JPH0528932B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a ring link type switching system, in particular, to a ring-link type switching system, in particular, a plurality of terminal equipment for accommodating and connecting communication lines are connected in series in a skewer shape to provide a predetermined packet switching service. The present invention relates to a ring link type switching system having at least one ring link for unidirectionally transmitting communication information including data/signals.

[Background of the invention]

The circular link type switching system has a circular link in which a plurality of end station devices that accommodate and connect communication lines connecting communication terminal equipment and other exchanges are connected in series with high-speed transmission lines as links, and the exchange receives Communication lines are interconnected via a circular link using the received destination information.

First, the configuration of the annular link type exchange system will be explained with reference to FIG.

FIG. 2 is a relay system diagram showing an example of a circular link type exchange system. In FIG. 2, the exchange 21 has an annular link formed by a terminal device 211 and a link 212 connecting the terminal device 211 in series on a skewer. The switching function is controlled by applying a packet switching service procedure possessed by each terminal device 211. A communication line 22 is connected to each terminal device 211, and the communication terminal device 23 and other devices are connected via the communication line 22. It is connected to the exchange 24.

In recent years, optical fibers have been used to transmit information at higher speeds and in larger quantities, and by forming circular links with high-speed optical fiber transmission lines, large-capacity switching systems are becoming possible. On the other hand, in addition to telephone lines, dedicated lines for data and images are increasingly being used as communication lines, but increasing the capacity of transmission lines is a method of transmitting voice, data, images, etc. other than telephone calls as communication information on a single communication line. is being put into practical use.

As a switching system, the above-mentioned simple circular link type has been proposed by the same applicant as "Time Division Relay Switching System" in Japanese Patent Application No. 59-245320. This proposal applies a packet switching service on a ring link so that each terminal device accommodating a communication line has a communication information connection function, and further simplifies the control of communication information transferred on a ring link. This is one implementation means in which a terminal device can transmit communication information on a circular link only while holding a transmission permit (token).

In the token system using packet exchange services on a circular link, the communication information to be transferred includes a control frame and an information frame, and the control frame includes a token frame. In addition, the information frame contains the originating address (SA) as the terminal equipment code of the originating party.
and the terminating address (DA) as the terminal equipment code of the terminating destination.

[Conventional technology]

Conventional circular link type exchange methods include a method in which a central control unit is installed in the circular link to centrally control the circular link, a method in which only one transmission permit (hereinafter referred to as a token) is provided on the circular link, and a method in which multiple tokens are installed. Consideration is being given to adopting a method of deployment.

When the speed of the circular link increases and the amount of information to be handled and processed increases, a large central control unit or a plurality of complex central control units will be put into practical use. On the other hand, in the case of the token method, multiple terminal devices that form a circular link send out transmission information that has been stored and held only while holding the token, so when the amount of call processing increases, one token can go around the circular link. Time increases. Furthermore, when a plurality of tokens are deployed, the tokens are concentrated in one place, resulting in the so-called dumping phenomenon, so in order to avoid this phenomenon, a complex token control device is required to centrally control all the terminal devices.

[Problem that the invention seeks to solve]

In this way, the conventional ring-link type switching system is not economical or efficient because the central control unit becomes larger and more complex as the speed of the ring link increases and the number of terminal equipment increases. It lacks flexibility, and when one token is used, the time it takes for the token to go around the circular link and return increases, so information sent from the accommodated communication terminal device to other terminal devices accumulates, making it difficult to record the sent information. In addition to requiring an increase in area, there are many opportunities for a vicious cycle to occur in which the token round trip time increases due to the increase in retained information, causing problems in the exchange function.In addition, when using multiple tokens, it is necessary to avoid the so-called Dango phenomenon. Each of these had the problem of requiring a complex token control device to centrally control all terminal equipment.

[Means for solving problems]

The circular link type exchange system according to the present invention deploys a plurality of tokens on a circular link that forms a transmission path using a packet switching service, and when the end station forming the circular link starts holding tokens, the tokens are received by the end of the process. Accumulated transmission information to other terminal equipment is sent to the terminal equipment at the farthest position (adjacent) in the communication information transmission direction of the circular link. In order to send out information arriving at The token frame received from the device is inserted next to the one information frame being sent and sent. Furthermore, while the token is not held, communication information between other terminal devices is transferred as relay information to the subsequent device.

Therefore, the terminal device has two storage areas, a transmission control means that extracts and transmits the transmission information for each destination terminal device from the storage area, and receives information from the link as reception information, relay information, and relay information. The information transfer controller includes an information transfer control unit that classifies and transfers the waiting information and also sends out the token as the sending information next to the sending information.

The storage areas on the two sides switch states between storage and transmission when a token is received to start holding the token. In terms of the storage status, communication information starts to be stored at the start of token holding when there is no stored information, and communication information is received between the time when the storage ends at the start of the next token holding, and when communication information is received while the token is being held. Relay standby information is sequentially stored as transmission information with a key code assigned to each destination station device. On the other hand, in terms of transmission status, transmission of communication information is started at the start of token holding when there is accumulated information (transmission information), and all of the transmission information is sequentially transmitted.

〔Example〕

Next, the annular link type exchange system of the present invention will be explained by way of an embodiment with reference to the drawings.

FIG. 3 is a functional block diagram showing an embodiment of the terminal equipment according to the present invention. The end station device includes a communication information receiving unit 31 that receives communication information from the front end through a link in the form of an information frame as received information by the packet switching service, and determines the location of the destination end station device of the communication information from the received information frame. A reception information identification unit 32 that identifies the destination address (hereinafter referred to as DA) and the transmission permit (hereinafter referred to as token or TK), and the output received by the own terminal device and transmitted to other devices via the communication line. an acceptance information storage unit 33 that temporarily stores acceptance information as information; a communication line interface unit 34 that matches interconnection conditions with other devices via a communication line; a transmission information storage section 35 that stores and stores the received information and relay waiting information received via the communication information reception section 31 for transmission waiting;
A transmission frame forming unit 36 that forms transmission information into an information frame according to the packet switching service procedure.
, a communication information transmitter 37 that sends the communication information to the next device via a link, and a communication information transmitter 37 that sends the communication information to the next device via a link, and a communication information transmitter 37 that converts the received information into acceptance information, relay information,
and an information transfer control unit 38 that classifies relay standby information and sends out sending information and tokens as sending information.

The received information identification unit 32 determines whether the received frame is a token (TK) frame or not a token (hereinafter referred to as
The NTK) information frame has a control section identifying means 321 for identifying from the control section of the received frame, and a DA section identifying means 322 for identifying from the DA section of the NTK information frame whether it is the own DA or another DA.

The transmission information storage section 35 has two storage areas, an A storage area 351 and a B storage area 352, and a transmission control means 350. One side is transmitting stored transmission information, and the other side is used for input information. and relay standby information.

The transmission frame forming section 36 includes the transmission information storage section 3
The information frame forming means 361 forms the transmission information input from 5 into a predetermined information frame, and the token frame forming means 362 forms the token into a frame.

The information transfer control unit 38 is a token holding unit 38
1, and has an acceptance information gate 382, a relay information gate 383, a relay waiting information gate 384, a sending information gate 385, and a token gate 386, and receives the signal of the own DA, other DA, or TK from the reception information identification unit 32, As a result of transmitting and receiving a "transmission command/confirmation" signal with the transmission information storage section 35,
Receive “end of transmission”. The operation timing of each gate will be explained with reference to FIG.

First, details of the transmission information storage section 35 shown in FIG. 3 will be explained with reference to FIG. 4. FIG. 4 is a functional block diagram showing an example of the transmission information storage section 35 according to the present invention. In FIG. 4, the same components as in FIG. 3 are given the same numbers and symbols. In addition to the A storage area 351 and the B storage area 352, the sending information storage section 35 includes an input information buffer storage means 35 for receiving input information.
3. Relay waiting information buffer storage means 354 for receiving relay waiting information; B switching means 35 for switching and connecting incoming information and relay waiting information to one of two storage areas;
5. Transmission information temporary storage means 356 for extracting and temporarily storing transmission information; A for connecting transmission information to the storage area on two sides that is not connected to B switching means 355;
It has a switching means 357 and a sending control means 350. The input information and the relay standby information are sent to the B switching means 35.
The transmission information is shown to be stored in the B storage area 352 via the A switching area, and the transmission information is shown to be taken out from the A storage area 351 via the A switching area.

The details of the storage area are as shown in FIG. 1, in which outgoing information is stored using the location of the terminal device as an address or key, input information and relay standby information as communication information. Upon receiving the first transmission instruction signal, the transmission control means 350 transmits the communication information of the end station device at the position where the number of links to be transmitted is maximized in FIG. are sequentially extracted for multiple pieces of information, and when all of the same DA is sent out, a sending confirmation signal is sent. Since the transmission instruction signal is repeated until the transmission end signal is transmitted, the transmission control means 350 transmits data from the storage area to the terminal equipment in the order from the farthest position to the nearest position (next position).
The communication information is extracted for each DA, and when the transmission is finished as transmission information, a transmission confirmation signal is transmitted.

Next, details of the information transfer control section 38 will be explained with reference to FIG. 5 and FIG. 3. FIG. 5 is a functional block diagram showing an example of a gate drive circuit of an information transfer control section according to the present invention. In Figure 5,
Components that are the same as those in FIG. 3 are given the same numbers and symbols. Newly added blocks in FIG. 5 are AND circuits 387 to 389 and transmission control means 3.
It is 80. The token holding means 381 sends out a token holding signal from the time it receives the TK signal from the reception information identifying section 32, and erases the token with the sending end signal received from the sending information storage section 35. The various information gates are operated by respective signals of the own DA (own DA), other DA, and TK received from the received information identification section 32, and an AND circuit. Acceptance information gate 38
2 opens the gate upon receiving its own DA signal, and transfers the information received from the link to the communication line as acceptance information. The relay information gate 383 receives the output of the AND circuit 387 which inputs the TK signal and the token holding signal, as well as the inverted signal of the token holding signal and others.
The gate is opened using the output of the AND circuit 388 which receives the DA signal as input, and the information received from the link is transferred to the link as relay information. The relay standby information gate 384 receives the token holding signal and other DAs.
The gate is opened using the output of the AND circuit 389 which receives the signal as input, and the information received from the link is transferred to the sending information storage section 35 as relay waiting information. The sending information gate 385 receives the token holding signal, opens the gate, and uses the sending information from the sending information storage section 35 as information to be sent to the link. The token gate 386 opens the gate in response to the transmission end signal from the transmission information storage unit 35, and transfers the token in the form of a token frame as transmission information to the link. The transmission control means 380 repeatedly transmits the transmission instruction signal using the transmission confirmation signal obtained by transmitting the transmission instruction signal while the token holding signal is present.

Next, the flow of communication information will be explained for each token holding state of the information transfer control unit with reference to the drawings. Figures 6a to 6d show the no-token state, the token-receiving state, the token-holding state, and
FIG. 3 is a block diagram showing an example of the present invention when erasing a token. Blocks with the illustrated numbers have the same functions as the constituent elements given the same numbers in FIG. 3, and their explanations will be omitted.

In FIG. 6a, the received information from the link is received by the communication information receiving section 31 and temporarily stored, and when it is the own DA signal, it is determined by the own DA signal or other DA signal identified by the received information identifying section 32. It becomes outgoing information via the acceptance information storage section 33 as acceptance information, and on the other hand, when it is another DA signal, it is sent out as relay information to the link again via the communication information transmission section 37 as transmission information. During this time, information input via the communication line is stored and accumulated in the A storage area 351.

In FIG. 6a, when the received information is a token frame, the information is received from the communication information receiving section 31 to the received information identifying section 32, and a TK signal is outputted, resulting in the state shown in FIG. 6b. In FIG. 6b, the input information while receiving the token is stored and accumulated in the A storage area 351, continuing the state shown in FIG. 6a. The information transfer control unit 38 sends the first transmission instruction signal to the transmission information storage unit 35 based on the token reception, and the transmission information storage unit 35 stores the input information being received in the A storage area 351.
When storage is completed, the A storage area 351 in the storage storage state is switched to the sending state and becomes the state shown in FIG. 6c.

In the state where the token is being held as shown in FIG. That is, the received information becomes acceptance information by the own DA signal and is sent to the acceptance information storage section 33, becomes relay standby information by another DA signal and goes to the B storage area 352, and the token is sent to the communication information transmission section as relay information by the TK signal. 37
are transferred to each. Incoming information from the communication line is stored and accumulated in the B storage area 352 together with relay standby information. On the other hand, the communication information stored in the A storage area 351 forms an information frame including other DAs as sending information, and sends the communication information transmitter 37 with an instruction to send it.
Transferred under the control of a confirmation signal.

FIG. 6d shows a state in which the A storage area 351 is empty and the transmission end signal has reached the information transfer control section 38. The information transfer control section 38 takes out the token from the token frame forming means 362 and transfers it to the communication information transmission section 37. If there is a token being relayed when the transmission end signal is received, after this token frame is transmitted, further token frames are transmitted and the token is erased. During this state of token erasure, the received information is transferred as acceptance information and relay waiting information in the same way as in FIG. 6c, and when the transfer of the information being transferred is completed, FIG.
In, A storage area 351 and B storage area 352
The two are exchanged.

Next, the flow of information in the terminal device A will be explained with reference to FIG. FIG. 7 is a time chart showing an example of the flow of information in the terminal equipment having the functional blocks shown in FIGS. 3 to 5. FIG. In FIG. 7, codes A to F are the codes of terminal equipment, and codes A to B- in the transmission direction of communication information.
The terminal devices are linked in a circular manner in the order C-D-E-F-A. The starting point in FIG. 7 is the state shown in FIG. 6a, and input information C is stored in storage area A with terminal device C as DA. The received information B is transferred to the terminal device B as relay information, and the received information A becomes the acceptance information to the own terminal device A. In the state shown in FIG. 6b, reception of a token is identified by reception information TK, and switching of the A and B storage areas occurs. 6th
In the state shown in Figure c, received information A becomes acceptance information for own terminal device A, reception information TK becomes relay information, other received information is stored and accumulated in B storage area, and incoming information F and B are It is inserted between the received information and stored and accumulated in the B storage area. On the other hand, the sending information from the A storage area becomes the sending information, and the receiving information
TK is inserted into the transmission information as relay information. In the state shown in FIG. 6a, when the transmission of information from the A storage area is completed, the transmission information TK is transmitted and the token is erased. After this state, the A storage area is replaced with the B storage area and the B storage area is replaced with the A storage area in Figure 6 a, b, c, and d (these are referred to as Δa, Δb, Δc, and Δd states).
Therefore, the explanation will be omitted. Also, as shown in the figure, the state in FIG. 6c is the sending state of one storage area A, and the states c, d, and Δa in FIG.
This is the accumulation state of the storage area.

As explained in the above embodiment, in order to increase the token circulation speed of the ring link and prevent multiple tokens from concentrating on a specific terminal device, each terminal device has a memory that accumulates relay waiting information. When transmitting relay standby information by holding a token with two areas, the communication information sent with this token will be the information accumulated in one storage area by the time this token is received, and from that point onwards. The received information is stored in the other storage area so that the token can be released quickly. In addition, just as Yamanote Line trains that run on the tracks adopt the overtaking bus system on the road to avoid the overtaking situation, other token frames that catch up while holding a token are It is sent with an interrupt. In addition, if the token is not held, communication information between other terminal devices will be relayed as is.
Transferring. In this way, communication information sent from a certain terminal device is transferred one after another between subsequent terminal devices that do not hold a token, and when it arrives at a terminal device that holds a token, it is transmitted as relay standby information. Become. On the other hand, each terminal device receives a token based on a token frame sent at the end of transmission of communication information or a token frame interrupted during transmission of communication information. Therefore, the communication information sent before the interrupt token frame will not be relayed by the token at the subsequent terminal device, but the communication information after the interrupt token frame will be transmitted to the nearest terminal device. There is a high possibility that the token will cause a relay wait.

In other words, the information transfer control unit of a certain terminal device obtains a token and sequentially sends the information to the terminal device at the farthest position, so when the next token is interrupted and transferred in the middle of transmission, In a terminal device that receives this token and sends out information, there are many chances that the information to be sent to a terminal device in a closer position than the previous terminal device that is later in the sending order will wait for relaying. There is less chance that information sent to a terminal device located further away than the one in front of the terminal device will be waiting for relay. In addition, as mentioned above, information sent to a nearby terminal device will be relayed by the terminal device holding the interrupt token; Can reach the device.

By the way, if we consider the case where terminal devices holding tokens transmit information in the order of arrival, there is almost no chance that the information sent first to a nearby terminal device will be waiting for relay. However, if the information is sent to the terminal device at the farthest position, in extreme cases, the next terminal device will have to wait for relaying, so there is a possibility that all the terminal devices will have to wait for relaying. Probability (average value) that the transmitted information will be waiting for relay regardless of whether the transmitted information is sent from the farthest or the latest, or in the order of arrival.
are considered to be almost equal, but in terms of dispersion, there are many opportunities for information to be relayed to the farthest terminal device, where the transmitted information is the last, and the delay in information transfer becomes large. .

On the other hand, in the present invention, since information is sent sequentially from the farthest terminal device to the nearest terminal device, the overall chance of waiting for relay is almost equal, but each terminal device There is little variation in the time it takes to transfer information, and the maximum delay time can be reduced. Further, a special device for centrally controlling all terminal devices can be eliminated to control a plurality of tokens.

In the above embodiment, information on input/exit to/from a communication line is illustrated and explained as link reception/transmission information via the terminal device, but communication information between communication lines accommodated and connected to one terminal device is explained. Since the transfer is not related to the circular link, illustration and explanation are omitted. Each part and each means of the illustrated functional block has a central processing unit (CPU).
It can be operated under program control, or some functions can be implemented using hardware, but the central control unit for the entire exchange can perform program control for each functional block. Each functional block, ie, functional division, can be changed into a form suitable for the system by functional organization and configuration using programs and hardware. Therefore, for example, although the transmission control means for sequentially extracting transmission information from the storage area for each end station device from the farthest to the nearest one is installed in the transmission information storage section, it is also possible to install it in the information transfer control section and send out by controlling the retrieval. Show that it is possible.

[Effects of the Invention] As explained above, in the circular link type exchange system of the present invention, the circular link has a plurality of tokens, and while the terminal station forming the circular link does not hold the token, other terminal stations While the communication information between devices is transferred as relay information to the next device, while the token is being received and held, the transmitted information stored and accumulated before the start of token holding is transferred sequentially from the farthest terminal device to the nearest terminal device. By adopting a configuration that transmits the tokens to the device and also transfers the tokens received during this time as relay information to the subsequent device, it is possible to concentrate the tokens in one place without installing a particularly complex control device (dango phenomenon). It is possible to avoid this and shorten the round trip time, to avoid waiting for communication information to be relayed multiple times to a distant terminal device, to average the transfer time (reducing the maximum delay time), and to reduce the storage area of transmitted information. This has the effect of being able to prevent an increase in

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of the present invention, Figure 2 is a block diagram showing the configuration of the present invention.
3 is a functional block diagram illustrating an embodiment of the terminal equipment according to the present invention in FIG. 2, and FIG. 4 is a transmission information storage diagram in FIG. 3. 5 is a functional block diagram showing an example of the gate drive circuit of the information transfer control section in FIG. 3, and FIGS. 6 a to 6 d show the flow of communication information for each token holding state. FIG. 7 is a block diagram showing an example, and a time chart showing an example of the flow of communication information in one terminal device. 21...Switchboard, 22...Communication line, 38...
Information transfer control unit, 211...terminal device, 212...
...link, 350...transmission control means, 351,3
52... Storage area, 361... Information frame forming means, 362... Token frame forming means.

[Claims]

1. In a test method for a plurality of communication control devices connected to a loop-shaped transmission path, one of the communication control devices has a transmitting terminal, a receiving terminal, and a loopback terminal, and a has a selection means for switching between the signal from the transmission path and the signal from the transmission terminal using the signal from the loopback terminal, and when the communication control device is transmitting data, the selection means selects the signal from the transmission terminal. and the receiving terminal so as not to receive the received signal from the transmission path, the transmitted data of the own device is received by the opposite device and also received by the own device, and the transmitted data and the received data are compared. A method for testing a communication control device, characterized in that the communication control device can be tested without relaying communication operations.