JPH10145408A - Bypass control system for ring type transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an error in selecting a reception path based on circulation of communication data at node bypass in a double ring type transmitter that selects 2-way simultaneous transmission/reception paths. SOLUTION: Each of a plurality of nodes on a duplicate ring transmission line is provided with duplicate transmission line interface circuits 20 , 21 , duplicate bypass circuits 30 , 31 and duplicate cross connect circuits 40 , 41 , a terminal interface circuit 5 is provided with a reception path selection circuit 6 that selects a not faulty transmission line in the duplicate lines when a parity abnormality in received data is detected, each node sends same data to the two transmission lines and selects a reception path to receive data of an opposite node. In the transmission system as above, in the case of bypassing a bypass circuit, transmission of communication data is stopped and invalid data are sent to the transmission line and the bypass position is selected and a reception path selection circuit of the opposite node selects a normal path through the detection of a parity abnormality in the received data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ring type transmission apparatus, and more particularly to a bypass control method for a ring type transmission apparatus which prevents an error in selection of a receiving route based on data circulation in a duplex ring type transmission apparatus. It is.

[0002] In a duplex ring type transmission apparatus, in order to shorten the instantaneous interruption time of communication due to switching of transmission paths,
There is a method of transmitting communication data to both transmission paths on the transmission side, checking the normality of the communication data on the reception side, and selecting a transmission path to receive.

In such a ring type transmission device,
In both of the opposing nodes, when the bypass setting is performed for one system of the transmission line, the same communication data circulates on the transmission line, and it is possible to prevent the selection of the reception route from being performed normally, thereby preventing the system from being incorrectly selected. It is necessary to increase reliability.

[0004]

2. Description of the Related Art FIG. 5 shows a schematic configuration of a ring transmission apparatus. In the ring transmission apparatus, as shown in the figure, a plurality of nodes are arranged on a duplex transmission line composed of a # 0 system and a # 1 system, which are in opposite directions.

[0005] In a ring-type transmission apparatus, as shown in FIG. 5, redundancy is enhanced by providing ring-type transmission paths in duplicate so as to be opposite to each other. In a duplex ring transmission device, communication is normally performed using one transmission line, and when a failure occurs, switching to the other transmission line is performed to perform system reliability. There is a way to increase.

Further, in order to shorten the instantaneous interruption of communication due to the switching of transmission paths, the transmission side transmits communication data to both transmission paths and duplicates up to the reception-side cross-connect circuit. A method of checking the normality of communication data by a terminal interface circuit and selecting a transmission line to receive is used in part.

[0007] Figure 6 is a shows the basic configuration of a node in the ring type transmission device two-way path simultaneous transmission / reception route selection scheme, 1 controller, 2 _0, 2 ₁ transmission line interface circuit (transmission line IF), 3 _0, 3 ₁ bypass circuit, 4 _0, 4 ₁ cross-connect circuit, 5 is a terminal interface circuit (terminal IF). In the terminal interface circuit 5, reference numeral 6 denotes a reception route selection circuit, and reference numeral 7 denotes a communication data generation circuit. In the following, the duplicated portions including the transmission path and operating independently of each other are referred to as systems. For example, when one transmission line is described, it is described as one system, and when both transmission lines are described, it is described as both systems.

FIG. 7 exemplifies a format of communication data in the ring type transmission device. The communication data includes a data time slot and a control information time slot, and the control information time slot includes a direction bit DIR indicating a transmission direction and a parity bit PTY. The calculation range at the time of parity generation is a data time slot and a control information time slot excluding a parity bit.

The control circuit 1 monitors the state of the node.
Function of each cross-connect circuit and communication path between each circuit
When an abnormality is detected in the bypass circuit 3₀Also
Is 3 ₁Perform a function of transitioning to a bypass state. Again
The control circuit 1 checks whether there is a fault according to the operation of the maintenance person.
It has a test function to transition to bypass state
I have.

On the transmitting side of the terminal interface circuit 5,
Communication data received from the terminal in time slot units
Divide and add parity and direction bits indicating transmission direction
And prepare communication data in the format shown in FIG.
And the cross connect circuit 4_0,4 ₁To send to.

The parity bit is added to the communication data in order to check the normality of the communication data.
Also, the direction bit is set so that when the communication data transmitted by the own node goes around the transmission path and returns to the own node, it can be determined in consideration of the case where the communication partner node is bypassed. The received data having the same direction bit as that transmitted by the own node is determined to be abnormal.

On the receiving side of the terminal interface circuit 5,
The communication data received from the cross-connect circuit 4 _0, 4 ₁ of both systems, performs inspection of parity and the direction bit,
If the communication data of the previously selected system is normal, reception is performed from the same system as is, and if an error is detected in the communication data of the previously selected system, the communication data of the other system is detected. If is normal, the system is switched to perform reception.

[0013] In the cross-connect circuit 4 _0, 4 _1, performs a cross-connect communications data of the time slot unit, to realize a communication path between terminals.

FIG. 8 shows a configuration example of a conventional control circuit, bypass circuit, and cross-connect circuit.
In the control circuit 1, reference numeral 11 denotes a judgment circuit. In the bypass circuit 3, 12 is a relay buffer, 13 is an access control memory (ACM), 14 is a selector,
Reference numeral 15 denotes a mask circuit. In the cross connect circuit 4, reference numeral 16 denotes a time switch (TSW).

In the bypass circuit 3, the mask circuit 15 normally has the access control memory 13
Is transmitted to the selector 14. The access control memory 13 is set with selection information for controlling the selection of the selector 14. By reading the set value of the access control memory 13 and switching the selector 14 in synchronization with the read timing on the transmission line interface circuit side, the selector 14 performs time slot relaying by the bypass circuit in accordance with this selection information. Is switched to the 0 side to select the transmission line interface circuit side, and the time slot transmitted from the own node is switched to the 1 side to select the cross connect circuit side, so that communication during normal operation is performed. Do.

In the cross-connect circuit 4, the time switch 16 takes in communication data from the transmission line interface circuit into the terminal interface circuit in a predetermined time slot, and transfers communication data from the terminal interface circuit to the transmission line. Send it to the interface circuit side.

FIG. 9 explains the erasure of communication data at the receiving station. In the case of one-to-one communication, opposing nodes are set to communicate using the same time slot. The communication data transmitted from the node including the terminal A is received by the node including the terminal B that is opposed to the ring-type transmission line by halfway. Communication data is transmitted from the node including the terminal B to the node including the terminal A using the same time slot.

As described above, the time slot to which the communication data transmitted from one node is assigned is rewritten by the communication data transmitted from that node in the bypass circuit of the opposing node.
The receiving station is erased.

In the control circuit 1, the judgment circuit 11
Outputs a mask signal when various alarms are generated based on a failure or when a test is set. When the mask signal is output from the control circuit 1, the selector 14 always outputs 0.
Side, the output of the relay buffer 12 is selected and output to the transmission line interface circuit side irrespective of the setting of the access control memory 13, so that the failure in the node is prevented from spreading to the entire system. Works.

The transmission line interface circuit assembles / disassembles a transmission frame and realizes communication with other nodes via the transmission line.

Thus, in the conventional system,
A bypass circuit is provided so that the effect of a failure at each node does not spread to other nodes. The failed node operates to relay the communication data from the upstream node without transmitting the communication data from the own node. Further, the node always performs reception regardless of whether the node is in the bypass state.

As for the bypass function, for each transmission path,
Work independently. In other words, even if the bypass operation is performed on the abnormal transmission path, if the other transmission path is normal, the normal transmission path performs the normal operation without performing the bypass.

[0023]

In a conventional system, for example, when a bypass setting is made for the same system in a transmitting node while one of the nodes of a communication partner is experimentally set to be bypassed. Has no node that erases the last transmitted communication data,
The same communication data circulates on the transmission path.

At this time, the transmission source node detects the abnormality by checking the direction bit, and switches to another system to receive the signal. However, the other node has no abnormality in the direction bit and the parity. Therefore, there is a problem that the system cannot be switched to a normal system.

An object of the present invention is to solve such a problem of the prior art. In a duplex ring transmission apparatus, when each node has a bypass function, one system of a communication partner node is used. When the bypass setting is performed for the same system in the transmitting node while the bypass setting is being performed for the same communication data, the same communication data circulates on the transmission path, so that the reception path selection is not performed properly It is an object of the present invention to provide a ring-type transmission device bypass control method that can prevent the above problem.

[0026]

[MEANS FOR SOLVING THE PROBLEMS] The principle configuration of the present invention (1)
In, a mask circuit is provided in an output stage of a cross-connect circuit to a bypass circuit, and a timing circuit is provided in a control circuit.

If the decision circuit in the control circuit decides to bypass, a bypass instruction is sent to the timing circuit in the control circuit and the mask circuit in the cross-connect circuit. Stops, and invalid data is transmitted to the transmission path.

On the receiving side, the invalid data is detected as a parity error, and the receiving route selection circuit in the terminal interface circuit operates to select another route. Next, the bypass instruction temporarily held by the timing circuit is input to the bypass circuit, the setting of the access control memory is invalidated, and the communication data stored in the relay buffer is transmitted to the transmission line interface circuit for all timings. And the node shifts to the bypass state.

In the principle configuration (2) of the present invention, a mask circuit is provided at the output stage of the bypass circuit on the cross-connect circuit side, and the output to the cross-connect circuit is provided according to the bypass instruction from the control circuit. Try to shut it off. As a result, the system in the bypass state receives invalid data, so that the terminal interface circuit operates so that the reception route selection circuit switches the reception route to the other system.

In the principle configuration (3) of the present invention, a signal is provided from the control circuit to the terminal interface circuit to notify whether or not each system is in the bypass state. The reception route selection circuit in the terminal interface circuit adds the presence / absence of a bypass state to the selection condition in addition to the parity check result of the communication data and the consistency bit result of the route bit for each route.

The route selection condition includes, in addition to the conventional condition that switching is performed when "the currently selected system has an error in parity or direction bit and the system to be switched to is normal", Switching is performed when "the parity and direction bit are normal in both systems, the currently selected system is in the bypass state, and the system on the switching side is not bypassed."

Hereinafter, specific means and actions for solving the problems of the present invention will be described.

[0033] (1) a plurality of nodes arranged in duplexed ring transmission line, the transmission line interface circuit 2 ₀ is duplicated to interface with respect to each transmission path is _duplicated, 2 ₁ a, the transmission Bypass circuit 3 for bypassing the node side of the circuit interface circuit
_0, 3 _1, provided with a cross-connect circuit 4 _0, 4 _1, which is duplexed selectively connects the terminal to the transmission path corresponding through each transmission path interface circuits, and each cross-connect circuit and the terminal The terminal interface circuit 5 which takes the interface of the above has a reception path selection circuit 6 for selecting a normal side of the duplexed transmission path as a reception path when a parity error of received data is detected, and a ring type transmission path from each node. In a transmission device that simultaneously transmits the same data to two routes and selects a receiving route to receive data of a partner node, when a bypass is performed in one of the bypass circuits, a communication in which the own node is a transmission source. By stopping data transmission, sending invalid data on the corresponding transmission path, and then switching to the bypass side, the destination node , Receiving ports selection circuit switches the normal route through the detection of a parity abnormality of the received data.

By doing so, it is possible to prevent the communication data transmitted from the node that has shifted to the bypass state from remaining on the transmission path, so that both of the communicating opposing nodes are in the bypass state. Also, since the old communication data that continues to circulate is not erroneously recognized as normal communication data, the reception route selection is performed normally.

(2) In the case of (1), a timing circuit 18 for controlling the stop of communication data transmission for a predetermined time is provided, and after the predetermined time has elapsed, a bypass is executed in the bypass circuit.

By doing so, the bypass can be correctly performed in the bypass circuit by executing the bypass after a preset predetermined time.

(3) In the case of (2), the predetermined control time of the timing circuit 18 should be set to a time interval at which the receiving node can reliably execute the switching of the receiving route and the instantaneous interruption is not detected by the upper layer protocol. Or a time interval corresponding to the transmission delay time for one round of the ring.

By doing so, the transmission stop time of the communication data is set to a time interval at which the receiving node can reliably execute the switching of the receiving route and the instantaneous interruption is not detected by the upper layer protocol, and the bypass is set. Can do it correctly. Alternatively, this time can be set to the transmission delay time for one round of the ring so that communication data before the occurrence of the bypass factor does not remain on the transmission path.

[0039] (4) in a plurality of nodes arranged in duplexed ring transmission path, the transmission path interface circuit 2 _0, 2 _1, which is duplexed to interface to each transmission path is duplicated, each transmission Bypass circuit 3 for bypassing the node side of the circuit interface circuit
_0, 3 _1, provided with a cross-connect circuit 4 _0, 4 _1, which is duplexed selectively connects the terminal to the transmission path corresponding through each transmission path interface circuits, and each cross-connect circuit and the terminal The terminal interface circuit 5 which takes the interface of the above has a reception path selection circuit 6 for selecting a normal side of the duplexed transmission path as a reception path when a parity error of received data is detected, and a ring type transmission path from each node. In a transmission device that simultaneously transmits the same data to two routes and selects a receiving route to receive the data of the partner node, during bypass in any one of the bypass circuits, from the bypass circuit to the corresponding cross-connect circuit By masking outgoing communication data and making it invalid data, the receiving route selection circuit can detect the parity error of the received data. It switches to route normal by out.

By doing so, even if both communicating nodes are in the bypass state and communication data remains on the transmission line, the communication data does not reach the terminal interface circuit. , The receiving route selection is executed normally.

[0041] (5) in a plurality of nodes arranged in duplexed ring transmission path, the transmission path interface circuit 2 _0, 2 _1, which is duplexed to interface to each transmission path is duplicated, each transmission Bypass circuit 3 for bypassing the node side of the circuit interface circuit
_0, 3 _1, provided with a cross-connect circuit 4 _0, 4 _1, which is duplexed selectively connects the terminal to the transmission path corresponding through each transmission path interface circuits, and each cross-connect circuit and the terminal A terminal interface circuit 5 for interfacing with a receiving path selecting circuit 6 for selecting a normal side of a duplexed transmission path as a receiving path when detecting an error in a direction bit or parity of received data, and a ring from each node. In the transmission apparatus for simultaneously transmitting the same data to two paths of the type transmission path and selecting the reception path to receive the data of the partner node, the presence / absence of bypass in any one of the bypass circuits is determined by the reception path selection circuit 6. When the communication data received from each transmission path is both normal, the reception path selection circuit 6 does not To select a route.

By doing so, both of the communicating nodes are in the bypass state.
Even if communication data remains on the transmission path, normal (not bypassed) communication data is selected preferentially when the receiving route is selected, so that old communication data that continues to circulate normally can be used. It can be prevented that the communication route is incorrectly recognized and the receiving route selection is not performed normally.

(6) In the case of (5), the terminal interface circuit has a parity check circuit 21 _0, 21 ₁ for checking the parity of each route, and a direction bit check circuit for checking the direction bit of the received data. 22 _{0 and} 22 ₁ are provided, and when both the inspection results are normal, it is determined that the received data is normal.

By doing so, it can be reliably detected that both the communication data received from each transmission path are normal.

[0045]

FIG. 1 shows an embodiment (1) of the present invention, in which an output control function is added to a cross-connect circuit, and the same elements as those in FIG. The numbers are shown. Reference numeral 17 denotes a mask circuit provided in the cross-connect circuit 4, and reference numeral 18 denotes a timing circuit provided in the control circuit 1.

When various alarms or test instructions are generated based on a fault, the determination circuit 11 in the control circuit 1 determines whether or not the cause is a bypass factor, and issues a bypass instruction to the cross-connect circuit 4. In the cross-connect circuit 4, the mask circuit 17 responds to the bypass instruction by the time switch 1
Cut off the output from 6.

As a result, of the communication data transmitted from the bypass circuit 3 to the transmission line interface circuit, invalid data is inserted into the time slot allocated for transmission from the own node. On the other hand, the valid data read from the relay buffer 12 is inserted into the time slot allocated to relay.

The node that receives the communication data from the bypassed node detects invalid data as a parity error. Therefore, the receiving route selection circuit switches the receiving system from the system bypassed on the other side to the other system. Operates to switch the road.

In this way, at the partner node,
After sending invalid data for a certain period of time, the timing circuit 18 in the control circuit 1 times out and issues a bypass instruction to the bypass circuit 3 so that the receiving path switching is executed reliably.

The timeout period of the timing circuit 18 is designed in consideration of a time interval in which the receiving node can reliably perform the switching of the receiving route, and a momentary interruption is not detected by the upper layer protocol. For example, a bypass instruction is held for 50 ms and then issued. Alternatively, the bypass instruction may be held for the transmission delay time for one rotation of the ring so that communication data before the occurrence of the bypass factor does not remain on the transmission path.

FIG. 2 shows an embodiment (2) of the present invention, in which an output control function is added to a bypass circuit, and the same components as those in FIG. 1 are indicated by the same reference numerals. . 19 is a mask circuit provided in the bypass circuit 3.

When a bypass instruction is issued from the determination circuit 11 of the control circuit 1, the setting of the access control memory 13 of the bypass circuit 3 is invalidated by the mask circuit 15, and the relay buffer 12
Is transmitted to the transmission line interface circuit, and the node shifts to the bypass state.

At the same time, the masking circuit 19 at the output stage of the bypass circuit 3 on the cross-connect circuit side masks the output, and invalid data is sent to the cross-connect circuit 4. As a result, the terminal interface circuit receives the invalid data, so that a parity error is detected, and the reception route selection circuit operates to switch the reception route to the other system.

FIG. 3 shows an embodiment (3) of the present invention, and shows the configuration of a terminal interface circuit in which a bypass state is selected. In the figure, 21 _0, 21
₁ parity check circuit, 22 _0, 22 ₁ Direction bit test circuit, 23 determination circuit, 24 denotes a selector, 25 is a driver circuit. The selector 24 and the driver circuit 25 make up the receiving path selection circuit 6 shown in FIG. FIG. 4
Indicates the truth value of the determination condition of the receiving route selection circuit.

When there is no failure in the transmission line and the cross-connect circuit and the bypass state is forcibly set by the test setting, normal communication data reaches the terminal interface circuit from both systems. For example, if the # 0 system is currently selected, and if the # 0 system is forcibly set to the bypass state in the test setting, the inspection results on the parity and the direction bit indicate that both systems are normal. You.
However, since the control circuit notifies the determination circuit 23 that the # 0 system is in the bypass state, the system is switched to the # 1 system according to the determination condition truth value of FIG.

[0056]

As described above, according to the present invention, in a duplex ring transmission apparatus, when a bypass function is provided for each node, the bypass setting is performed for one system of the communication partner node. Thus, when bypass setting is performed for the same system in the transmission-side node, it is possible to prevent the same communication data from circulating on the transmission path and preventing the reception path from being selected normally.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment (1) of the present invention.

FIG. 2 is a diagram showing an embodiment (2) of the present invention.

FIG. 3 is a diagram showing an embodiment (3) of the present invention.

FIG. 4 is a diagram illustrating truth values of determination conditions of a reception route selection circuit.

FIG. 5 is a diagram illustrating a schematic configuration of a ring transmission device.

FIG. 6 is a diagram showing a basic configuration of a node in a ring transmission apparatus of a two-way simultaneous transmission / reception route selection system.

FIG. 7 is a diagram illustrating a format of communication data in a ring transmission device.

FIG. 8 is a diagram showing a configuration example of a conventional control circuit, bypass circuit, and cross-connect circuit.

FIG. 9 is a diagram illustrating erasure of communication data in a receiving station.

[Explanation of symbols]

2 ₀ Transmission line interface circuit 2 ₁ Transmission line interface circuit 3 ₀ Bypass circuit 3 ₁ Bypass circuit 4 ₀ Cross connect circuit 4 ₁ Cross connect circuit 5 Terminal interface circuit 6 Receiving route selection circuit 18 Timing circuit 21 ₀ Parity check circuit 21 ₁ Parity check circuit 22 ₀ direction bit check circuit 22 ₁ direction bit check circuit

Claims (6)

[Claims] 1. A plurality of nodes arranged on a duplicated ring transmission line, a duplicated transmission line interface circuit interfacing with each of the duplicated transmission lines, and a node of each transmission line interface circuit. A dual bypass circuit that bypasses the side, and a dual cross-connect circuit that selects and connects a terminal to a corresponding transmission line via each transmission line interface circuit, and each cross-connect circuit and the terminal A receiving path selection circuit that selects a normal side of the duplexed transmission path as a reception path when a parity error of received data is detected in a terminal interface circuit that takes an interface of the ring type transmission path from each node. The same data is transmitted simultaneously to two routes, and the receiving route is selected to select the destination node's data. In the transmission device for receiving data, when performing bypass in any one of the bypass circuits, the own node stops transmission of communication data as a transmission source, and bypasses after transmitting invalid data on a corresponding transmission path. A bypass control method for a ring-type transmission device, characterized in that, by switching to the side, the receiving path selection circuit switches to a normal path upon detection of a parity error in received data at the partner node. 2. A bypass control method for a ring transmission apparatus according to claim 1, further comprising a timing circuit for controlling a stop of communication data transmission for a predetermined time, and executing a bypass in said bypass circuit after the predetermined time has elapsed. A bypass control method for a ring-type transmission device. 3. The predetermined control time of the timing circuit is:
The receiving node switching can be executed reliably by the partner node, and the time interval is such that the instantaneous interruption is not detected by the upper layer protocol, or the time interval corresponds to the transmission delay time for one round of the ring. A bypass control method for a ring-type transmission device according to claim 2. 4. A plurality of nodes arranged on a duplicated ring transmission line, a duplicated transmission line interface circuit interfacing with each of the duplicated transmission lines, and a node of each transmission line interface circuit. A dual bypass circuit that bypasses the side, and a dual cross-connect circuit that selects and connects a terminal to a corresponding transmission line via each transmission line interface circuit, and each cross-connect circuit and the terminal A receiving path selection circuit that selects a normal side of the duplexed transmission path as a reception path when a parity error of received data is detected in a terminal interface circuit that takes an interface of the ring type transmission path from each node. The same data is transmitted simultaneously to two routes, and the receiving route is selected to select the destination node's data. In a transmission device for receiving data, while bypassing in any one of the bypass circuits, the communication data transmitted from the bypass circuit to the corresponding cross-connect circuit is masked to be invalid data, so that the reception route selection circuit Switches to a normal path upon detection of a parity error in received data. 5. In a plurality of nodes arranged on a duplicated ring transmission line, a duplicated transmission line interface circuit that interfaces with each of the duplicated transmission lines, and a node of each transmission line interface circuit A dual bypass circuit that bypasses the side, and a dual cross-connect circuit that selects and connects a terminal to a corresponding transmission line via each transmission line interface circuit, and each cross-connect circuit and the terminal A receiving interface selecting circuit for selecting a normal side of the duplexed transmission path as a receiving path when detecting an abnormality in the direction bit or parity of the received data in a terminal interface circuit that takes an interface of the terminal interface circuit; The same data is transmitted simultaneously to two paths of the type transmission path, and the receiving path is selected. In the transmission device receiving the data of the partner node, by notifying the reception path selection circuit of the presence or absence of bypass in any of the bypass circuits, when both of the communication data received from each transmission path is normal, A bypass control method for a ring-type transmission device, wherein a receiving route selection circuit selects a receiving route that is not bypassed. 6. The bypass control method for a ring transmission apparatus according to claim 5, wherein the terminal interface circuit includes:
A parity check circuit for checking the parity of each route and a direction bit check circuit for checking the direction bit of the received data are provided, and when both check results are normal, it is determined that the received data is normal. A ring-type transmission device bypass control method.