatus according to the second embodiment. FIG. 10 is a signal timing chart (1) of an interface A and a line failure notification signal E of the communication apparatus according to the second embodiment. 6 is a signal timing chart (2) of the interface A and the line failure notification signal E of the communication apparatus according to Embodiment 2. FIG. FIG. 11 is a signal timing chart (3) of the interface A and the line failure notification signal E of the communication apparatus according to the second embodiment. 6 is a diagram illustrating an example of a configuration of failure detection determination condition information included in a communication device according to Embodiment 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Communication apparatus 3 Layer 2 side board | substrate 7 Layer 2 process part 8 Reception side fault detection part 9 Frame process part 10 Apparatus management part 21X, 21Y Layer 1 side board 41 Layer 1 process part 51 Line defect detection part 61 Transmission side fault detection part 90 MII
95, 96 Discrimination condition information A to D Interface E Line failure notification signal

Claims (8)

In a communication failure detection apparatus that detects a communication failure connected to a LAN line,
Layer 1 processing means for performing layer 1 processing depending on a medium for a received frame received from the LAN line;
Line failure detection means for detecting a LAN line abnormality in the reception direction from the LAN line based on the received frame and generating line defect information relating to the LAN line abnormality;
The received frame from the line failure detection means performs processing subsequent to layer 2 independent of the medium, detects an abnormality in the received frame based on a frame check sequence of the received frame, and detects an abnormality in the received frame. Layer 2 processing means for generating received frame abnormality information relating to:
Based on the line failure information generated by the line failure detection means and the reception frame abnormality information generated by the layer 2 processing means, the LAN line is normal in the line failure information and the reception frame abnormality information A reception-side failure detection means for determining that a failure has occurred in the device and detecting a failure in the device when the received frame is abnormal in
With
The line defect detection means, when detecting the LAN line abnormality, generates the line defect information and transmits the received frame in which the frame check sequence is mistaken to the layer 2 processing means,
The failure detection means on the receiving side determines that the LAN line is abnormal when the line failure information is received via the layer 2 processing means, the LAN line is abnormal, and the received frame is detected in the reception frame abnormality information. A communication failure detection device , which determines that an in-device failure has occurred when it is normal and detects the in-device failure. The line failure detection means and the layer 2 processing means are connected by a predetermined interface,
The line failure detection means generates the line failure information by changing predetermined data in the received frame and transmits the generated line failure information to the layer 2 processing means by a signal based on the interface,
The communication failure detection apparatus according to claim 1, wherein the layer 2 processing means transfers the line failure information to the reception side failure detection means. 3. The communication failure detection apparatus according to claim 2 , wherein the predetermined data in the reception frame changed by the line failure detection means is a data error signal indicating an error of the reception data in the reception frame. The line defect detection means turns on the data error signal and turns the received frame on when the received data signal abnormality in the received frame or the received frame error based on the frame check sequence of the received frame is detected. To the layer 2 processing means,
The communication failure according to claim 3, wherein the reception-side failure detection means determines that the LAN line is abnormal when the data error signal received through the layer 2 processing means is on. Detection device. The line defect detection means and the reception side failure detection means are connected by a predetermined communication line,
2. The communication failure detection apparatus according to claim 1, wherein the line failure information is transmitted from the line failure detection unit to the layer 2 processing unit via the communication line. The line defect detecting means turns on the line defect information and detects the line defect information when detecting an abnormality of a signal of received data in the received frame or an abnormality of the received frame based on a frame check sequence of the received frame. Send to the receiving side failure detection means,
The receiving side fault detection means, the communication fault detection apparatus according to claim 1 or 5 wherein the line defect information is the LAN line in the case of ON, characterized in that determined to be abnormal. A transmission-side failure detection unit that detects an abnormality of the transmission frame as a failure in the apparatus based on a frame check sequence of the transmission frame with respect to a transmission frame transmitted by the layer 2 processing unit to the LAN line; The communication failure detection apparatus according to any one of claims 1 to 6 , wherein It further includes one to a plurality of first and second substrates connected to each other by being attached on the main substrate,
Each of the first substrates includes at least one of the layer 1 processing means and the line failure detection means;
Communication failure detection apparatus according to any one of claims 1-7, wherein the second substrate is characterized by comprising the layer 2 processing section.

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