JP4570421B2 - Network redundancy system - Google Patents

Description

  The present invention relates to a transmission terminal, a reception terminal, and a network redundant system.

  In recent years, communication services using Ethernet (registered trademark) are rapidly spreading. And as service scale increases, communication services are required to have high operability and reliability. As a countermeasure, there is a redundant configuration of the network.

  In a network network redundancy configuration, when communication is performed via a single route in communication between users, communication failure occurs due to a route failure, and communication is disabled until the failure is recovered. It is a means to avoid falling.

  Specifically, in a network, communication paths between apparatuses accommodating users are constructed by a plurality of paths. Then, an arbitrary one route is selected and used among the plurality of routes. Here, when a failure occurs in the use route, the communication route is switched to another route of a plurality of communication routes. This makes it possible to shorten the communication interruption time.

  Here, network redundancy between two sites using a spanning tree protocol (hereinafter simply referred to as STP) as a conventional technology example will be described with reference to FIG. FIG. 14 is a schematic diagram of a network redundancy system using STP. STP is to uniquely determine a route from a network configuration in which a loop is generated, and blocks data other than the route to block data from passing. Is a protocol for building a tree structure without loops.

  Specifically, as shown in FIG. 14 (a), a network composed of five switches 1, 2, 3, 4, and 5 is assumed. When performing communication from the user A to the user B and the user C, blocking between the switch 2 and the switch 5 and between the switch 3 and the switch 4 makes a logical communication path as shown in FIG. As shown in (a), the following two paths are constructed.

A → Switch 1 → Switch 2 → Switch 4 → B
A → Switch 1 → Switch 3 → Switch 5 → C
In a switch in which STP operates, a control frame called BPDU (Bridge Protocol Data Unit) is used to exchange information between the switches and to construct a tree structure.

  BPDUs are exchanged at regular time intervals to monitor the network. When a change such as a line failure or device failure or addition occurs in the network, the route is automatically reconfigured again using a unique protocol. An example of operation during reconfiguration is shown below.

  As shown in FIG. 14B, when a failure occurs in the circuit between the switch 2 and the switch 4, the circuit failure is detected by the switch 2 and the switch 4, and the circuit where the failure has occurred is blocked. After recalculating a new route by exchanging BPDUs, the blocking between the switch 3 and the switch 4 is released, and communication is restored.

With the above operation, as shown in FIG. 14C, the following route is reconstructed as a new route.
A → Switch 3 → Switch 4 → B
By configuring network redundancy using STP, there is no logical loop, and it is possible to continue communication by constructing a new route even if a route change such as a line or device failure occurs. It is.
JP 2000-151634 A JP 2003-218911 A

  Although the conventional network redundancy system has succeeded in improving the operability and reliability of the network by configuring the network redundancy, it is caused by the signal interruption due to the network switching time, the bug of the protocol itself, and the equipment failure. Higher operability and reliability, such as communication problems such as loop accidents that occur relatively easily and all the devices that make up the network must have specific functions Couldn't build a network with

  For example, in STP, it takes about 15 minutes from the occurrence of a failure in a line within a communication network to the reconstruction of a new route through the detection of a failure (using high-speed STP). Will spend about 1 minute).

  That is, when a certain line breaks down, the entire network completely falls into a communication disconnection state for about one to a dozen minutes. When a failure occurs, if a failure in blocking occurs due to a failure of a representative switch (route switch) that performs path configuration, reconfiguration, or a switch at both ends of a blocking line, a loop state may occur. In addition, it is necessary that all devices in the network have the STP function. Even if other devices are installed in the network and cause a failure, failure information cannot be detected.

  Also, in the conventional network redundancy system, frames for checking network communication disconnection are transmitted at regular intervals regardless of the network traffic. Therefore, when checking network communication disconnection, network traffic is adversely affected. There was to give. Here, a frame for checking a network communication interruption is called a CC (Continuity Check) frame, and a system for detecting a network communication interruption by transmitting this CC frame is called a CC system.

  Here, the conventional CC system will be described with reference to FIG. FIG. 15 is a schematic diagram of the operation of the conventional CC method. In communication between the terminal of user A and the terminal of user B, transmitting end apparatus A multicasts CC frames to receiving end apparatus B at regular time intervals. The CC frame will be described later.

  The receiving end device B confirms the normality of the path by normal reception of frames such as user frames and CC frames (S1501). Hereinafter, a case where a frame other than the CC frame is not transmitted will be described as an example. When a failure occurs in the path between the transmitting end device A and the receiving end device B (S1502), the receiving end device B detects the non-arrival of the CC frame (S1503). The receiving end device B measures the non-arrival time of the CC frame, and regards the path as a failure when the non-delivery time exceeds a certain time (S1504).

In order to notify the transmission end device A of the line disconnection, the receiving end device B that has regarded the path as a failure transmits the line disconnection information on the CC frame (S1505). This CC frame is transmitted to the transmitting end device using a backup path that does not fail, which will be described later. When the transmission end device A receives the CC frame notifying the line disconnection, the transmitting end device A regards the corresponding route as a line disconnection (S1506).
).

  Even after the failure occurs, the transmitting end device A continues to transmit the CC frame, and when the failure is recovered (S1507), the receiving end device B again receives the CC frame normally (S1508). The receiving end device B detects the failure recovery by normally receiving the CC frame even once after detecting the failure of the path (S1509).

  With this operation, the conventional system detects a failure at any position on the active system path and the standby system path, and even if both systems recognize that there is a failure, other than the path of the system where the failure occurred Switches connected through a path and capable of normal communication can be continued without being affected by the failure.

  However, in the conventional CC system as described above, in an IP network, the amount of traffic flowing through the line is variable, and sometimes the traffic is stopped or the entire line bandwidth is used by the user frame. Therefore, if the user frame is using all of the circuit bandwidth, if the CC frame is continuously output at a constant interval, the user frame bandwidth may be eroded, and vice versa. May be discarded by the time it reaches the receiving end device. For this reason, it may be difficult to accurately detect the disconnection of the network.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a transmission terminal, a reception terminal, and a network network redundancy system that can provide high operability and reliability in a network.

In order to solve the above problems, the transmission terminal of the present invention is:
A sending terminal connected to multiple routes,
A measuring means for measuring a time during which data is not transmitted to the route;
A determination data transmission unit configured to transmit data for determining communication disconnection to the plurality of paths when the time measured by the measurement unit exceeds a predetermined time;

The receiving terminal of the present invention is
A receiving terminal that accommodates user terminals connected to a plurality of routes,
Measuring means for measuring the non-delivery time of data from the route;
And switching means for switching a path using the received data from the plurality of paths when the time measured by the measuring means exceeds a predetermined time.

Moreover, the network redundant system of the present invention is
A transmission terminal that accommodates a user terminal that transmits data to both the first route and the second route, and is a time during which data is not transmitted to the first route and the second route. A transmitting terminal for measuring and transmitting data for determining communication interruption to the first route and the second route when the measured time exceeds a predetermined time;
Connected by the transmitting terminal, the first route and the second route;
Whether the data non-delivery time is measured, and when the measured data non-delivery time exceeds a predetermined time, whether data received from the first route or data received from the second route is used And a receiving terminal that accommodates the user terminal.

Moreover, the network redundant system of the present invention is
In the receiving terminal, when the switching occurs,
The receiving terminal transmits data indicating that the switching has occurred to the network in order to cause the switching to be performed in another receiving terminal configuring the network.

Moreover, the network redundant system of the present invention is
The receiving terminal is
The data from the route not using the received data is discarded.

  The present invention measures the time during which the transmitting terminal is not transmitting data to a route, and transmits data for determining communication interruption to a plurality of routes when the measured time exceeds a predetermined time. As a result, data for determining communication interruption according to the traffic state of the network is transmitted. That is, according to the present invention, data for determining communication disconnection is transmitted in the idle time of data transmission, and therefore, adverse effects on network traffic can be reduced even when communication disconnection is determined.

  Further, the present invention is a receiving terminal that accommodates a user terminal, measures a time when data is not received from a route, and when a measured time exceeds a predetermined time, a plurality of times are received. By switching the path for receiving the data to be used from among the paths, it is not necessary for all the devices constituting the network to have a network switching function for the path switching.

  In addition, the present invention provides a transmission terminal accommodating a user terminal, in which the network redundant system transmits data to both the first route and the second route, and includes the first route and the second route. A transmission terminal that measures a time during which data is not transmitted on a route, and transmits data for determining communication disconnection to the first route and the second route when the measured time exceeds a predetermined time And the non-delivery time of data connected by the transmitting terminal, the first route, and the second route, and when the measured non-delivery time exceeds a predetermined time, the first route By providing a receiving terminal that accommodates a user terminal that switches between using received data or using data received from the second route, data for determining communication interruption at a time when data is not transmitted By sending Since data for determining communication disconnection can be transmitted according to the state of network traffic, adverse effects on network traffic can be reduced even when determining communication disconnection, and Therefore, it is not necessary for all devices constituting the network to have a network switching function.

  In addition, the present invention indicates that when a switching occurs in the receiving terminal in the network redundant system, the switching occurs in order for the receiving terminal to perform switching in other receiving terminals constituting the network. By transmitting data to the network, the network can be switched in a short time.

  Further, according to the present invention, the network redundant system can avoid the loop of the data path in the network by discarding the data from the path not using the received data at the receiving terminal.

The best mode for carrying out the present invention will be described below with reference to the drawings. The configuration of the following embodiment is an exemplification, and the present invention is not limited to the configuration of the embodiment. The outline of one embodiment of the network redundant system of the present invention will be described below. The following description also serves as a description of an embodiment of the transmission terminal and the reception terminal of the present invention. One embodiment of the network network redundancy system of the present invention is a network network terminal (user) having a function of transmitting and receiving CC (Continuity Check) frames by the CC method and a line redundancy function by 1 + 1 protection in an IP network. The network redundancy is configured by installing it in the equipment that accommodates the terminal. When communication interruption occurs in the network, the arrival frame interval is checked and switching is performed for each network. Avoid communication interruptions.

(Description of CC system of this embodiment)
First, the CC system applied to one embodiment of the network network redundancy system of the present invention will be described. The apparatus for transmitting a CC frame in the present embodiment does not always output the CC frame at a constant time interval, but outputs it when the user traffic frame transmission stops for a certain period of time. The CC frame transmission according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic diagram of CC frame transmission operation in an embodiment of the network redundant system of the present invention.

  The transmitting end device A measures the time until the next frame is output after outputting the user frame (S101), and the timer is canceled at the time of transmitting the next frame and starts measuring again. (S102).

  When the time set in the apparatus times out while the frame from the user stops and no frame flows, the transmitting end apparatus A transmits a CC frame (S103). Further, by transmitting the user frame before the timeout, the transmitting end device A stops transmitting the CC frame (S104).

  That is, the transmitting end device A does not transmit the CC frame when the user traffic continues to flow, and transmits the CC frame at a constant time interval only when the user traffic is stopped. Then, when the receiving end device B cannot detect both the user traffic frame and the CC frame within a predetermined time, the receiving side detects a communication disconnection. As a result, the transmitting end device A and the receiving end device B can exchange CC frames without affecting the rate of user traffic.

(Explanation of 1 + 1 protection)
Next, 1 + 1 protection in this embodiment will be described. In this embodiment, 1 + 1 protection means that any two physical lines are selected as a route, and one of them is an active system (Work) and the other is a protection system (Protection), and a failure has occurred in the active system route. This is a function for realizing path redundancy by avoiding communication interruption by switching to a backup path.

  1 + 1 protection includes the Distribution function (a function that transmits data to both the active system and the standby system at the transmitting end apparatus) and the Selector function (the receiving end apparatus selects data from the active system and discards the data from the standby system) Function).

  A switching method by 1 + 1 protection in this embodiment will be described with reference to FIG. FIG. 2 is a schematic diagram of a switching method by 1 + 1 protection in an embodiment of the network redundant system of the present invention.

  The frame 201 addressed to the line for which 1 + 1 protection is set in the frame sent to the transmitting end device 200 is copied to both the active system and the standby system by the Distribute function unit 202 in the apparatus, and the path of the active system Are transmitted from the transmission end device 200 to both the backup path and the backup path.

The receiving end device 206 receives frames from both the active route and the standby route. Then, the frame analysis unit 203 of the receiving end device 206 analyzes the data in the frame. The frame analysis operation in the frame analysis unit 203 will be described later with reference to FIG. The frame analysis unit 203 can check the normality of the active route and the standby route by analyzing the data in the frame.

  After the analysis is completed, the selector function unit 204 in the receiving end device 206 discards the frame received from the backup route and passes only the frame received from the active route. As a result, only the frame 205 from the active route is selected and transmitted to the destination line. Note that the 1 + 1 protection 207 shown in FIG. 2 is a network composed of lines, relay devices, and the like.

  The receiving end device 206 receives the same frame on the active route and the standby route, but the selector function unit 204 does not cause frame overlap or loop. When the line of the active system path fails, switching between the active system path and the standby system path is performed when the apparatus detects the failure, but the actual switching operation is performed by the selector function unit 204 of the receiving end apparatus. Only switches the path for discarding the frame, and does not depend on the switching state of the transmitting end device 200.

  Even when this operation is performed, the 1 + 1 protection is not necessarily set for the opposite device on the network of the device for which the 1 + 1 protection is set. Even if the active system and the standby system are connected to different devices, the function of transmitting the same frame to the lines of both systems and discarding the frame from the standby system remains the same. Further, in the 1 + 1 protection, after a failure is detected and switched once in the active system, even if the original operational system recovers, the switchover is not performed.

  As described above, the present embodiment combines the CC method and the 1 + 1 protection function, and installs the transmission end device or the reception end device having both functions in the device of the user accommodation station that accommodates the user terminal of the communication network, By configuring the route and the backup route as separate routes, the operation route and the backup route are constructed between the user accommodation stations, and the respective route information is analyzed while the communication network Build redundancy.

(Example of network redundancy system construction)
Next, a construction example of an embodiment of the network redundant system of the present invention will be described with reference to FIG. FIG. 3 is a schematic diagram of a construction example of an embodiment of the network redundant system according to the present invention.

  FIG. 3 shows a network for performing communication between the terminal of user A and the terminal of user B, the terminal of user C, and the terminal of user D. The solid line is the active route, and the dotted line is the standby route. To do. By the path 301, the terminal of the user A is accommodated in the transmission end device A installed in the accommodation station. The transmission end device A is set to 1 + 1 protection, the route 302 is the active route, and the route 303 is the standby route.

  The path is connected to the two switches W1 and P1 as the center station, the switch connected to the operation path 302 is W1, and the switch connected to the standby path 303 is P1. To do. The switch W1 is a network redundant operation system, and all the switches connected thereafter are positioned as the operation system.

  The switch P1 serves as a backup system path and constructs a path different from the active system. When the center station is further connected to the central station, two switches that are the active system and the standby system are installed in the central station, and switches that match the respective systems are connected to each other.

  In FIG. 3, the active system connects the switch W1 and the switch W2 through a path 304a, and connects the switch W1 and the switch W3 through a path 305a. Further, the standby system connects the switch P1 and the switch P2 through the path 304b, and connects the switch P1 and the switch P3 through the path 305b.

  The receiving station that is set to 1 + 1 protection is installed in the accommodating station that accommodates the user terminal and is connected to the central station, and as shown in FIG. 2 described above, the active switch of the central station and the 1 + 1 protection are installed. Are connected to the standby system switch of the aggregation station and the standby system path of the 1 + 1 protection.

  The path 306a connects the switch W2 and the active system of the receiving end apparatus B, the path 306b connects the switch P2 and the standby system of the receiving end apparatus B, and the path 307a connects the switch W3 and the receiving end apparatus C. The path 307b connects the switch P3 and the standby system of the receiving end device C, the path 308a connects the switch W3 and the operating system of the receiving end device D, and the path 308b P3 and the standby system of the receiving end device D are connected.

  FIG. 4 summarizes the above configuration for each user. FIG. 4 is a schematic diagram summarizing the construction example of one embodiment of the network redundant system shown in FIG. 3 for each user. 4A shows a route from the user A terminal to the user B terminal, and FIG. 4B shows a route from the user A terminal to the user C terminal and the user D terminal. .

  As shown in FIG. 4, in this embodiment, 1 + 1 protection is set at the transmitting end device and the receiving end device of the accommodating station, and two switches that are the active system and the standby system are installed at the center station and the aggregation station. Thus, the route can be divided into the active system and the standby system, and it can be seen that network redundancy is configured.

(Internal configuration of transmitting end device and receiving end device)
Next, the internal configuration of the transmitting end device and the receiving end device used in one embodiment of the network network redundancy system of the present invention will be described with reference to FIG. FIG. 5 is a schematic diagram of the internal configuration of the transmitting end device and the receiving end device used in one embodiment of the network redundant system of the present invention.

  FIG. 5 shows a flow of a user frame and a flow of transmission / reception of a CC frame when a frame is transmitted from a user A terminal to a user B terminal. In the example shown in FIG. 5, there is no switch or relay device between the transmission end device 500 and the reception end device 512, but in this embodiment, the transmission end device 500 and the reception end device 512 are not connected. There may be a switch or a relay device between them. In the example shown in FIG. 5, the transmitting end device 500 and the receiving end device 512 are connected by an active route 513 and a standby route 514. The transmitting end device 500 receives the user frame from the user A terminal (S501). Then, the transmission check unit 501 transmits the received user frame to the opposite device.

  The transmission unit 515 of the transmission end device 500 includes a transmission check unit 501, a transmission timer 502, a CC frame transmission unit 503, and a distribution function unit 504. The transmission timer 502 measures the frame transmission interval (S502). The transmission timer 502 cancels the timer at the timing when the transmission check unit 501 transmits a frame (timer value = 0), and continues to add the timer value until the next frame is transmitted after the frame is transmitted.

When a certain time (time can be set) elapses after transmitting the user frame, the transmission timer 502 times out. The transmission timer 502 notifies the CC frame transmission unit 503 of a timeout (S503). The CC frame transmission unit 503 receives the timeout notification and transmits a CC frame (S504).

  The CC frame is transmitted from the transmission check unit 501 similarly to the user frame (S505). In addition, when transmitting a CC frame, the transmission timer 502 executes cancellation in the same manner as a user frame. With this operation, even if the transmission of the user frame is delayed, it is possible to continue transmitting the CC frame every certain time.

  When a frame is transmitted from the transmission end device 500, the frame is copied by the Describe function unit 504, and the same frame is transmitted to both of the operation route and the protection route including the 1 + 1 protection. The

  The receiving end device 512 receives frames from both the active route and the standby route. The receiving end device 512 confirms the reception of the frame from the active system path in the active system reception check unit 505 and confirms the reception of the frame from the standby system path in the standby system reception check unit 506.

  The reception end device 512 includes a reception unit 516 and a transmission unit 517. The receiving unit 516 includes an active system reception check unit 505, a standby system reception check unit 506, an active system reception timer 507, a standby system reception timer 508, a frame analysis unit 509, and a selector function unit 510. The transmission unit 517 includes a CC frame transmission unit 511.

  For the handling system reception check unit 505 and the standby system reception check unit 506, similarly to the transmission check unit 501, the operation system reception timer 507 and the standby system reception timer 508 respectively receive frame reception intervals (frame non-arrival time). Measurement (S506, S507) is performed.

  The active reception timer 507 and the standby reception timer 608 cancel the timer at the timing when the active reception check unit 505 and the standby reception check unit 506 receive the frame (timer value = 0). The timer value is continuously added until the next frame is received.

  When the received frame passes through the active system reception check unit 505 and the standby system reception check unit 506, the received frame is sent to the frame analysis unit 509. The frame analysis unit 509 performs identification of the user frame and the CC frame and bit monitoring in the CC frame, and determines whether the received frame is a CC frame for notifying switching.

  For the received frame that has passed through the frame analysis unit 509, the selector function unit 510 discards the frame from the standby system and transmits the frame from the active system to the user B terminal (S508). The above is the flow of received frames when switching at the receiving end device 512 and CC frame transmission are not involved. Next, in this embodiment, the operation when switching the path and transmitting the CC frame will be described.

  When a fixed time (time can be set) elapses after the user frame is received in the active reception check unit 505 and the standby reception check unit 506, the active reception timer 507 times out and a wait of about 10 ms (standby system) (Time-out waiting wait process), the active reception timer 507 confirms the timer value of the standby reception timer 508 (S509).

Here, if the timer value of the standby reception timer 508 also times out in the same way as the timer value of the active reception timer 507, the receiving end device 512 switches the path as a communication interruption state rather than a path failure. First, the frame is transmitted to the frame analysis unit 509.

  However, if the timer value of the standby reception timer 508 and the timer value of the active reception timer 507 are different, the receiving end device 512 regards that a path failure has occurred, and the active reception timer 507 determines that the selector function unit A route switching request is issued to 510 (S510).

  Upon receiving this notification, the selector function unit 510 of the receiving end device 512 switches the path from the active system path to the standby system path, and the active system reception timer 507 transfers the path to the standby system to the CC frame transmission unit 511. The switching is notified (S511). The CC frame transmission unit 511 that has received the notification transmits the CC frame in which the switching response bit is described in the frame by the same operation as the CC frame transmission unit 503 of the transmission end device 500 (S512).

  In addition, after the frame passes through the active reception check unit 505 and the standby reception check unit 506, the frame analysis unit 509 analyzes the frame. If the switching of the opposite device is detected as a result of the bit monitoring of the CC frame by the frame analysis unit 509, the frame analysis unit 509 issues a path switching request to the Selector function unit 510 along the bit monitoring result (S513). The CC frame transmission unit 511 is notified of CC frame transmission (S514).

(Operation when a failure occurs in the network path)
Next, in the embodiment of the network redundant system of the present invention, a case where a failure occurs in the constructed network path will be described with reference to FIG. FIG. 6 is a schematic diagram when a failure occurs in the constructed network path in the embodiment of the network redundancy system of the present invention.

  In FIG. 6, in order to confirm the normality of the path at the transmitting end device and the receiving end device in the accommodating station in the network, the transmitting end device of the accommodating station transmits the CC frame to multicast while the user traffic is stopped. Send at regular intervals. However, when there are a plurality of connection target devices and communication is performed only with a single device among them, CC frames are not transmitted in order not to affect the band of user traffic.

  The receiving end device (for example, the receiving end device B in which the terminal of the user B is accommodated) recognizes the normality of the route by receiving the frame within the frame non-arrival timer regardless of the user frame or the CC frame. Here, the frame received from the standby system in the 1 + 1 protection is discarded in the receiving end device by the Selector function unit after the frame data is analyzed. By this operation, it is possible to confirm the normality of the path even in the backup path for discarding frames. The operation of the configuration shown in FIG. 6 will be described in detail later.

(CC frame format)
Next, the frame format of the CC frame used in one embodiment of the network redundant system of the present invention will be described with reference to FIG. FIG. 7 is a schematic diagram of a frame format of a CC frame used in an embodiment of the network redundancy system of the present invention.

  The CC frame shown in FIG. 7 conforms to IEEE 802.1Q and follows the frame format of the Ether frame. By uniquely setting Ethertype as the identifier, the CC frame is recognized at the timing of frame analysis at the receiving end device.

  In the CC frame, there are a Status field and a Data field as data fields unique to the CC frame. FIG. 8 shows the bit definition of the Status field and the meaning of the Status field. FIG. 8 is a table showing the definition of the Status field of the CC frame shown in FIG. 8A shows the status field definition for each bit, and FIG. 8B shows the bit definition. The Data field contains a repetition of 0x00. As shown in FIG. 8A, the Status field contains a bit indicating the status of the active system in the 6th bit, a bit indicating the status of the switching notification in the 7th bit, and a switch in the 8th bit. Contains a bit indicating the response.

  The frame analysis unit 203 shown in FIG. 2 and the frame analysis unit 509 shown in FIG. 5 analyze the Status field definition shown in FIG. 8A and acquire information stored in the CC frame. For example, as shown in FIG. 8B, the frame analysis unit 203 is in a normal state on the active system 0 side if (active system, switch notification, switch response) is (0, 0, 0). If (active, switching notification, switching response) is (0, 1, 0), it is analyzed that switching occurs on the active system 0 side, and (active, switching notification, switching response) is If (0, 0, 1), the active system 0 side analyzes the switching response, and if (active system, switching notification, switching response) is (0, 1, 1), the active system 0 side. Analyze switching occurrence and response status. Here, the active system 0 side and the active system 1 side shown in the “state” of FIG. 8B indicate one and the other of the two paths, respectively. For the sake of convenience, one route is designated as the active system 0 side, and the other route is designated as the active system 1 side.

  Then, as shown in FIG. 8B, the frame analysis unit 203 shown in FIG. 2 and the frame analysis unit 509 shown in FIG. 0 (0, 0), the normal state is analyzed on the active system 1 side, and if (active system, switching notification, switching response) is (1, 1, 0), switching occurs on the active system 1 side. If the analysis is (active system, switching notification, switching response) is (1, 0, 1), the operating system 1 analyzes the switching response, and (active system, switching notification, switching response) is ( 1, 1, 1), the operation system 1 side analyzes the occurrence of switching and the response state.

(System switching procedure)
Next, in the embodiment of the network network redundancy system of the present invention, a system switching procedure due to frame non-arrival at the receiving end device will be described with reference to FIG. FIG. 9 is a flowchart showing a system switching procedure due to non-arrival of a frame in the receiving end device in an embodiment of the network redundant system of the present invention.

  In the present embodiment, the receiving end device performs path switching when a frame non-delivery time is timed out. There are three reasons for the time-out, and the system switching method differs depending on the case.

  Causes of timeout include (1) one-system communication disconnection due to path failure, (2) both-system communication disconnection due to path failure, and (3) a frame sent to its own device because the opposite device is communicating with another device. If the active side is disconnected in the case of (1), it is necessary to switch the route. In (2) and (3), it is necessary to switch the route. Absent.

Hereinafter, the switching procedure of this embodiment will be described along the flow of FIG. When the transmission from the opposite device stops, the receiving end device starts measuring the time with the frame non-arrival timer in both the active system and the standby system (S901, S902, S912). When a frame from the opposite device arrives during measurement, the next frame is again waited (Yes in S903, Yes in S913).

When the next frame does not arrive (No in S903, No in S913) and the time-out occurs (S904, S914), the receiving end device takes a protection time of 10 msec in the active system (
S905). As a result, even if there is a difference in the route difference or the number of routed devices between the active system and the standby system when the transmission from the opposite device is stopped at the same time, the difference can be absorbed.

  The receiving end device confirms the timer value of the standby system after the protection time of 10 msec (S906, S915, S916, S907), and if the standby system also times out (S908, Yes), (2) both system failures, Alternatively, (3) it is determined that no traffic is flowing from the opposite device, and the path is not switched.

  If the timer value of the standby system has not timed out, the receiving end device determines that a path failure has occurred in one of the networks, and performs system switching (S909, S910, S917, S911). First, the active system becomes the new standby system, and then the standby system becomes the new active system, so that no frame loop occurs.

(If a failure occurs in the operational system in the network)
Next, a case where a failure occurs in the operational system in the network will be described. When a failure occurs in the operational system in the network, the path is disconnected, and the frame does not reach the receiving end device of the accommodation station.

  Using the frame non-arrival time timeout as a trigger, the receiving end device of the accommodation station detects an abnormality in the active system path and switches to the standby system path. The receiving end device of the accommodating station that has performed switching to the backup path sets the switch notification bit for the active system in the Status field of the CC frame, and multicasts the switch notification to other devices.

  The receiving end device of the other accommodating station that has received the switching notification CC frame immediately switches the selected route to the backup route, and returns the switching response bit in the frame. This operation makes it possible to switch from the active system to the standby system in the entire network.

  The transmitting end device of the accommodation station transmits a normal CC frame again after detecting a path abnormality by a CC frame with a control bit. The receiving end device of the accommodation station detects the failure recovery of the path when one CC frame is received.

(Frame transmission operation)
Next, in one embodiment of the network redundant system of the present invention, the same frame is applied to both the active route and the standby route by the 1 + 1 protection so that the transmission end device does not depend on the state of the opposite device. The operation when transmitting is described.

  The receiving end device does not depend on the status of the opposite device, receives frames from both the active route and the standby route, performs data analysis, and then receives frames from the standby route in the device. Is discarded, and only frames from the active route are passed.

  Therefore, without knowing the configuration of the opposite device or the entire network, the transmitting end device or receiving end device of the accommodation station and the transmitting end device or receiving end device of another accommodation station perform transmission and reception of frames. Regardless of the type of switch other than the transmitting end device or receiving end device of the accommodating station, this embodiment functions without any problem. In this embodiment, the redundancy of two types of networks is taken, and 1 + 1 protection is executed in the apparatus, so that a frame loop does not occur in principle.

(Switching completion time)
Next, the switching completion time in one embodiment of the network redundant system of the present invention will be described. In the switching method using 1 + 1 protection according to the present embodiment, it is possible to implement the switching from the detection of a failure to the completion of the switching in about 50 ms.

  That is, the time required from when a failure occurs in the network until the path is switched can be adjusted by changing the value of the frame non-arrival time until the path failure is detected. For example, as shown in FIG. 10, when the CC frame transmission interval is 500 ms and the frame non-delivery time is set to 1.5 s (corresponding to three CC frame non-delivery times), switching is performed within 2 seconds after a failure occurs in the network. Can be completed. FIG. 10 is a table showing an example of the network switching completion time in the embodiment of the network redundant system of the present invention.

  As shown in FIG. 10, even if the CC frame transmission interval is 1 s and the frame non-delivery time is 5 s (corresponding to 5 CC frame non-delivery times), it takes about 5 seconds from the occurrence of a failure in the network to the completion of switching. Can be suppressed.

  Next, with reference to FIG. 6 described above, the operation when a failure occurs in the path between the transmitting terminal device A of the accommodation station and the center station switch W1 will be described in detail. As shown in FIG. 6, a fault 601 has occurred in the path between the transmitting terminal A of the accommodation station and the center station switch W1.

  Due to the failure 601 in the route, the active route is disconnected. Due to the disconnection of the active route, the receiving end device of the accommodation station stops receiving frames from the active route, and the user frame or CC frame that has been normally received until then is no longer received. Start measuring dead time.

  Upon receiving the timeout of the active reception timer that measures the frame non-arrival time, the receiving end device of the receiving station recognizes the active route as an abnormal state, performs switching by 1 + 1 protection, The system path is switched (S601). However, if the receiving end device normally receives even one frame before the active reception timer reaches time-out, the receiving end device does not detect a path abnormality and does not perform switching.

  The receiving end device recognizes the previous standby path as the new operating path by switching the path (for convenience, the redundant system before switching is made the old operating system and the old standby system, and after switching Are called the new operational system and the new standby system), and the received frame discarded until then is transmitted to the user terminal.

  The receiving end device discards the frame after analyzing the frame from the old standby path, and recognizes that no failure has occurred in the old standby path. After the switching is completed, the receiving end device of each accommodating station multicasts the switching notification frame.However, in this failure, the receiving end devices of all the accommodating stations have completed switching due to a frame non-delivery timeout, and the switching notification frame is triggered. The receiving end device transmits a switching response frame again.

  When the failure of the new standby system recovers, the receiving end device starts to normally receive the frame again, and the receiving end device of the accommodating station confirms the failure recovery of the new standby system. However, since the path switching is not performed in the 1 + 1 protection, even if the failure of the new standby system is recovered, the receiving end device does not perform switching again.

  Next, patterns other than the failure shown in FIG. 6 will be described. As failure patterns other than those described above, there are three possible patterns: an operational switch device failure, a standby route failure, and a standby device failure.

In FIG. 11, in one embodiment of the network redundant system of the present invention, the occurrence of a device failure of the active switch is detected between the transmitting end device A and the receiving end device B, and the receiving end device C and the receiving end device Schematic diagram when D performs network switching triggered by reception of a switching notification frame.

  The transmitting end device A of the accommodation station receives the frame from the user and transmits the user frame, or multicasts the CC frame along the frame transmission timer (S1101). When a device failure of the active switch 1101 occurs, the transmitting end device A and the receiving end device B are in a non-communication state as in the case of a path failure, and the frames transmitted / received between the devices in the accommodation station are also in a non-conduction state. become.

  When the frame disconnection timer times out, the receiving end device performs path switching in the same procedure as the line failure (S1102). The transmission end device A and the reception end device B that have been notified of the failure of the active system switch via the standby path from the reception end device B multicast the switch notification frame after completing the switching. Here, in the switching notification frame transmitted by the transmitting end device A, the switching notification bit and the switching response bit are described. The receiving end device C and the receiving end device D perform path switching when receiving the switching notification frame (S1103). With the above operation, switching of the entire network is completed.

  Here, the network switching shown in FIG. 11 will be described with reference to FIG. 12 by dividing the operation when a frame is transmitted from the receiving end apparatus B by route. FIG. 12 shows the relationship between the receiving end device B and the transmitting end device A, and the receiving end device B, the receiving end device C, and the receiving end device D when a network switch failure occurs in the network switching shown in FIG. 12A is a schematic diagram of an operation for switching between networks. FIG. 12A is a diagram illustrating an operation between the receiving end device B and the transmitting end device A when an in-network switch failure occurs in the network switching illustrated in FIG. FIG. 12B is a schematic diagram of the operation of switching the network of the receiving end device B, the receiving end device C, and the receiving end device when a network switch failure occurs in the network switching shown in FIG. It is the schematic of the operation | movement which switches the network between D.

  As shown in FIG. 12A, when the operation system switch 1201 fails, the operation system line breaks, and the frame is not received between the transmission end device A and the reception end device B, and the transmission end Switching is performed between the device A and the receiving end device B. Next, as shown in FIG. 12B, switching is performed when the receiving end device C and the receiving end device D receive the switching notification frame from the receiving end device B, and the receiving end device C and the receiving end device C receive it. The terminal device D transmits a switching completion frame.

(If a failure occurs in the standby system)
Next, in the embodiment of the network redundant system of the present invention, a case where a failure occurs in the standby system will be described with reference to FIG. FIG. 13 is a schematic diagram when a failure occurs in the standby system in one embodiment of the network redundant system of the present invention.

  As shown in FIG. 13, when a failure occurs in the standby system, the reception end device of the accommodating station detects an abnormality in the standby system from the timeout of the frame non-arrival timer. Does not switch. The receiving end device continues communication in the active system while recognizing the failure state of the standby system. When the failure of the standby system is recovered, the receiving end device normally receives the frame and detects the recovery of the failure of the standby system path.

As described above, according to one embodiment of the network redundancy system of the present invention, a device having a CC scheme and 1 + 1 protection is installed in a receiving station that accommodates user terminals, and relay stations (center stations, aggregation stations, etc.) Two switches for the active system and the standby system are installed in the network, and the operation path and the standby system path of the accommodation station are connected to the operation switch and the standby system switch of the relay station, respectively. It is possible to construct a network redundancy by dividing a route between accommodated user terminals into an active system and a standby system. Therefore, in this embodiment, it is not necessary for the relay station other than the accommodating station that accommodates the user terminal to have the CC scheme and 1 + 1 protection, and it is not necessary for all devices configuring the network to have the CC scheme and 1 + 1 protection.

  In other words, the present embodiment can be configured regardless of the type of switch used other than the accommodating station that accommodates the user terminal. In addition, the present invention conforms to the IEEE recommendation and is not an extension of the IEEE recommendation. Therefore, it is possible to add functions to a conventional network and easily expand the functions.

  Also, in this embodiment, the transmission end device transmits the same frame to both the active system and the standby system, and the receiving end device receives from both systems by the 1 + 1 protection Distribute function and the Selector function of the device of the accommodation station. Of the frames, the frame from the standby system is discarded in the apparatus, and only the frame from the operation system is allowed to pass. With this function, in this embodiment, no loop occurs in the active system and the standby system.

  In other words, the present embodiment solves the network loop problem by the network redundancy of the communication network in which the apparatus having the 1 + 1 protection function and the CC method is used as the user terminal accommodation station. Thereby, this embodiment can give high operability and reliability to a network by the network redundancy of the communication network which used the apparatus which has a 1 + 1 protection function and CC system for the accommodation station of a user terminal.

  In this embodiment, after transmission of a user frame from the transmitting end device of the accommodation station is stopped, the normality of the route is confirmed by multicast transmission of a CC frame as a control frame triggered by a timeout of the frame transmission timer. To do. The receiving end device of the accommodation station confirms the normality of the route by normal reception of the user frame and CC frame. When an abnormality occurs in the route, the receiving end device of the accommodation station measures the frame non-delivery time, and the route is regarded as a failure state when the frame non-delivery time is timed out. For this reason, in the present embodiment, it is possible to reduce the influence on network traffic in order to detect a communication interruption.

  Further, in this embodiment, when a path failure is detected by the receiving end device of the accommodation station and the corresponding route is the active system, the receiving end device switches between the active system path and the standby system path. Upon completion of the switching, the receiving end device multicasts a switching notification CC frame to other accommodating station devices, and each device that receives this immediately switches between the active route and the standby route. carry out.

  That is, the present embodiment solves the high-speed switching of the network by the network redundancy of the communication network using the apparatus having the 1 + 1 protection function and the CC method as the user terminal accommodating station. Thereby, this embodiment can give high operability and reliability to a network by the network redundancy of the communication network which used the apparatus which has a 1 + 1 protection function and CC system for the accommodation station of a user terminal.

  In addition, according to an embodiment of the network redundant system of the present invention, the entire path can be switched in a short time. The receiving end device of each accommodation station detects the recovery of the route at the time when one normal CC frame is received after detecting the abnormal state of the route.

  For example, in the network redundant system of the present embodiment, since it is about 50 msec from when the receiving end device detects a path abnormality until the switching is completed, when the frame non-arrival timer is set to 1.5 sec, The time from when an abnormality occurs in the network until the path switching is completed is about 1.5 seconds. When network switching is performed by the conventional method, it takes about 1 to about 10 minutes or more, so that the switching time can be greatly improved by this embodiment.

(Appendix 1)
A sending terminal connected to multiple routes,
A measuring means for measuring a time during which data is not transmitted to the route;
A transmission terminal comprising: determination data transmission means for transmitting data for determining communication interruption to the plurality of paths when the time measured by the measurement means exceeds a predetermined time.

(Appendix 2)
A receiving terminal that accommodates user terminals connected to a plurality of routes,
Measuring means for measuring the non-delivery time of data from the route;
A receiving terminal comprising switching means for switching a path using received data from the plurality of paths when the time measured by the measuring means exceeds a predetermined time.

(Appendix 3)
A transmission terminal that accommodates a user terminal that transmits data to both the first route and the second route, and is a time during which data is not transmitted to the first route and the second route. A transmitting terminal for measuring and transmitting data for determining communication interruption to the first route and the second route when the measured time exceeds a predetermined time;
Connected by the transmitting terminal, the first route and the second route;
Whether the data non-delivery time is measured, and when the measured data non-delivery time exceeds a predetermined time, whether data received from the first route or data received from the second route is used A network redundant system comprising: a receiving terminal that accommodates a user terminal.

(Appendix 4)
The receiving terminal is
When the non-delivery time of the data from the route that used the received data exceeds the predetermined time, switch the route that did not use the received data to the route that uses the received data,
The data non-arrival time from the route that did not use the received data exceeded a predetermined time, and the data non-delivery time from the route that used the received data exceeded the predetermined time The network redundant system according to supplementary note 3, wherein the switching of the route is not performed when the non-delivery time of the data from the route not using the received data exceeds a predetermined time.

(Appendix 5)
In the receiving terminal, when the switching occurs,
The network redundancy system according to supplementary note 3, wherein the receiving terminal transmits data indicating that the switching has occurred to the network so that the switching is performed in another receiving terminal configuring the network.

(Appendix 6)
The receiving terminal is
4. The network redundant system according to appendix 3, wherein it is confirmed whether data is received from a path that does not use the received data.

(Appendix 7)
The receiving terminal is
4. The network redundant system according to appendix 3, wherein data from a path not using the received data is discarded.

It is the schematic of the transmission operation | movement of CC frame in one Embodiment of the network redundant system of this invention. It is the schematic of the switching system by 1 + 1 protection in one Embodiment of the network redundant system of this invention. It is the schematic of the construction example of one Embodiment of the network redundant system of this invention. It is the schematic which put together the construction example of one Embodiment of the network redundant system shown by FIG. 3 for every user. It is the schematic of the internal structure of a transmission terminal device and a receiving terminal device used for one Embodiment of the network redundant system of this invention. FIG. 3 is a schematic diagram when a failure occurs in the constructed network path in an embodiment of the network redundancy system of the present invention. It is the schematic of the frame format of CC frame used in one Embodiment of the network redundant system of this invention. It is a table | surface which shows the definition of the Status field of CC frame shown by FIG. 6 is a flowchart showing a procedure for system switching due to non-arrival of a frame in a receiving end device in an embodiment of the network redundant system of the present invention. It is a table | surface which shows an example of the network switch completion time in one Embodiment of the network redundant system of this invention. In one embodiment of the network redundant system of the present invention, the occurrence of a device failure of the active switch is detected between the transmitting end device A and the receiving end device B, and the receiving end device C and the receiving end device D notify the switching. It is the schematic in the case of performing network switching triggered by reception of a frame. In the network switching shown in FIG. 11, the network between the receiving end device B and the transmitting end device A and the receiving end device B, the receiving end device C, and the receiving end device D when an in-network switch failure occurs. It is the schematic of the operation | movement which switches. FIG. 2 is a schematic diagram when a failure occurs in a standby system in an embodiment of the network redundant system of the present invention. It is the schematic of the network redundant system using STP. It is the schematic of the operation | movement of the conventional CC system.

Explanation of symbols

500 Transmission end device (transmission terminal)
501 Transmission check unit 502 Transmission timer (measurement means)
503 CC frame transmission unit (determination data transmission means)
504 Distribution section 505 Active system check section 506 Standby system check section 507 Operation system reception timer (measurement means)
508 Preliminary reception timer (measurement means)
509 Frame analysis unit 510 Selector function unit (switching means)
511 CC frame transmission unit 512 reception end device 513 active system route 514 standby system route 515 transmission unit 516 reception unit 517 transmission unit

Claims (1)

It includes at least a transmitting end device, a first receiving end device, and a second receiving end device that can accommodate user terminals, respectively, between the transmitting end device and the first receiving end device, and between the transmitting end device and the second receiving end device. during the network redundant system for connecting at least two of the first path and second path respectively,
Connected to the transmitting end device via one path constituting the first route, and connected to the first receiving end device and the second receiving end device via different paths constituting the first route. A first switch,
Connected to the transmitting end device via one path constituting the second route, and connected to the first receiving end device and the second receiving end device via different paths constituting the second route. A second switch,
With
The transmitting end device is
Transmitting means for transmitting user data to both the first route and the second route;
Measuring means for measuring time during which user data is not transmitted to the first route and the second route;
When the user data non-transmission time measured by the measuring means exceeds a predetermined time, the continuation confirmation data is stored so that the first receiving end device or the second receiving end device does not determine that the communication is interrupted due to data non-delivery. Continuation confirmation data transmitting means for transmitting to the first route and the second route at regular time intervals until transmission of user data is resumed;
Including
The first receiving end device and the second receiving end device are respectively
Receiving means for receiving user data or continuation confirmation data from the first route and the second route;
Data selection means for transmitting only user data received from the first route to user terminals among user data received by the receiving means;
Measuring means for measuring a data non-delivery time in which neither user data nor continuation confirmation data is received from the first route and the second route;
When the data non-delivery time measured by the measuring means exceeds a predetermined time, the usage route of user data for transmission to the user terminal is switched from the first route to the second route.
Switching means,
Including
The first receiving end device is
A failure occurs in a route between the first switch and the first receiving end device constituting the first route, and a use route of user data for transmission to the user terminal by the switching unit is changed from the first route to the first route. When switched to the second path, the occurrence of a failure in the first path is transmitted to the transmitting end apparatus via a path between the second switch and the first receiving end apparatus constituting the second path. A notification means for notifying;
The transmitting means of the transmitting end device is
When the occurrence of a failure in the first route is notified from the first receiving end device, multicast transmission of data indicating that switching has occurred to both the first route and the second route,
The switching means of the second receiving end device transmits data indicating that the multicast transmission from the transmitting end device has occurred between the second receiving end device constituting the first path and the first switch. The user data used for transmission to the user terminal is switched from the first route to the second route when received via the route.
A network redundant system characterized by that.

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