JP2562896B2 - Node device and network monitoring device for irregular communication network - Google Patents

Description

TECHNICAL FIELD The present invention relates to control of a communication network, and more particularly to a node device and a network monitoring device of an irregular communication network.

2. Description of the Related Art As a communication network particularly applicable to multimedia communication such as a local area network (LAN) and a public line network, for example, Japanese Patent Application No. 61-218026 describes a multi-channel grid communication network based on the analogy of ecological nerve cells. Is proposed. In this method, a communication network is formed by connecting a communication control element of a multi-input and one-output signal as a node to a multi-coupling structure, and each node has a communication network form in which digital signals are transferred on a first-come-first-served basis.

This grid communication network is particularly excellent in the following points. One is the high degree of freedom of the network topology due to the multi-connection structure. Therefore, fault tolerance (survival) is high, that is, even if there is a failure in a part of the network, communication is adaptively secured by another route. Next, the first-come-first-served logic is used to select an optimum communication path. In addition, this system adopts a multi-channel system in which a plurality of connection channels are simultaneously established in a node, and efficiently establishes full-duplex communication. Such a grid communication network is effectively applied from the physical layer of OSI (Open System Interconnection) to the network layer.

When the fault tolerant property is emphasized in the grid communication network, it is important to reduce the influence of the failure and to detect the failure location quickly. There are three types of serious obstacles. The first is a failure of the node itself, the second is a failure of the transmission transmission path, and the third is a failure of the reception transmission path. In the above-mentioned grid communication network, the probability of communication being hindered by these first, second and third obstacles is very small.

In this way, it is possible to detect when a node or terminal ahead of a port exiting a node fails. However, if a broadcast is made to an address that does not actually exist in the network, or if a terminal or node oscillates, all nodes in the network continue to be in a broadcast state, which hinders new communication and is already set. I could not release the link.

It is an object of the present invention to solve the above drawbacks of the prior art and to provide a node device and a network monitoring device for an irregular communication network in which such an abnormal continuation of a broadcast state is avoided.

In order to achieve the above object, the present invention is a node device connected to a transmission line including a transmission line to a terminal or a node device and a reception line corresponding to the transmission line. At least one input means, at least one output means to which each transmission line is connected, connecting means for connecting the input means and the output means, and controlling the connecting means to selectively connect the input means to the output means In the node device of the irregular communication network having the control means for controlling, the control means controls the connecting means when the input means which is the earliest incoming signal to the terminal is identified among the input means, and the identified means is used. The forward signal is transferred from the input means to all output means other than the output means corresponding to the identified input means, and the control means controls the terminal by the input means other than the identified input means. When there is an input unit which receives the al for recovery signal,
The connecting means is controlled so that the input means receiving the return signal becomes the output means corresponding to the input means receiving the forward signal at the earliest, and the input means receiving the forward signal at the earliest. The output means corresponding to the input means receiving the recovery signal is connected to the input means to fix the connection between the input / output means, and the device further monitors at least one of the output means so that the output means keeps a predetermined period. It is characterized by a node device of an irregular communication network including a false signal sending means for sending a false signal to any of the input means when the outgoing signal is continuously sent beyond.

According to the present invention, also, a multi-input / single-output node device is connected to a multi-coupling structure, and in the node device, a transmission line to the node device of an amorphous communication network for transferring an input signal to an output by first-come-first-served logic and In a network monitoring device of an irregular communication network connected to a transmission line including a reception line corresponding to a transmission line, an input unit to which the reception line is connected, an output unit to which the transmission line is connected, and an input unit. A network monitoring device for an irregular communication network, which includes a false signal sending unit that sends a false signal as a return signal from the output unit when the forward signal continues for a predetermined length of time. To be done.

Hereinafter, the present invention will be specifically described based on examples.

An irregular communication network to which the node device according to the present invention is applied,
As illustrated in FIG. 7, the node device 10 is advantageously realized as a grid-shaped communication network in which two-dimensionally or three-dimensionally is connected by a transmission line 12 in a grid-like manner, but the network configuration is essentially indefinite. is there. For example, other shapes such as linear and loop shapes may be adopted.

The node device 10 is provided with a plurality of, in this example, eight input / output ports, to which other node devices 10 and / or terminals 14 can be connected via a transmission line 12.
There is no limit to the number of input / output ports, and it is sufficient if there is at least one. If the node device 10 is within the capacity of the input / output port, the node device 10 or the terminal connected via the transmission line 12
There is no limit on the number of 14. In addition, the entire network is a single node device
Alternatively, a plurality of node devices 10 may be mounted on a single printed wiring board, for example, and the entire device may be treated as one node device to substantially increase the input / output port capacity. Good.

The terminal 14 is a terminal device capable of asynchronously transmitting and receiving data in this embodiment, and includes a processing system such as a personal computer and a service station such as a file station and a print station. The data is advantageously transferred in the form of message packets. As will be described later, in the case of a full-duplex terminal, the terminal 14 which advantageously transmits a response signal immediately upon receiving a packet addressed to the terminal 14 is advantageously used.

In this lattice-shaped communication network, as shown by hatching in the figure, a communication network monitoring device 700 is connected to a specific transmission path 12 of a specific one of the node devices 10 at the same position as the terminal 14. This is a monitoring device that monitors a signal input to the transmission line 12 and returns a false signal to the transmission line 12 in a predetermined state. More specifically, the first forward signal on the transmission line 12 is monitored, and when this forward signal continues for a predetermined length of time, a false signal is set as a return signal and the transmission line 12
And has a function of establishing a link in the communication network. Several such communication network monitoring devices 700 are provided in the network, for example, one or more.

The transmission line 12 is, for example, an optical transmission line using an optical fiber or an electric transmission line such as a stranded wire or a coaxial cable. In the present embodiment, data is transmitted in analog or digital. It has a full duplex configuration. The transmission line 12 between the node device 10 and the terminal 14 may have a half-duplex configuration.
In addition, the transmission path between the node devices 10 depends on the traffic.
A plurality of 12 may be provided.

Referring to FIG. 1, the node device 10 has an input port 20 to which a reception line from the transmission line 12 is connected, and an output port 30 to which a transmission line to the transmission line 12 is connected. They are interconnected via a section 40. The input port 20 is eight receiving or input channels in this embodiment.
i0 to i7 and the output port 30 correspondingly has eight transmission or output channels o0 to o7. As a result, up to eight other node devices 10 and terminals 14 can be connected to the node device 10 via the transmission path 12. Of the output channels o0 to o7, the output channels having the same numbers as the input channels i0 to i7, that is, the "corresponding" output channels are connected to the transmission path 12 of the same route.

The switching gate unit 40 is a gate circuit that selectively interconnects any one of the input channels i0 to i7 and any one of the output channels o0 to o7. The input port 20 is also connected to a start control unit 60 and an end control unit 70 via a control gate unit 50. The control gate unit 50 is
The signal from the input port 20 is sent to the start controller 60 and the start controller
This is a gate circuit that appropriately controls connection of control signals from the failure control unit 210, the termination control unit 70, and the switching gate unit 40 and the termination control unit 70. The start control unit 60 is a functional unit that identifies the input channel from which the input signal arrives first and detects whether or not there is an input signal in each input channel. The termination control unit 70 is a circuit that detects that there is no input signal in the input channel of the communication path that has already been set, and performs termination processing of the communication. The switching gate unit 40, the start control unit 60, and the end control unit 70 are connected to each other by a gate set bus 80.

An active signal output unit 200 for sending an active signal is also connected to the switching gate unit 40,
This is also connected to the start controller 60. The start control unit 60 and the end control unit 70 are also connected to a fault storage unit 210 that stores a channel in which a fault has occurred. Fault memory 2
10 is also connected to the gate set bus 80.

The switching gate unit 40, the control gate unit 50, the start control unit 60, the end control unit 70, the active signal output unit 200, and the failure storage unit 210 are controlled by the sequence control unit 90 that controls the entire apparatus including them.

In the switching gate unit 40, when the input / output channels to be interconnected are designated, the WRIT from the sequence control unit 90 is specified.
Responsive to the clock signal of the E0 input, connecting both channels mutually. The connection between the specified channel and the unspecified channel is disconnected. In addition, the connection state at that time is retained for the channel not specified at this time.
As a result, a multi-channel connection that allows a communication path for a combination of a plurality of input / output channels at the same time in one node device 10 is performed.

The node device 10 has an active signal output unit 200,
This is a functional unit that generates an “active signal” indicating that the local node and its input / output channel are operating normally, that is, active. The active signal is not limited except for its signal length. The signal length is longer than the minimum time required to operate the flip-flop of the start control unit 60, and is set to such a length that it reaches and finishes within the “active detection time constant” described later.

The specific configuration of the start control unit 60 includes a first-arrival input signal detection unit and an input signal detection unit. The first-arrival input signal detection unit
It is a functional unit that identifies the first input signal among the input channels i0 to i3 according to the first-come-first-served logic. The arrival of the first forward signal is reported to the sequence controller 90. The input signal detection unit is a circuit that detects whether an input signal has arrived at the input port 20. The arrival of the first recovered signal is reported to the sequence controller 90.

The failure storage unit 210 is a storage circuit for storing a failure or dormant channel.

The termination control unit 70 includes a communication termination detection unit and a connection storage unit. The communication end detection unit has a circuit for detecting the end of communication based on a time based on a communication end detection time constant described later. The sequence control unit 90 is notified that there is communication that has ended among the communication with the fixed communication path, or that the first outgoing signal from the first-arrival input channel has been interrupted. The control gate unit 50 selects which information is to be reported. As can be seen, the termination control unit 70 identifies the termination of the communication when both of the two input channels included in the communication with the fixed communication path have no signal. The connection storage unit stores the channel for which the communication path has been fixed.

The end of communication is identified by the absence of a signal or the continuation of a predetermined logic state for a period of time according to the communication end detection time constant. The “communication end detection time constant” is a time for detecting that the communication has ended because no signal continues after the forward signal or the backward signal. Its length is
In the case of full-duplex communication, it is set to the time required to distinguish the end of true communication from the continuation of "0" or "1" which is the information content. Usually, some margin time is added to this. For example, 1 for Manchester coding
In the case of a coding rule in which “0” is inserted into “1” of 6 consecutive bits in NRZI, a time length of 7 bits or more is taken. Normally, they are set to twice as long, that is, a time length of 2 bits or 14 bits, respectively. This is the same as the input signal detection time constant.

When including half-duplex communication as well as full-duplex communication, the length of the communication end detection time constant is the propagation delay time that makes a round trip to the maximum effective network length, and after the terminal 14 finishes receiving the backward signal or the forward signal. It is set to be substantially equal to the sum of the time required to start transmitting the backward signal or the forward signal. This is the same as the terminal response monitoring time. Usually, some margin time is added to these.

With such a configuration, the communication end detection unit is always in a state of being able to detect the end of communication for all channels. That is, since the communication end can be detected also for the channel not selected by the control gate unit 50, there is no delay corresponding to the communication end detection time constant in detecting the communication end when switching is performed.

Further, in the case of full-duplex communication and in the case of including both full-duplex communication and half-duplex communication, the communication end detection time constant may be set according to each. Therefore, it is not necessary to change the hardware of the device itself. Also, the end control unit 70
May be configured to identify the end of communication when there is no signal on any of the two input channels included in the communication with the fixed communication path.

The sequence control unit 90 has a gate group for generating a control signal necessary for controlling the present apparatus, and a circuit for prioritizing the end of communication when the occurrence and end of communication conflict. The “active detection time constant” and the “input signal detection time constant” are formed by the sequence controller 90. The sequence control unit 90 also does not need to change the hardware of the device itself between the case of full-duplex communication and the case of including both full-duplex communication and half-duplex communication.

A false signal sending unit 30 is provided between the output port 30 and the input port 20.
0 is connected. In this embodiment, the false signal sending unit 300 is
It is connected between any one of the input channels i0 to i7 of the input port 20 of the node device 10 and the corresponding output channel. The pseudo signal sending unit 300 may be mounted on all channels included in the input port 20 and the output port 30, but may be selectively mounted on some of them. Further, it may not be mounted on all the node devices 10 in the system, and may be selectively mounted on a specific node device 10.

The fake signal sending unit 300, when the response signal from the receiving terminal does not arrive within a predetermined period after the arrival of the input signal from the input channel to which it is connected, generates the fake signal to the input channel. It is a circuit for setting up a link in the communication network. More specifically, when an input signal comes first from a specific one of the input channels i0 to i7 as described later, the signal is output to all output channels other than the first-arrival input channel by the switching gate unit 40. It Therefore, in this embodiment, the signal sending unit 300 monitors the signal output from the corresponding output channel of the output port 30, and when this output signal continues for a predetermined period, sends a false signal to the corresponding input channel of the input port 20. Has a function to output. The predetermined period will be described later in detail.

The node device 10 assumes a false signal input from the false signal transmitting unit 300 to the input channel as a response signal from the destination terminal to the earliest input signal, and performs a normal operation of setting a link for the corresponding channel. To do. This avoids abnormal conditions such as unnecessary network oscillation, continuous broadcasting, and inability to release the set link.

In the case of full-duplex communication, the above-mentioned predetermined period is a period starting from the detection of the first-arrival input channel of the first forward signal, and its length is the propagation delay time to and from the maximum network length. , Is set to be substantially equal to the sum of the time required for the receiving terminal to start transmitting the first backward signal after starting to receive the first forward signal. When including full-duplex communication and half-duplex communication, it is a period starting from the end of the first forward signal. The length is the sum of the propagation delay time that travels back and forth the maximum network length and the time required for the receiving terminal to finish transmitting the first forward signal and start transmitting the first backward signal. Set substantially equal. Usually, some margin time is added to these.

Referring to FIG. 2, an example of the configuration of the false signal sending unit 300 is illustrated. This example of configuration is a time constant setting circuit 302 for setting a time constant for sending the false signal, and detection for detecting the states of the output ports 30. A circuit 304 and a timer circuit 306 for monitoring the continuation of a particular state of the output port 30 are connected and configured as shown.

In this embodiment, the output channel of output port 30 is normally low in the idle state with no signal. Detection circuit
Reference numeral 304 denotes a circuit for distinguishing the low level of this idle state from the low level included in the output signal. In the present embodiment, when the low level of the output channel continues for 3 pulses of the clock CLOCK1, it is determined as the idle state. To do. Its QC output 308 is connected through inverter 310 to the clear input CLR of timer circuit 306.

The timer circuit 306 responds to a high-level signal input from the output channel to the detection circuit 304, and responds to this by inputting a clock
Start counting CLOCK1. In this embodiment, if the high level continues while counting 7 pulses, the timer circuit 306 sets its outputs QG and QH to the high level. This is output as a false signal to the input channel corresponding to this circuit via the timer circuit 306, the AND gate 314 and the switch SW. The switch SW is connected to the contact b when the false signal sending unit 300 is kept in the operating state. Flip flop 312
The false signal from the output 316 of the output 316 is thereby continuously output from the terminal 318 to the input channel. The continuous period of the false signal may be substantially the same as the communication end detection time constant described above. It is sufficient that at least one spurious signal pulse is generated within that period.

When the false signal sending unit 300 is made inoperative, the switch SW is connected to the contact a. In this case, the channel is used as a normal channel, that is, a channel without a false signal sending function. The contact a is connected to the connector of the device 10 and is connected to the terminal or node of that channel.

The time constant of the timer circuit 306 is set in the time constant setting circuit 302 by the data setting switch DSW. By setting the time constants for sending the false signal to different values between the channels, it is possible to give priority to the channels or the node devices 10. That is, since a channel for which a short time constant is set is input to a false signal input channel earlier than other channels, the channel is treated as a channel to which a response signal arrives first.

By the way, the output 316 of the flip-flop 312 and the QH output 350 of the timer circuit 306 are also used as a monitor output. The monitor O detects the presence of an input channel that outputs such a false signal, that is, an abnormal state such as network oscillation, continuation of broadcast, and inability to release the set link occurs, and a false signal is transmitted to establish a suspicious link. This is a terminal that displays the information as maintenance information outside the node device 10, for example.

The maintenance information is also output from the output 316 of the flip-flop 312 and the QH output 350 of the timer circuit 306 through the inverter 352 and the AND gate 354, and one input of the AND gate 320 provided corresponding to the channels 1 to n, and The maintenance information of monitors 1 to n is also output to the outside through the flip-flop 322. This information can be sent out of the communication network and used for network operation and maintenance. AND gate 3
The other input 324 of 20 is connected to the output from the start control unit 60, which is a signal branched from the start control unit 60 to the active signal output unit 200. The maintenance information of these monitors 1 to n displays the channels that output false signals in correspondence with the channels.

A reset switch RSW is connected to the reset terminals R of the flip-flops 312 and 322, respectively, and the flip-flop 322 set by sending a false signal can be reset by operating the switch RSW. In other words, the false signal sending unit 300 is configured to reset the reset switch RS even if there is no input signal from the monitored input channel.
Continue sending false signals until W is operated. Therefore, the link established in response to the false signal is not released until then. When the flip-flop 312 is reset, the signal becomes low level because it has been sent to the input channel, and the monitor O is deactivated. Similarly, when flip-flop 322 is reset, the corresponding display on monitors 1-n is deactivated.

When the output QG of the timer circuit 306 becomes high level, a false signal is sent out. At this time, a signal is branched and input from the start control unit 60 to the set input S of the flip-flop 322. That is, among the inputs of those flip-flops 322, only the one corresponding to the first-arrival input channel is at the high level, and therefore the flip-flop is set. When the QH output 350 of the timer circuit 306 goes high, the S inputs of all flip-flops 322 go low, and these flip-flops 322 are no longer set. These flip-flops 322 are switches R
It is initialized when the SW is operated.

The circuit example of the false signal sending unit 300 shown in FIG. 2 continuously sends false signals. However, the spurious signal may be a single pulse. FIG. 3 shows an example of a circuit of the false signal generating unit 300 which generates a single pulse false signal. Node device 1
0 sets the link when a single false signal pulse is input as the first recovery signal from the input channel, but since there is no recovery signal thereafter, the link is released with the disappearance of the forward signal.

In the circuit example of FIG. 3, the QH and QG outputs of the timer circuit 306 are connected to the b terminal of the switch SW and one input of the AND gate 320 via the inverter 330 and the AND gate 332. The AND gate 320 is a three-input gate, and the branch signal from the start control unit 60 to the active signal output unit 200 is connected to the other one input. A data signal is input to the input channel of the input port 20. The remaining one input 356 is commonly connected to the output of the inverter 330. The QG output of timer circuit 306 is also commonly connected through inverter 358 to the reset input R of flip-flop 322.

As a result, the false signal sending unit 300 sends a single false signal pulse to the input channel by the detection circuit 304 and the timer circuit 306 when the output channel outputs the signal for the predetermined period. In response to this, the node device 10 sets a link. The node device 10 releases the link as soon as this outgoing information disappears. Similarly, the set terminal S of the monitor flip-flop 322 also outputs the output QG of the timer circuit 306.
Is high and the output QH is low, only the one corresponding to the first-arrival input channel is energized high. After that, when the output QH of the timer circuit 306 becomes high level, the set terminals S of all the flip-flops 322 become low level, and thereafter, these flip-flops 322 are not set. When the signal from the output port 30 disappears and the timer circuit 306 is cleared, the reset terminal R of the flip-flop 322 becomes high level, and all the flip-flops 322 are reset.

By the way, the communication network monitoring device 700 may have a configuration similar to that of the false signal transmitting unit 300. An example thereof is shown in FIG. This configuration example has a function of generating a discontinuous signal such as a single pulse as a false signal and releasing the link as soon as there is no input signal from the transmission line 12. Its composition is
As can be seen from the figure, the false signal sending circuit shown in FIG.
The configuration may be similar to the AND gate 332 of 300. Therefore, in this figure, elements similar to those shown in FIG. 3 are designated by the same reference numerals.

The input unit 702, which is connected to the clear input CLR of the flip-flop 304 via an inverter, is connected to the reception line of the transmission line 12 from the node device 110, and the input signal arrived at this is received. Further, the output unit 704 connected to the output of the AND gate 332 is connected to the transmission line of the transmission line 12 from the same node device 10, and thereby the output signal is transmitted. The communication network monitoring device 700 shown in FIG. 4 monitors the signal received by the input unit 702, and when the signal continues for a predetermined length of time, outputs a false signal from the output unit 704 to the transmission line 12. To establish a link in the communication network. This link will be released as soon as there is no input signal.

The configuration example of the communication network monitoring device 700 shown in FIG. 5 has a function of releasing a link when a continuous signal is generated as a false signal, an input signal from the transmission line 12 disappears, and the switch RSW is operated. Is. As can be seen from the figure, its configuration may be the same as the configuration up to the AND gate 314 of the false signal sending circuit 300 shown in FIG. In the figure, the second
Elements similar to those shown in Figures and 4 are designated with the same reference numerals. The transmission line 1 from the node device 10 via the inverter to the clear input CLR of the flip-flop 304
The input signal is received from the second receiving line. Also, AND gate
The output unit 704 connected to the output of 314 is the same node device 10
The output signal is transmitted to the transmission line of the transmission line 12 from.

An outline of communication control in the node device 10 will be described. Here, for convenience, the term “transmission terminal” refers to a terminal that sends a signal to the transmission line 12, and “reception terminal” refers to a signal that is transmitted to the transmission line 12.
It means the terminal on the receiving side from 12. Also, the term "originating terminal" refers to a terminal in which a connection is not set up with another terminal, that is, a terminal that starts transmitting information addressed to a specific terminal from an idle state, and the "receiving terminal" is the terminating terminal. A destination terminal that returns a response to information for the first time.
A signal transmitted from the transmitting terminal is called an "outgoing signal", and a signal transmitted from the receiving terminal, particularly a signal returned in response to the outgoing signal, is called a "return signal".

In a certain node device 10, in an idle state in which a connection is not set between specific input / output channels, the connection gate of the switching gate unit 40 is in an open state, and all input channels exclude output channels corresponding to each. Connected to all output channels.

When an input signal arrives at any one of the input channels i0 to i7 in the idle state, the first-arrival input signal detector of the start controller 60 causes the earliest input signal among the input channels i0 to i7, that is, The "first come, first served channel" is detected by first come first serve logic. Broadcast is performed in which the signal received from the first-arrival input channel is transferred to all output channels except the corresponding output channel.

The sequence control unit 90 is activated by detection of the first-arrival input channel of the first-arrival input signal unit of the start control unit 60, and the sequence control unit 90 starts time monitoring by the active detection time constant.

The "active detection time constant" is the time when the first or first outgoing signal from the same transmission source is received from an input channel other than the input channel that first detected the input signal, or from another transmission source. It is a time for receiving another first forward signal or receiving an active signal.

The length of the active detection time constant is set to be substantially equal to the sum of the propagation delay time that travels the maximum allowable distance between the adjacent node devices 10 or the terminals 14 and the time required for the active signal. Usually, some margin time is added to this. Within this time, the first diverted from the same source
The second forward signal, another first forward signal from another transmission source, or the active signal arrives. This makes it possible to detect a faulty or dormant channel.

The channel in which the input signal arrives within the monitoring time limit of the active detection time constant is stored in the flip-flop of the input signal detection unit of the start control unit 60. When the period defined by the active detection time constant has expired, the sequence control unit 90 clocks the failure storage unit 210 to input the input channel i0.
The input channel in which the input signal does not arrive within the period of the active detection time constant among i3 to i3 is stored in the flip-flop 212 as a fault or a dormant channel.

Then, the sequence controller 90 monitors the time constant of the input signal detection time constant. The “input signal detection time constant” is the time for detecting whether or not there is a signal after the elapse of the period according to the active detection time constant. Its length is, for example, 1 bit for Manchester coding, 6 consecutive in KRZI.
7 if the encoding side inserts "0" into the bit "1"
It takes a bit longer than a bit. Usually, some margin time is added to this, and it is set to twice as long, that is, a time length of 2 bits or 14 bits, respectively. This is not the input channel that detected the input signal first, but the first forward signal from the same transmission source or another first transmission signal from another transmission source.
It is the time for detecting the input channel that has received the second forward signal by distinguishing it from the active signal.

The channel in which the input signal arrives within the monitoring time limit of the input signal detection time constant is stored in the flip-flop of the input signal detection unit of the start control unit 60. At the end of this period,
The switching gate unit 40, when an input signal subsequently arrives from any of the input channels for which there is no input signal within the period of the input signal detection time constant stored in the input signal detection unit, first input that input channel. Connect to the output channel that corresponds to the channel.

When there is no input signal in any of the input channels included in the communication path and the termination control unit 70 has passed the time defined by the communication termination detection time constant, the sequence control unit 90
The sequence controller 90 resets the first-arrival input signal detector of the start controller 60 and the input signal detector of the start controller 60 to the initial state.

The end of the communication may be detected by monitoring an input signal from the first-arrived input channel, detecting that the input signal has disappeared, and performing a recovery process. The input signal from both of the other input channels may be monitored to detect that either of them has disappeared, and to perform a recovery process. The detection of the disappearance of the input signal is performed when the logic state of the signal is in a predetermined state for the period of the communication end detection time constant.
For example, it is performed by detecting that it is maintained at "0".

In the above-described embodiment, the input signal is received during the period according to the active detection time constant, and the input channel for which the input signal is not received during the period according to the input signal detection time constant is stored in the input signal detection unit 60b even after the passage. , Only the input signals of those input channels can be detected. Configured to connect an input channel that did not receive such an input signal to the output channel corresponding to the first-arrival input channel and disconnect all other input channels from the output channel after the synchronization period has elapsed. You may.

When the first recovered signal arrives after the lapse of the input signal detection time constant in the input channel in which such an input signal has not arrived, the input channel that has received the first recovered signal becomes the first-arrival input channel. Connect the first-arrival input channel to the corresponding output channel, and connect the first-arrival input channel to the output channel corresponding to the first input signal from which the recovered signal arrives, fix the path between the input and output channels, and input all other input channels to that input. Connect to all output channels except the output channel corresponding to the channel.

In order to understand this embodiment, a communication procedure in the system of this embodiment will be described with reference to FIGS. 6A to 6E regarding a grid communication network in which four node devices 10 are connected in a grid.
In this illustrative communication network, four node devices 10a-10d are connected by a transmission line 12 in a grid pattern. Node device
Terminals 14a and 14d are connected to 10a and 10d, respectively. In the figure, the hatched side indicates the transmitting side, and the thick line indicates the flow of information signals.

For full-duplex communication, detection of an input signal and connection control between input / output channels based on the detection are performed in the following seven basic steps.

First, as shown in FIG. 6A, in the first step, a calling terminal that wants to send data for the first time from an idle state, for example,
14a sends the first forward signal in the form of a packet to the node device 10a through the transmission line 12a. The first outgoing signal includes a destination address indicating a destination terminal, for example, 14d. The node device 10a detects the first forward signal as the first-arrival input signal. That is, the channel on which the input signal arrived first, that is, the “first-come-first-served input channel” is identified by the first-come-first-served logic. So the first-arrival input channel
All output channels 12ab except the output channel corresponding to 12a
And the first outgoing signal to 12ac or the like. That is, the first outgoing signal is broadcast to all routes of the node device 10a.

When the node device 10oa further receives the first outgoing signal on the first-arrival input channel, the node device 10oa disconnects all other input channels whose communication paths are not fixed to the output channels, and causes the active signal output unit 200 to Active signal 230a from output channel corresponding to first-arrival input channel
Is output.

Next, in the second step, as shown in FIG. 6B, the other node devices 10b, 10c, and 10d also have their respective transmission paths 12ab,
This first forward signal is received from 12ac and 12bd and 12cd, and the same broadcast is performed. In this example,
The node device 10c recognizes the transmission path 12ac as the first-arrival input channel and broadcasts it to another transmission path such as the transmission path 12cd. Similarly, the node device 10d is the same as the node device 10d in addition to the transmission line 12bd.
The first outbound signal arrives from 2cd, but the transmission line 12bd
Is recognized as the first-arrival input channel, and only the first forward signal from the transmission line 12bd is broadcast to other transmission lines such as the transmission lines 12d and 12cd, and the signal from the transmission line 12cd is not output. In the node devices 10c and 10d, if the arrival time difference between the first-arrival input signal and another input signal that arrives later than that is shorter than the time required for connection control, duplication occurs for a moment.
However, since this occurs in the preamble part of the message packet, there is no problem. In this way, the terminal
The first outbound signal transmitted from 14a and broadcast from node 12 is conveyed in the network without duplication. Thus, the first outgoing signal via the shortest path reaches the terminal 14d.

The node devices 10a to 10d monitor all the input channels within the period of the active detection time constant starting from the detection of the first-arrival input channel, and identify the input channel that has not received the input signal within the period. They are stored in the input signal detector 60b. In each node device 10, if the input channel, the output channel, and other node devices or terminals connected to the node device are functioning normally, the active signal or the first signal is sent within the period of the active detection time constant. The outbound signal should arrive. For example, the node device 10
If a signal is not received by the input port 234bx at b for some reason, this is stored in the node device 10b.

The node devices 10a to 10b detect an input channel for which there is no input signal within the period according to the input signal detection time constant that starts after the active detection time constant has elapsed. At this time, the active signal has already ended. At this time, the node devices 10a to 10d may be configured to connect the detected input channel to all output channels other than the corresponding output channel. Furthermore, the node devices 10a to 1
0d is an input channel that is not stored in the input signal detection unit 60b among the detected input channels, that is, an input channel in which a signal arrives within the period of the active detection time constant, and all outputs other than the corresponding output channels. It may be configured to connect to a channel.

In the third step, the terminal 14 connected to the node devices 10a to 10d receives the first outgoing signal. At that time, each terminal 14 sends back the active signal 232, and
The destination address included in the second outbound signal is compared with the own address. In this example, the terminal 14d sends the active signal 232d, and since the destination address matches that of its own station, the terminal 14d sends the first or first recovery signal to the transmission line 12d. As shown in FIG. 6C, the node device 1
0d is the input channel that does not arrive within the period defined by the input signal detection time constant among the input channels corresponding to the output channel that sent the first forward signal, and is defined by the input signal detection time constant. The input channel from which the signal arrived after the end of the period. It is connected to the output channel corresponding to the first-arrival input channel.

In this example, as shown in FIG. 6C, the node device 10d
After the period according to the input signal detection time constant elapses, the transmission line 12
When the signal is received from d, the input channel that receives the signal, that is, the first recovered signal is connected to the output channel 12bd corresponding to the first-arrival input channel. Therefore, the first recovered signal received from the transmission line 12d is the node device 1
It is transmitted from 0d to the transmission line 12bd.

Then usually the terminal response monitoring time or full duplex communication,
After the time corresponding to the communication end detection time constant when half-duplex communication is included, all other input channels are connected to all output channels except the output channel corresponding to that input channel. This can prevent the node device 10d from detecting the first forward signal of the transmission line 12cd in FIG. 10C. That is, in this example, this results in transmission line 12
bd and 12d are mutually connected.

In the fourth step, the node devices 10b and 10a also perform the same control as the node device 10d. Therefore, as shown in FIG. 6D, the first backward signal reaches the transmitting terminal 14a by following the path to which the first forward signal is transferred in the reverse direction.
The first forward signal has a certain length, and the terminal 14
Since the terminal device such as d is configured to transmit the first backward signal as soon as the destination address of the first forward signal is identified, the first backward signal is the first forward signal. It is transmitted while overlapping. Therefore, terminal 14a
Even if other terminals than 14d and 14d are connected to this network, they cannot participate in this communication. As a result, confidentiality is maintained for communication with other terminals, which is important for the communication system, and multi-channel communication is enabled.

As shown in FIG. 6E, in the fifth step, the node device 10c does not receive the first recovered signal from the transmission line 12cd and the first forward signal received up to that time on the transmission line 12ac. When it disappears, it detects this and connects all input channels to all output channels except the output channel corresponding to that input channel. That is, when it is detected that the input signal is not received during the period of the input signal detection time constant, the first backward signal does not arrive after that time, and the first forward signal is not received. , Connect all input channels to all output channels except the output channel corresponding to that input channel. This means that the communication is not routed through the node device 10 and the route is fixed, or the communication is not established and the transmitting terminal has stopped the transmission of the first forward signal. Therefore, in other cases, the arrival of the first recovered signal is guaranteed within the terminal response monitoring time starting from the detection of the first-arrival input channel. When the sending terminal 14a interrupts the return of the first forward signal on the way because the first forward signal does not reach the receiving terminal 14d for some reason and therefore the first backward signal is not returned. Is also the same.

When both the full-duplex communication and the half-duplex communication are included, the node device 10c does not receive the first forward signal, and thereafter, even if the period due to the communication end detection time constant elapses, the first return signal is returned. When it detects that no signal arrives, it detects this and connects all input channels to all output channels except the output channel corresponding to that input channel. That is, if it is detected that the first reverse signal is not received within the terminal response monitoring time that starts from the end of the first forward signal, it is detected that all input channels have not received any input signal. Connect the channel to all output channels except the output channel corresponding to that input channel.

By such connection control, the sending terminal 14a and the receiving terminal 1
One communication path is set and fixed for communication with 4d. Each node device 10 can control the setting of communication that newly occurs with respect to a path that is not fixed.

In this way, each node device 10 detects the presence or absence of an input signal and performs sequential control regarding the active detection time constant, the input signal detection time constant, the terminal response monitoring time, and the communication end detection time constant. The same applies to the control regarding the end of communication. For example, in the case of giving permission to continue and terminate communication to one calling terminal in full-duplex communication, that is,
Normally, when the first forward signal is continuous at an interval shorter than the signal end detection time and the backward signal is transmitted intermittently,
All the inputs are detected by detecting that the first forward signal has disappeared for a pair of input channels for which the communication path has been fixed, and that there has been no input signal on any of the input channel pairs. Connect the channel to all output channels except the output channel corresponding to that input channel.
Naturally, this return signal is not transmitted.

In the case of half-duplex communication, or in the case of full-duplex communication where there is no need to set the priority for the transmitting station and the receiving station, there is no input signal on both of the pair of input channels that have the fixed path. Then, all input channels are connected to all output channels except the output channel corresponding to the input channel.

By the way, the false signal generating unit 300 does not have to be installed in all the node devices 10 in the network. Further, it is not necessary to be mounted on all the channels accommodated in a certain node device 10, and may be mounted in one or more node devices 10, and a certain node device to which the false signal generating unit 300 is connected. After the input signal arrives at a certain input channel of 10, if the response signal from the receiving terminal does not arrive at another input channel of the node device 10 before the above-described predetermined period has elapsed,
Therefore, the signal generator 300 generates a signal for the input channel to which it is connected.

More specifically, when an input signal comes first from a specific input channel, the outgoing signal is output to all output channels other than the first-arrival input channel. Therefore, the signal sending unit 300
Monitoring the signal output from the output channel. For example, if the network oscillates or the broadcast state continues due to transmission to a non-existent destination,
The signal transmission state of this output channel is monitored by the signal transmission unit 300, and if this continues for a predetermined period, the false signal transmission unit
300 outputs a false signal to the input channel. In response to this false signal, the node device 10 establishes a link between those input / output channels. The operation is the same as the normal operation described above.

More specifically, each node device 10 artificially pretends as a response signal from the destination terminal to the earliest input signal, the pseudo signal arriving at each input channel from the false signal transmission unit 300, and regarding the corresponding channel. Performs the normal operation of setting a link. As a result, a link is set up in the communication network, and an abnormal state in which the entire network is occupied by continuation of broadcasting is avoided.

In the circuit example of the false signal sending unit 300 shown in FIG. 2, false signals are continuously sent. The occurrence of this abnormal state is displayed outside the node device 10 as the maintenance information of the monitor O. The input channel is displayed on any of the monitors 1-n.
The maintenance person can operate the reset switch RSW corresponding to the input channel to cancel the false signal transmission state. Until this reset operation, the false signal sending unit 300 continues to generate a false signal on the input channel.

In the circuit example shown in FIG. 3, the false signal is sent in a single pulse form. As a result, the node device 10 sets the link and releases the link when the input signal disappears.

The communication network monitoring device 700 monitors the input signal arriving at the input unit 702 from the receiving line of the transmission line 12 from the node device 10, and when the first outgoing signal continues for a predetermined time or longer, restores the false signal. Is transmitted from the output unit 704 to the transmission line 12, thereby establishing a link in the communication network. The false signal is transmitted as a non-continuous signal, for example, a single pulse in the communication network monitoring device 700 shown in FIG. 4, and the device 700 shown in FIG.
Is transmitted as a continuous signal. The once established link is released in the device 700 shown in FIG. 4 as soon as there is no input signal from the transmission line 12, and the device 70 shown in FIG.
At 0, there is no input signal from the transmission line 12, and when the switch RSW is operated, it is released.

The information signal transmitted through the transmission line 12 is in the form of a message packet in this embodiment. As shown in FIG.
The message packet 100 as the second forward signal includes at least the preamble P and the destination address D prior to the message M. The preamble P needs to last at least a predetermined length. This is the terminal
It is for synchronization of 14. Although there is no other restriction on the packet 100, it normally has the address of the oscillation terminal 14, that is, the source address S. The message M may be followed by a check code area such as CRC and a packet end code E, followed by a postamble for maintaining synchronization of the terminals.

Upon detecting the reception of the first forward signal, the terminal 14 immediately outputs an active signal.

If the first outgoing signal is received and it is determined that the destination address of the packet is addressed to the own station, the terminal 14
Is the response signal immediately after the determination in the case of a full-duplex communication terminal (Fig. 8) and immediately after the end of the first forward signal in the case of a half-duplex communication terminal (Fig. 10). , The first recovery signal is transmitted. Although there is no restriction on the first return signal, the response packet 10 as the first return signal
2 usually has the same format as the first forward signal as shown in FIG. 8 or FIG.
It has a destination address D and the address of the terminating terminal 14, ie the source address S, followed by a code indicating an acknowledgment ACK or a negative acknowledgment NACK. This may be followed by message M. When full full-duplex communication function such as voice communication and video communication such as videophone is required, response packet 10
2, a message M is also added. As mentioned above, the first
It is assured that the second recovery signal is preferentially transmitted to the calling terminal.

The transmitting terminal 14 monitors the reception of the first recovery signal transmitted from the receiving terminal within the "terminal response monitoring time" of a predetermined length. If the reception of the first return signal is detected within the terminal response monitoring time, it is determined that the receiving terminal is in a state where it can respond normally, and communication can be continued.

The transmitting terminal stops transmission when there is no input signal within the period of the active detection time constant after starting the transmission of the first forward signal or when there is an input signal within the period of the input signal detection time constant. To do. In the former case, it means that there is a failure in the transmission line or node device to which the terminal is connected, and the repair is necessary. In the latter case, it means that a collision has occurred with the node device to which the terminal is connected, and the transmitting terminal shifts to the retransmission processing of the first forward signal.

When the reception of the first backward signal is not detected within the terminal response monitoring time, it is judged that the first forward signal did not reach the called terminal or the called terminal was not in a state where it can respond normally. Then, the oscillating terminal suspends communication as shown in FIG. The oscillator terminal 14 can then retransmit the first forward signal. This may be the same control as in the CSMA system, for example. With these functions, the path between the calling and called terminals is fixed, and communication can be performed while occupying the communication channel.

For terminals with full-duplex communication, the "terminal response monitoring time"
This is the time starting from the time when the transmitting terminal starts transmitting the first forward signal. The length is substantially equal to the sum of the propagation delay time to and from the maximum effective network length and the time required for the receiving terminal to start transmitting the first backward signal after receiving the first forward signal. Are set equal to each other. Usually, some margin time is added to this.

In the case of a system that includes both full-duplex communication and half-duplex communication, the “terminal response monitoring time” is a time that starts from when the transmitting terminal has finished transmitting the first outgoing signal. The length is the sum of the propagation delay time for reciprocating the maximum effective network length and the time required for the called terminal to start transmitting the first return signal after finishing receiving the first outgoing signal. Is set substantially equal to Usually, some margin time is also added to this. Node device within terminal response monitoring time
It is guaranteed that the input signal reaches 10.

The receiving terminal may notify the transmitting terminal of the completion after receiving the first outgoing signal correctly. That is, this is realized by transmitting the first return signal immediately after the reception of the first forward signal is completed. This includes an acknowledgment ACK or a negative acknowledgment NACK.

When transmitting the forward signal or the backward signal following the first forward signal or the first backward signal, that is, when transmitting a plurality of packets continuously, the terminal 14 determines the communication interval between the packets. It is sufficient that the time does not exceed the time specified by the end detection time constant. In other words, when communication is continued, that is, when the set communication path is used in a fixed manner, the next time the packet specified by the communication end detection time constant elapses after the end of the packet being transmitted. May be transmitted.

For example, in the case of full-duplex communication, a dummy signal such as a postamble is inserted between successive packets, that is, between the Nth packet and the (N + 1) th packet so that the communication end detection time constant does not time up. To If half-duplex communication is involved, when the packet being received ends,
The transmission packet is transmitted before the communication end detection time has elapsed. In other words, when the receiving terminal finishes receiving the N-th outgoing signal, within a time period defined by the communication end detection time constant,
Preferably, immediately after transmitting the N-th recovery signal, the oscillating terminal, when finishing receiving the N-th recovery signal, also preferably immediately, within the time defined by the communication end detection time constant, the (N + 1) th recovery signal. Send outbound signal. For example, in the case where the packet system is not adopted in voice or video communication, the no-signal state may be set shorter than the communication end detection time constant.

 To end the communication, the terminal may stop transmission.

As long as the restrictions on these communication procedures are followed, the degree of freedom with respect to other points is high, and the following effects can be obtained. First, there is no limit on the maximum and minimum packet lengths, and the packet format does not have to be taken. Next, the number of continuous repetitions of the forward information and the return information is not limited, and the communication channel may be occupied. In addition, if the data rate is less than the maximum data rate determined by the hardware configuring the network, the data rate can be freely determined between the transmitting and receiving terminals. Fourth, full-duplex communication and half-duplex communication can be freely selected and may be mixed.

In summary, in this practical example, one node device 10 realizes multi-channel communication that allows a plurality of communications at the same time. The high fault tolerance of the grid communication network that forms links by first-come-first-served logic while avoiding failed nodes and failed lines is maintained.

Further, the false signal generating unit 300 connected to a certain channel of the node device 10 is, after the input signal arrives at the input channel,
If the response signal from the receiving terminal does not arrive at another input channel of the node device 10 before the elapse of a predetermined period, a false signal is generated in the input channel. Each node device 10 assumes this false signal as a response signal from the destination terminal to the earliest input signal, and performs a normal operation of setting a link for the corresponding channel. Thereby, a link is set up in the communication network, and an abnormal state in which the entire network is occupied by the continuation of the broadcast state due to the oscillation of the node or the terminal or the transmission to the nonexistent destination is avoided.

Further, the communication network monitoring device 700 is arranged at a position corresponding to the terminal 14, monitors the input signal from the transmission line 12, and when the first outgoing signal continues for a predetermined time or longer, the false signal is regarded as a return signal. It is sent to the transmission line 12 and a link is set up in the communication network. As a result, it is possible to avoid the abnormal state.

Effect According to the present invention, by providing a function for generating a false signal at a position corresponding to a port and / or a terminal of a node as described above, the node or the terminal oscillates or broadcasts by transmission to a nonexistent destination. Even if the state continues, one port or terminal-equivalent device sacrifices to set up a link, which minimizes the effect on accepting other new communication and releasing the already set link. Be converted. That is, there is provided a node device and a communication network monitoring device for an irregular communication network in which continuation of an abnormal broadcast state is avoided. This function may be provided in a plurality of ports and / or terminals, and it is possible to monitor the occurrence of an abnormal state at a plurality of ports or positions corresponding to the terminals.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing an embodiment of a node device of an irregular communication network according to the present invention, and FIGS. 2 and 3 are circuit diagrams showing a specific circuit configuration example of a false signal generating unit in the node device. , FIG. 4 and FIG. 5 are circuit diagrams showing a specific circuit configuration example of the communication network monitoring device, and FIGS. 6A to 6E are the node device shown in FIG. FIG. 7 is a relay system diagram showing an example of a communication network configuration in which the same node device is applied to a grid communication network, and FIG. FIG. 9 is a diagram showing a packet flow in the case where the first backward signal is normally returned in response to the first forward signal in the duplex communication, and FIG. 9 shows the first forward signal in the full-duplex communication. Packet when the first return signal that responds to the signal is not returned normally 10 is a diagram showing the flow of packets, and FIG. 10 is a diagram showing a packet flow when the first backward signal is normally returned in response to the first forward signal in half-duplex communication. It is a figure similar to. Explanation of symbols of main parts 10 …… Node device 40 …… Switching gate unit 50 …… Control gate unit 60 …… Start control unit 70 …… End control unit 80 …… Gate set bus 90 …… Sequence control unit 200 …… Active signal output unit 210 …… Fault storage unit 300 …… Fake signal sending unit 700 …… Communication network monitoring device i0 to i7 …… Input channel o0 to o7 …… Output channel

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-57-104339 (JP, A) JP-A-58-139543 (JP, A) JP-A-63-74240 (JP, A) JP-A-63- 74241 (JP, A) JP 63-74347 (JP, A) JP 63-74348 (JP, A) JP 63-74349 (JP, A) JP 63-212241 (JP, A) JP-A-63-276940 (JP, A)

Claims (2)

(57) [Claims] 1. A node device connected to a transmission line including a transmission line to a terminal or a node device and a reception line corresponding to the transmission line, and at least one input means to which the reception line is connected, respectively. At least one output means to which the transmission line is respectively connected, a connecting means for connecting the input means and the output means, and a connection means for controlling the connecting means to selectively connect the input means to the output means. In a node device of an irregular communication network having a control means, the control means controls the connection means when the input means that receives a forward signal to the terminal comes first among the input means, Transferring the outgoing signal from the identified input means to all output means other than the output means corresponding to the identified input means, wherein the control means includes the identified input of the input means. means If there is an input means that receives the return signal from the terminal other than the above, the connecting means is controlled so that the input means that receives the return signal corresponds to the input means that receives the forward signal first. In addition, the input means that receives the forward signal at the earliest is connected to the output means corresponding to the input means that receives the restored signal at the earliest to fix the connection between the input and output means, and the device is Further, it includes a false signal sending means for monitoring at least one of the output means and sending a false signal to any of the input means when the output means continues to send the forward signal for a predetermined period or longer. A node device of a characteristic amorphous network. 2. A multi-input / single-output node device is connected to a multi-coupling structure, wherein the node device transfers an input signal to an output by a first-come-first-served logic. In a network monitoring device of an irregular communication network connected to a transmission line including a reception line corresponding to a line, an input unit connected to the reception line, an output unit connected to the transmission line, and the input unit A forward signal that arrives at the output signal, and when the forward signal continues for a predetermined length of time, the output means outputs a false signal as a return signal. Network monitoring equipment for fixed-form communication networks.