JP2679251B2 - Reset type communication method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is capable of sharing a transmission line with a plurality of communication nodes and performing multimedia communication of data, voice, images, etc. -It relates to a reset type communication method that can be used as a WAN.

[Conventional technology]

Conventionally, as the LAN method, the CSMA / CD method (after confirming that the transmission line is unused, sends the data,
When it collides with the data sent by another node, it detects this and retransmits it, or a token method (a method of circulating one piece of data called a token representing a transmission right on the network to control the network, Only the node that received the token can send it, and when the sending is completed, pass the token to the next node) (for example, “Nikkei Electronics” 4-22 (no.367) 1985 pp.186 terminology explanation ( CSMA / CD method column))). LAN (Local
Area Network) is on campus, MAN (Metropolitan Area Netwo)
rk) is in the city, WAN (Wide Area Network) is domestic (wide area)
However, there is a difference in the distance between the coupled nodes.

With these methods, when the traffic is heavy, the transmission efficiency does not increase and the quality of voice
There were problems such as inability to perform image communication.

Therefore, the inventors of the present invention solve the above problems and control the resources by using both the method using the centralized management node and the method for distributed control without using the centralized management node, prior to the present application. , Proposed a packet switching method that shortens the time required to send a reset after the end of communication, can handle multiple priorities, and can recover even if an error occurs due to a transmission line error in a control bit. Sho 63-5031
No. 0 specification and drawings). In the above packet switching method, (a) the busy address area is set in the control information area of the cell, and when each node holds the information to be transmitted, the busy slot (arriving by another node) that arrives Make your reservation by setting your own address in the address area. When the node that has completed transmission detects its own address in the busy address area, it is known that the transmission of other nodes has also completed. (B) When the communication section for high priority information ends and the communication for low priority information does not end even after a certain period of time, each node terminates the communication in the middle to guarantee high priority communication. To do. (C) The same transmission line can be shared by the circuit switching system and other communication systems (for example, packet switching system). (D) Not only a method of centrally managing transmission path resources by one node, but also a method of managing resource use by each node can be adopted. In the latter method, each node counts the number of cells in the communication section to grasp the resource usage status. (E) With distributed control,
To prevent collisions when multiple nodes increase resource usage at the same time, increase the resource after confirming that each node is below the specified value. (F) When a control bit causes an error due to a transmission line bit error, a check bit is provided in the cell header so that the error cell can be removed by distributed processing. Turn on, general use node turns off check bit.

In the reset-type communication method, each communication node is provided with a counter for recording the upper limit value of the number of cells to be sent and the number of already used cells, and until the upper limit value is reached, cells are sent from each communication node to transfer information. It can be performed. However, after sending the upper limit value, for example, 10 cells, all communication nodes cannot send cells, so by turning on the reset display of the orbiting cells, the counter is reset and the number already used is displayed. Set to 0. This allows the cell to be sent many times.

As described above, in the conventional reset-type communication method, since the circulation of the reset cell is stopped in one round of the transmission line, the node that has transmitted the reset cell cuts the transition to the normal state. Further, in the reaping waiting state, the control information for the occurrence of reset on each cell reflects the old state before each node was reset, so it was necessary to invalidate this.

[Problems to be solved by the invention]

However, in the above conventional method, (a) when the reset cell is lost, the node in the reaping waiting state cannot transition to the normal state, and the control information for reset occurrence on the cell continues to be invalidated. Other nodes will not be able to generate new reset cells. Therefore, there is a problem that communication of all nodes is stopped.

(B) When a node waiting for reaping fails
Alternatively, if an abnormal reset cell occurs due to a code error on the transmission path, the reset cell that has been sent circulates without being clipped, and the counters of each node are reset one after another, so communication between some nodes There was a risk that the use of cells would be monopolized.

An object of the present invention is to solve these conventional problems and maintain normal cell communication even when a reset cell is lost on the transmission path or when a node in a state waiting for reaping of the reset cell fails. It is to provide a reset type communication system capable of performing.

[Means for solving the problem]

In order to achieve the above object, the reset type communication system of the present invention comprises: (i) connecting a plurality of communication nodes having different addresses to a transmission line, and circulating a cell including control information and user information on the transmission line. , In a communication method in which information is transferred between arbitrary communication nodes, each communication node is provided with a counter for recording the upper limit value of the number of usable cells and the number of already used cells, and all the communication nodes keep the cells up to the above upper limit value. A communication node that detects that it is in a used state or a state where there is no information to be transmitted sends out a reset cell with a reset indication to the transmission path, and at the same time, resets the counter of its own communication node and arrives next. The reset display of the reset cell shifts to the cutting waiting state for cutting, and the cutting of the reset cell causes the state to shift to the normal state. In the reset-type communication method in which the communication node that has received the reset cell resets the counter, each communication node is provided with a state duration monitoring timer that times out for a period of time equal to or more than one round of the transmission path, and at the same time when it shifts to the reaping waiting state. , The state continuation time monitoring timer is started, and when the retrieving waiting state continues until the state continuation time monitoring timer times out, by transitioning to the normal state at the same time as the timeout, the retrieving waiting state due to loss of reset cell It is characterized by preventing the continuation of. Further, (ii) each of the communication nodes is provided with an abnormal reset cell monitoring timer that times out in a time period less than the minimum value of the reset cell generation interval, and the abnormal reset cell monitoring timer is started at the same time when transitioning to a normal state, Another feature of the present invention is that the reset cells that arrive before the abnormal reset cell monitoring timer times out are pruned without resetting the counter of the node, thereby preventing the abnormal reset cells from going around. Further, (iii) the state duration monitoring timer and the abnormal reset cell monitoring timer are shared by one timer.

[Action]

In the present invention, (a) by providing each node with a state duration monitoring timer that times out for a time longer than one round of the transmission line, the state transitions to the normal state at the same time as the time-out. Can be prevented from continuing. That is, even if the reset cell is lost due to a transmission path failure or the like, it is possible to prevent the communication node from permanently continuing to be in the cutting waiting state. (B) By providing each communication node with an abnormal reset cell monitoring timer that times out in a time less than the minimum value of the reset cell generation interval, the above monitoring timer is started at the same time as a transition to the normal state, so this timer times out. The reset cell that arrived earlier will be clipped to prevent the abnormal reset cell from wrapping around. as a result,
It is possible to maintain normal reset-type communication.
(C) Since the state duration monitoring timer and the abnormal reset cell monitoring timer do not operate at the same time, by realizing them with one timer, the device can be simplified.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of a communication node showing an embodiment of the present invention.

In FIG. 1, 1 is a cell sent from an adjacent node,
Also, a transmission path through which cells are sent to other adjacent nodes, 2 is a communication node whose configuration is common to all nodes, 3 is a cell receiving unit that receives the sent cells, and 4 is a cell transmitting unit that sends the cells. Reference numeral 5 is a management unit that controls the headers of transmission / reception cells, 6 is a reception buffer that temporarily stores received cells, and 7
Is a transmission buffer that temporarily stores transmission cells, 8 is a terminal corresponding unit that controls an interface with the terminal, and 9 is a terminal. Further, a plurality of transmission queues for priority 71 to 72 are arranged in the transmission buffer 7 and are divided into connection queues and connectionless queues, respectively. The connection type is for transmitting information after performing a protocol-based transmission procedure in advance, and the connectionless type is for transmitting information immediately without any advance transmission procedure.

When a cell in the cell frame arrives via the transmission path 1, the cell receiving unit 3 receives this cell. Then, when the destination address of the cell is the own communication node, the information therein is transferred to the reception buffer 6 and temporarily stored. The information stored in the reception buffer 6 is read out by the terminal correspondence unit 8 and sent to the corresponding terminal 9 as user information. In addition, the cell reception unit 3 transfers the received control information (cell header) of the cell to the management unit 5. The management unit 5 inspects the vacancy block bit of the arrived cell, stores the information to be transmitted from the transmission buffer 7 in the user information field of the cell when it is vacant, then vacates the block bit, and sets the transmission source to the own address. , And the recipient is set to the recipient address. Then, by transferring this cell to the cell transmission / reception unit 4, the cell transmission unit 4 sends it to the transmission line 1. In addition,
At this time, both the connection method and the connectionless method are simultaneously supported as packet switching types. That is, when the transmission procedure is required before the transmission, the connection method data is transmitted, and when the other party who does not need the transmission procedure and can be directly transmitted, the connectionless method data is transmitted.

FIG. 2 is a structural diagram of a cell on the transmission line used in the present invention.

FIG. 2 shows the structure of layer 1, the structure of cell layer and the structure of cell. That is, the cell layer (cell frame) is included in the information of layer 1, and one cell is included in the cell frame. One cell consists of a cell header, user information, and a cell tailor.

That is, the layer 1 transmission frame (125 μs) contains information and transmission overhead, that is, a portion for the period and the like. The cell frame corresponds to these pieces of information. A cell frame is composed of a portion F for framing (for example, a flag composed of a code such as 010101 ...) And a plurality of cells. The cell tailer in the cell may be omitted. The cell header contains the following information.

(I) cell empty / occluded indication (indicating whether or not valid information is included in user information), (ii) information source address (address of communication node transmitting cell, and empty / occluded bit is (It has meaning only when it is closed), (iii) Information receiving address (destination address that receives a cell, and has meaning only when the empty block bit is closed), (iv) Access control information area ( (Used to detect transmission end of other communication node), (v) Reset bit (indicates that the cell is a reset cell indicating transition to the next communication section).

FIG. 3 is a diagram showing types of communication network forms in the present invention.

FIG. 3 (a) is a ring network in which the communication node 2 is actively connected to the transmission line 1, and FIG. 3 (b) to (e).
Is a bus network in which the communication node 2 is passively connected to the transmission line 1. FIG. 3 (b) shows a case where a plurality of headends exist in the network and a plurality of cell reception units and cell transmission units exist in each node, and FIG. 3 (c) shows a plurality of them in the network. In FIG. 3D, there is a single headend in the network and each node has a single cell receiving unit and a cell transmitting unit. In the case where there are a plurality of cell receiving units and cell transmitting units, in FIG. 3 (e), there is a single headend in the network, and each node has a single cell receiving unit and cell transmitting unit. If it exists.

In the bus network, a head end 10 that generates a transmission frame is required, and the head end 10 needs to send the received cell to another transmission path to circulate the cell. The function of the headend 10 may be performed by the nearest communication node 2 instead. Each node 2 has a different address, and when one node has a plurality of cell reception units and cell transmission units, as shown in FIGS. 3B and 3D, different addresses are used. .

Information of the form shown in FIG. 2 flows through the transmission line 1. In that case, a cell frame is used to detect the head of a cell used by each communication node. As mentioned above, since the flag composed of codes such as 010101 ... Is provided at the beginning of the cell frame, it is possible to know the beginning of the cell group used by a certain communication node by detecting this flag. You can One communication node can transmit information using a predetermined number of cells within a communication period.

For example, the form of the transmission line as shown in FIGS. 3 (a) and 3 (b) can be used, but the form of the transmission line is not necessarily required. Of course, the linear form as shown in FIG. 3 (b) does not matter. However, in this case, the communication nodes at both ends need to cyclically transmit the cells received on one transmission path to the other transmission path.

By configuring each communication node with an active circuit type as shown in FIG. 3 (a), it is possible to terminate a cell with one communication node, but with a passive circuit type as shown in FIG. 3 (b). The configuration may be such that one communication node transmits a cell frame by configuring each communication node.

It should be noted that the function of the headend 10 is necessary only in the case of a passive circuit. In other words, in an active circuit, a communication node creates a signal and sends out a cell separately from the input signal, but in a passive circuit, the input signal remains unchanged and the cell is relayed. You need a place to create it. The headend 10 has a function of first creating a cell and sending it to the transmission path.

FIG. 4 is a diagram showing state transition of each communication node of the reset type communication system according to the present invention.

The plurality of communication nodes A, B, C, ... Have different addresses, and are actively or passively connected to the transmission path. Each communication node is provided with a counter for recording the upper limit of the number of usable cells determined from the throughput and delay conditions required for communication, and the number of cells already used. If any communication node or all communication nodes detect the state of using the cell up to the upper limit value or the state that there is no information to be transmitted, respectively, in order to reset the counter of all nodes, the above An arbitrary communication node or a specific communication node transmits a cell with a reset indication (reset cell) and, at the same time, transits to a state of cutting off the reset indication of the next arriving reset cell (cutting waiting state). Next, the communication node transits to the normal state by cutting the reset display. In this way, fair use of the transmission path among the communication nodes can be guaranteed.

When node A in FIG. 4 uses the control information on the cell to determine that all nodes have stopped transmitting information, it resets the counter and sends a reset cell to enter the reaping waiting state. Transition. When the reset cell is sent via the transmission line, the other nodes B and C confirm that the destination is not their own node and relay it as they are, and reset the counter and make a transition to a new normal state. The communication node A in the reaping waiting state
The orbiting reset cell is cut off and the normal state is entered. Similarly, after confirming that the node C is in the transmission stopped state, the counter is reset and the reset cell is transmitted, and the other nodes A and B relay the cell and the node C in the reaping waiting state. Reap the cells that were circling. Thereafter, in the same manner, each communication node repeats the reset cell transmission, relay, and reaping processing.

FIG. 5 is a functional explanatory diagram of the state duration monitoring timer according to the present invention.

First, when the node A sends the reset cell, the state continuation monitoring timer is started at the same time as the state transitions to the reaping waiting state. In normal operation, in consideration of the case where a plurality of communication nodes generate reset cells at the same time, the state transitions to the normal state within a time period of one round of the transmission path or less. That is,
Before the state duration monitoring timer times out, the reset cell goes around, so it is cut off.

On the other hand, if the reset cell transmitted by the node C is relayed by the node A and then the reset cell is lost, the reaping waiting state continues in the node C, and the state duration monitoring timer times out. , Transition to the communication status monitoring state. Thereby, the node C determines that the reset cell transmitted previously is lost.

The time-out period is one or more rounds of the transmission line so as not to affect the normal operation.

FIG. 6 is an explanatory diagram of the function of the abnormal reset cell monitoring timer according to the present invention.

Each node is provided with an abnormal reset cell monitoring timer, and when a reset cell generated by another node is received, that node starts the abnormal reset cell monitoring timer. The abnormal reset cell monitoring timer is set to time out within the expected minimum arrival time _Tmin of reset cells. That is, in general, the minimum arrival interval T _min
Is a value sufficiently larger than the time taken for one round of the transmission path.

In the normal operation, the reset cell arrival interval is equal to or greater than the minimum arrival interval T _min , but in the case of a communication node failure,
An abnormal reset cell circulates in one round of the transmission line. Therefore, if a reset cell arrives before the abnormal reset cell monitoring timer times out, this can be regarded as an abnormal reset cell, and the communication node that has detected the abnormality reaps the reset cell.

In FIG. 6, first, the node A sends a reset cell, and after transitioning to the reaping waiting state, the node B relays this reset cell, starts the abnormal reset cell monitoring timer, and the next node C also This reset cell is relayed and an abnormal reset cell monitoring timer is started. In this case, the reset cell that has circulated is clipped when it arrives at the node A, so that no abnormal reset cell is detected. Next, when the node C becomes a node failure after sending out the reset cell, the cell is relayed at the node A, the abnormal reset cell monitoring timer is started, and the cell is relayed at the node B as well. The reset cell monitoring timer starts. In this case, since the node C has failed and cannot be reaped by the node C, the node C arrives at the node A before the abnormal reset cell monitoring timer times out. As a result, the node A judges this cell as an abnormal reset cell and cuts the abnormal reset cell.

FIG. 7 is a functional explanatory diagram when the functions of the state duration monitoring timer and the abnormal reset cell monitoring timer are realized by one timer according to the present invention.

Since the state duration monitoring timer is valid when the node is in the reaping waiting state and the abnormal reset cell monitoring timer is valid when the node is in the normal state, it can be realized by using the same timer. That is, as shown in FIG. 7, when the state of a certain node is shown, after the abnormal reset cell monitoring timer is started at the time when the reset cell of another node is relayed, the cell does not arrive before the time-out. It is in a normal state. Next, the reset cell is sent from this node, the state duration monitoring timer is started, and the state transitions to the reaping waiting state.
In this case, since the reset arrives before the timer times out, the reset cell is cut off and the abnormal reset cell monitoring timer is started. Since the reset cell does not arrive before the abnormal reset cell monitoring timer times out, there is no abnormal reset. After that, the reset cell sent by another node is relayed and the abnormal reset cell monitoring timer is started.

As described above, in the present embodiment, by using (a) the state duration monitoring timer, it is possible to prevent the communication node from continuing in the mowing waiting state forever. That is, even if the reset cell is lost due to a transmission path failure or the like, it can be detected.

(B) Further, by using the abnormal reset cell monitoring timer, it is possible to prevent the abnormal reset cell from going around without being cut.

(C) Further, by realizing the state duration monitoring timer and the abnormal reset cell monitoring timer that do not operate at the same time with one timer, the device can be simplified.

〔The invention's effect〕

As described above, according to the present invention, by using one timer, even if the reset cell is lost on the transmission line or the node in the reset cell reaping waiting state fails, the normal operation is performed. The reset type communication can be maintained.

[Brief description of the drawings]

FIG. 1 is a block diagram of each communication node showing an embodiment of the present invention, FIG. 2 is a block diagram of cells on a transmission line in the present invention,
FIG. 3 is a diagram of a communication network form to which the present invention is applied, FIG. 4 is a state transition diagram of a reset cell and each node of the reset type communication system in the present invention, and FIG. 5 is a state duration monitoring timer according to the present invention. 6 is an explanatory view showing the function of the abnormal reset cell monitoring timer according to the present invention, and FIG. 7 is a single timer for realizing the state duration monitoring timer and the abnormal reset cell monitoring timer according to the present invention. It is a functional explanatory view in the case of doing. 1: transmission line, 2: communication node, 3: cell reception unit, 4: cell transmission unit, 5: management unit, 6: reception buffer, 7: transmission buffer, 71, 7
2: Transmission queue for priorities 1 to n, 8: Terminal corresponding part, 9: Terminal, 10: Headend.

 ─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A 1-223852 (JP, A) JP-A 1-114134 (JP, A) JP-A 63-42248 (JP, A) JP-A 61- 71742 (JP, A) JP 57-150255 (JP, A) JP 3-104340 (JP, A) European publication 256681 (EP, A1)

Claims (3)

(57) [Claims] 1. A communication system in which information is transferred between arbitrary communication nodes by connecting a plurality of communication nodes having different addresses to a transmission line and circulating a cell consisting of control information and user information on the transmission line. , Each communication node is provided with a counter for recording the upper limit value of the number of usable cells and the number of already used cells, and all the communication nodes are in a state of using the cells up to the upper limit value or there is no information to be transmitted. When the communication node that detects that the reset cell is transmitted to the transmission line at the same time as resetting the above counter of its own communication node, transitions to the reaping waiting state for reaping the reset indication of the next arriving reset cell. However, the communication node that has received another reset cell after transitioning to the normal state by cutting off the reset cell resets the counter. In the reset type communication method, the state continuation time monitoring timer that times out for a time longer than one round of the transmission path is provided in each communication node, and the state continuation time monitoring timer is started at the same time when the state transitions to the reaping waiting state. However, when the reaping waiting state continues until the state continuation time monitoring timer times out, a transition to the normal state occurs at the same time as the time-out, thereby preventing the reaping waiting state from being lost due to a reset cell being lost. Reset type communication method. 2. Each of the communication nodes is provided with an abnormal reset cell monitoring timer that times out in a time period less than the minimum value of the reset cell generation interval, and the abnormal reset cell monitoring timer is started at the same time when a transition is made to a normal state, The reset type according to claim 1, wherein the reset cell that arrives before the abnormal reset cell monitoring timer times out is pruned without resetting the counter of the node to prevent the abnormal reset cell from going around. Communication method. 3. The reset communication system according to claim 1, wherein the state duration monitoring timer and the abnormal reset cell monitoring timer are shared by one timer.