JPH0310433A - Reset type communication system - Google Patents

Abstract

PURPOSE:To prevent the consecutive reset waiting state due to the missing reset cell by providing a state consecutive time monitoring timer expiring at the time over one circulation of a transmission line on each node and transiting the time to the normal state simultaneously with the expiration of the time. CONSTITUTION:Each communication node 2 is constituted of a transmission line 1, a cell reception section 3, a call transmission section 4, a management section 5, a reception buffer 6, a transmission buffer 7, and a terminal equipment adaptor section 8. A state consecutive time monitoring time expiring at the time over one circulation of a transmission line is provided on each communication node 2. Then a state consecutive time monitoring timer is started as soon as the state is transferred to the reset waiting state and when the reset waiting state is consecutive till the state consecutive time monitoring timer expires, the state is transferred to the normal state as soon as the timer expires. Thus, the consecutive reset waiting state due to the missing reset cell is prevented.

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention is a reset-type LAN that can be used as a LAN-VAN-WAN by sharing a transmission path among multiple communication nodes and allowing multimedia communications such as data, audio, and images. It is related to communication methods. [Prior art] Traditionally, LANψ systems include the C3MA/CD system (a type of time division multiplexing, in which each node transmits data at a fixed cycle) and the token system (a system that represents transmission rights on the network). There is a method of controlling the network by circulating a piece of data called a token, in which only the node that received the token can send it, and when the transmission is completed, the token is passed to the next node (for example, ``Nikkei Electronics , 114-22 (no, 367) 1985, pp. 185-238).
l Area Network) is on campus, MA
N (Metropolitan AreaNetw
ork) is within the city, WAN (Wide Area
Network) is domestic (wide area), and there are differences in the distances between the connected nodes. These systems have problems such as the inability to improve transmission efficiency and the inability to perform high-quality voice/image communication due to delay time when traffic is heavy. Therefore, prior to the present application, the present inventors solved the above problems and controlled resources by using both a method using a centralized management node and a method of distributed control without using this. proposed a packet switching method that shortens the time required to send a reset after communication ends, can handle multiple priorities, and can recover even when a control bit becomes an error due to a transmission path error (in particular, Gansho 63-50
In the above packet switching system, (a) a busy address area is set in the control information area of the cell, and when each node holds information to be transmitted, the arriving slot ( Set your own address in the busy address area (transmitted by another node) and reserve its use. When the node that has finished transmitting detects its own address in the busy address area, it knows that the pond node has also finished transmitting. (b) The communication interval for high-priority information has ended;
If communication of low-priority information is not completed even after a certain period of time has elapsed, each node terminates communication midway, thereby ensuring high-priority communication. (c) The same transmission path can be shared by the circuit switching method and other communication methods (for example, packet switching method). (d) Not only a method in which transmission line resources are centrally managed by one node, but also a method in which each node manages the use of resources can be adopted. In the latter method, 1
Each node counts the number of cells in the communication section to understand the resource usage status. (e) In distributed control, in order to prevent conflicts when multiple nodes increase resource usage at the same time, each node increases resources after confirming that the usage is below a specified value. (f) When a control bit becomes an error due to a transmission path bit error, a check bit is provided in the cell header so that the error cell can be removed by distributed processing. on and general use nodes turn off the check bit. In the reset type communication method, each communication node is equipped with a counter to record the upper limit of the number of cells to be sent and the number of cells that have already been used, and each communication node transmits cells and transfers information until the upper limit is reached. It can be performed. but,
After sending out the upper limit, for example 10 cells, all communication nodes will not be able to send cells, so by resetting the reset display of the cells that have been circulating, the counter will be reset and the number that has already been used will be set to O. . This allows cells to be sent out many times. As described above, in the conventional reset type communication system, in order to stop the circulation of the reset cell in the transmission path, the node that sent out the reset cell reaps the signal, thereby causing a transition to the normal state. Furthermore, in the xIJ reacquisition waiting state, the control information for generating a reset on each cell reflects the old state since each node was reset, so it was necessary to invalidate it. [Problems to be Solved by the Invention] However, in the above conventional method, (a) if the reset cell is lost, the node in the waiting state for reaping cannot transition to the normal state, and due to the occurrence of a reset on the cell, Since the control information of the node continues to be invalidated, other nodes cannot generate new reset cells. Therefore, there was a problem in that communication between all nodes stopped. (b) If a node waiting for reaping becomes a failure,
Alternatively, if an abnormal reset cell occurs due to a code error on the transmission path, the transmitted reset cell circulates without being harvested, and the counters of each node are reset one after another, so communication between some nodes There was a risk that the use of the cell would be monopolized. The purpose of the present invention is to solve these conventional problems. To provide a reset type communication method capable of maintaining normal cell communication even when a reset cell is lost on a transmission path or when a node waiting for reaping of a reset cell becomes impaired. be.

[Means for Solving the Problems] In order to achieve the above object, the reset type communication system of the present invention (i) connects a plurality of communication nodes with different addresses to a transmission path, and creates a cell consisting of control information and user information. In a communication system that transfers information between arbitrary communication nodes by circulating the cells on the above transmission path, each communication node is equipped with a counter that records the upper limit of the number of usable cells and the number of cells that have already been used. When the communication node detects that the communication node has used cells up to the above upper limit or there is no more information to be transmitted, it sends a reset cell with a reset indication to the transmission path, and at the same time The communication node resets the counter, transitions to a reaping wait state for reaping the reset indication of the next arriving reset cell, transitions to the normal state by reaping the reset cell, and receives another reset cell. In the reset type communication method that resets the above counter. A state duration monitoring timer that times out in a time equal to or more than one revolution of the transmission path is provided in each communication node, and at the same time as the state transitions to the reaping wait state, the state JlkR, time monitoring timer is started, and the state duration monitoring timer is started. The feature is that when the reaping wait state continues until the timeout occurs, the reaping wait state is prevented from continuing due to loss of the reset cell by transitioning to the normal state at the same time as the timeout. (if) each communication node is provided with an abnormal reset cell monitoring timer that times out at a time less than the minimum value of the reset cell generation interval; Another feature is that the abnormal reset cells are prevented from circulating by harvesting the reset cells that arrive before the abnormal reset cell monitoring timer times out without resetting the counter of the node. Furthermore, another feature is that the state duration monitoring timer and the abnormal reset cell monitoring timer are shared by one timer. [Function] In the present invention, (a) each node is provided with a state duration monitoring timer that times out after one rotation of the transmission line, so that the state transitions to the normal state at the same time as the timeout, thereby preventing loss of reset cells. It is possible to prevent the continuation of the waiting state for reaping. That is, even if a reset cell is lost due to a transmission path failure or the like, one communication node can be prevented from remaining in a reaping wait state forever. (b) By providing each communication node with an abnormal reset cell monitoring timer that times out at a time less than the minimum value of the reset cell generation interval, the above monitoring timer is started at the same time as the transition to the normal state, so this timer will not time out. Reset cells that arrived earlier will be pruned to prevent abnormal reset cells from circulating. As a result, it becomes possible to maintain normal reset type communication. (c) Since the state duration monitoring timer and the abnormal reset cell monitoring timer do not operate simultaneously, the device can be simplified by implementing them with one timer. [Example] Hereinafter, an example of the present invention will be described in detail with reference to one drawing. FIG. 1 is a configuration diagram of a communication node showing an embodiment of the present invention. In FIG. 1, I is a transmission path through which cells are sent from adjacent nodes and cells are sent to other adjacent nodes, 2 is a communication node whose configuration is common to all nodes, and 3 is a transmission path through which cells are sent. 4 a cell receiving unit for receiving cells; 4 a cell transmitting unit for transmitting cells; 5 a management unit for controlling headers of transmitted and received cells;
6 is a reception buffer that temporarily stores received cells; 7 is a transmission buffer that temporarily stores transmitted cells; 8 is a terminal support unit that controls the interface with the terminal; and 9 is a terminal. Further, in the transmission buffer 7, transmission queues 71 to 72 for priority orders of a plurality of steels are arranged, and each queue is divided into one for connection and one for connectionless queues. The connection type transmits information after performing a transmission procedure according to the protocol in advance, while the connectionless type transmits information immediately without any prior transmission procedure. When a cell in a cell frame arrives via transmission path l,
The cell receiving section 3 receives this cell. When the destination of the cell is the own communication node, the information therein is transferred to the reception buffer 6 and temporarily stored therein. Receive buffer 6
The information stored in is read out by the terminal support unit 8,
It is sent to the corresponding terminal 9 as user information. Also,
The cell receiving unit 3 transfers control information (cell header) of the received cell to the management unit 5. The management Ig 5 checks the empty bit of the arriving cell, and if it is empty, stores the information to be transmitted from the transmission buffer 7 in the user information field of the cell, and then changes the source address to its own address based on the empty bit. ,
Also, each recipient is set as a recipient address. Then, by transferring this cell to the cell transmitting section 4, it is sent out from the cell transmitting section 4 to the transmission path l. Note that at this time, both the connection method and the connectionless method are supported simultaneously as the packet exchange type. That is, when a transmission procedure is required for the transmission image, connection-based data is transmitted, and when the transmission procedure is not required and the data can be directly transmitted, connection-less data is transmitted. FIG. 2 is a structural diagram of a cell on a transmission path used in the present invention. FIG. 2 shows the structure of layer 1, the structure of cell layer, and the structure of cells. That is, the information on layer 1 includes a cell layer (cell frame), 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 I transmission frame (125 μs) includes information and transmission overhead, that is, a portion for synchronization and the like. A cell frame corresponds to these pieces of information. A cell frame is composed of a portion F such as a framing (for example, a flag composed of a code such as 010101, etc.) and a plurality of cells. Note that there is no problem even if there is no cellteira in the cell. The cell header contains the following information: (i) Cell blockage indication (indicates whether the user information contains valid information); (i) Information source address (address of the communication node that transmits the cell, with the blockage bit set); (it has meaning only when the idle bit is occupied), (iti) information receiving address (destination address for receiving cells, and has meaning only when the idle bit is occupied). (iv) Access control information area (used to detect the end of transmission from other communication nodes), (V) Reset bit (indicates that it is a reset cell indicating transition to the next communication section). FIG. 3 is a diagram showing types of communication network configurations in the present invention. FIG. 3(a) shows a ring network in which communication node 2 is actively connected to transmission path l, and FIGS. 3(b) to (e) show a ring network in which communication node 2 is passively connected to transmission path l. A connected bus network. Figure 3(b) shows a case where there are multiple headends in the network, and each node has multiple cell receivers and cell transmitters, and Figure 3(c) shows a case where there are multiple headends in the network. Figure 3(d) shows the case where there is a single headend in the network and each node has a single cell receiving section and a single cell transmitting section. This is a case where there are multiple cell receiving units and cell transmitting units, and as shown in Fig. 3 (e
) is the case where there is a single headend in the network and a single cell receiver and cell transmitter at each node. In a bus network, a head end 10 that generates transmission frames is required, and the head end IO must send the received cells to another transmission path to circulate the cells. The function of the headend 10 is that the nearest communication node 2
There is no problem for someone to act on your behalf. Each node 2 has a different address, and if one node has multiple cell receiving sections and cell transmitting sections as shown in FIG. 3(b) and (d), different addresses are used for each node. . Information in the form shown in FIG. 2 flows through the transmission path l. In that case, a cell frame is used to detect the beginning of the cell used by each communication node. As mentioned above, at the beginning of the cell frame, 010101
Since a flag consisting of a code such as . One communication node can transmit information using a predetermined number of cells within a communication interval. For example, a transmission path configuration as shown in FIGS. 3(a) and 3(b) can be used, but it does not necessarily have to be a ring configuration. Of course, a straight line form as shown in FIG. 3(b) may also be used. However, in this case, the communication nodes at both ends are
It is necessary to send cells received on one transmission path to the other transmission path to circulate them. By configuring each communication node with an active circuit type as shown in Fig. 3(a), a cell can be terminated with one communication node, but with a passive circuit type as shown in Fig. 3(b). By configuring each communication node, a cell frame may be transmitted by one communication node. Note that the functionality of the headend 10 is required only in the case of passive circuits. In other words, in active type circuits, the communication node creates a signal and sends out the cell in addition to the manually input signal, but in passive type circuits, the manually input signal is used as it is to relay the cell, so the content of the cell is first read. You will need a place to create it. The head end 10 has the function of first creating a cell and sending it out to the transmission path. FIG. 4 is a diagram showing the state transition of each communication node in the reset type communication system according to the present invention. A plurality of communication nodes A, B, C, . . . each have a different address and are actively or passively connected to a transmission path. Each communication node is provided with a counter that records the upper limit of the number of usable cells determined from the throughput and delay conditions required for communication and the number of cells that have already been used. When any communication node or all communication nodes detects that cells have been used up to the above upper limit or that there is no more information to be transmitted, the above counters of all nodes are reset. An arbitrary communication node or a specific communication node transmits a cell with a reset indication (reset cell) and at the same time transitions to a state (reaping wait state) in which it reaps the reset indication of the next arriving reset cell. Next, the communication node transitions to the normal state by reaping the reset indication. In this way, it is possible to ensure fair use of transmission paths between communication nodes. When node A in FIG. 4 determines that all nodes have stopped transmitting information using the control information on the cell, it resets the counter and sends out a reset cell, and enters the waiting state for reaping. Transition. When other nodes B and C receive a reset cell via the transmission path, they confirm that the destination is not their own node and relay it as is, reset their counters, and transition to a new normal state. . The communication node A in the reaping wait state reaps the circulating reset cells and transits to the normal state. In the same way, after confirming that node C is in the transmission stop state, it resets the counter and sends out a reset cell, and nodes A and B in the pond relay this cell to the nodes waiting to be harvested. Node C harvests the cells it has orbited. Thereafter, each communication node repeats the sending, relaying, and reaping processes of the reset cell in the same manner. FIG. 5 is a functional explanatory diagram of the state duration monitoring timer according to the present invention. First, when node A sends out a reset cell, it transits to the reaping wait state and simultaneously starts a state duration monitoring timer. In normal operation, considering the case where a plurality of communication nodes generate reset cells at the same time, a transition to the communication status monitoring state occurs in less than one rotation of the transmission path. That is, before the state duration monitoring timer times out, the reset cell comes around and is harvested. On the other hand, if the reset cell sent by node C is lost after being relayed by node A,
The reaping wait state continues in node C, the state duration monitoring timer times out, and the node C transitions to the communication status monitoring state. As a result, node C determines that the previously sent reset cell has been lost. The timeout period is set to be at least one round of the transmission path so as not to affect 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 upon receiving a reset cell generated by another node, that node starts the abnormal reset cell monitoring timer. The abnormal reset cell monitoring timer is set to time out less than the expected minimum arrival interval Tsin of reset cells. That is, in general, the minimum interarrival interval T
, , is a value that is sufficiently larger than the time for one round of the transmission path. In normal operation, the arrival interval of reset cells is equal to or greater than the minimum arrival interval T, , 1, but in the case of a communication node failure, the time for cell pruning processing is omitted; The abnormal reset cell circulates in one cycle of the transmission line. Therefore,
If a reset cell arrives at ni when the abnormal reset cell monitoring timer times out, this can be regarded as an abnormal reset cell, so the communication node that detected the abnormality reaps the reset cell. In FIG. 6, first, node A sends out a reset cell and transitions to the reaping wait state, and then node B relays this reset cell and starts an 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, since the circulating reset cells are harvested when they arrive at node A, no abnormal reset cells are detected. Next, if a node failure occurs after node C sends out a reset cell, the cell will be relayed by node A, the abnormal reset cell monitoring timer will start, the cell will be relayed by node B, and the cell will be relayed by node B. The reset cell monitoring timer starts. In this case,
Since a failure has occurred in node C, it is not possible to harvest at node C, so the crop arrives at node A before the abnormal reset cell monitoring timer times out. As a result, node A determines this cell to be an abnormal reset cell and harvests 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. The state duration monitoring timer is effective when the node is in the reaping wait state, and the abnormal reset cell monitoring timer is effective when the node is in the normal state, so they can be implemented 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 timeout expires. It is in normal condition. Next, this node sends out a reset cell, starts a state duration monitoring timer, and transitions to a reaping wait state. In this case, since the reset has arrived due to a timer timeout, this reset cell is harvested and an abnormal reset cell monitoring timer is started. Since no reset cell arrives before the abnormal reset cell monitoring timer times out, there is no abnormal reset. Thereafter, it relays the reset cells sent by other nodes and starts an abnormal reset cell monitoring timer. As described above, in this embodiment, (a) by using the state duration monitoring timer, it is possible to prevent the communication node from remaining in the reaping wait state forever. That is, even if a reset cell is lost due to a transmission path failure, etc., this can be detected. (b) Furthermore, by using the abnormal reset cell monitoring timer, it is possible to prevent abnormal reset cells from circulating without being harvested. (c) Furthermore, by implementing the state duration monitoring timer and the abnormal reset cell monitoring timer, which do not operate simultaneously, into one timer, the device can be simplified. [Effects of the Invention J As explained above, according to the present invention, by using one timer, when a reset cell is lost on a transmission path, or when a node waiting to harvest a reset cell becomes a failure. Even in such cases, it is possible to maintain normal reset type communication.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of each communication sword showing an embodiment of the present invention, FIG. 2 is a configuration diagram of cells on a transmission path in the present invention, and FIG. 3 is a diagram of a communication network configuration to which the present invention is applied. FIG. 4 is a state transition diagram of the reset cell and each node of the reset type communication system according to the present invention, FIG. 5 is an explanatory diagram showing the function of the state duration monitoring timer according to the present invention, and FIG. 6 is an abnormal reset according to the present invention. An explanatory diagram showing the functions of the cell monitoring timer,
FIG. 7 is a functional explanatory diagram when a state duration monitoring timer and an abnormal reset cell monitoring timer are realized by a single timer according to the present invention. 1: Transmission path, 2: Communication node, 3: Cell receiving section, 4: Cell transmitting section, 5: Management section, 6: Receiving buffer, 7: Transmitting buffer, 71, 72: Priority 1 to transmission queue ,
8: Terminal support section, 9: Terminal, IO: Head end. Figure 3 (Part 2) cL Multiple IT, end-end single access bus network d) Single head-end multiple access bus network procedural amendment (voluntary) August 25, 1999

Claims (3)

[Claims] (1) Used in a communication method that transfers information between arbitrary communication nodes by connecting multiple communication nodes with different addresses to a transmission path and circulating cells containing control information and user information on the transmission path. A counter is installed in each communication node to record the upper limit of the number of possible cells and the number of cells that have already been used, and it is possible to detect when all communication nodes have used cells up to the above upper limit or have no more information to send. The detected communication node sends 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 transitions to a reaping state for reaping the reset indication of the reset cell that arrives next, In a reset type communication system in which a communication node that transitions to a normal state by reaping the reset cell and receives another reset cell resets the counter, state duration monitoring that times out in a time equal to or longer than one rotation of the transmission path. A timer is provided in each communication node, and the state duration monitoring timer is started at the same time as the state transitions to the reaping state, and if the state duration monitoring timer continues to be in the reaping wait state until the timer times out, the timer is started at the same time as the timeout. A reset type communication system characterized by preventing continuation of a reaping wait state due to loss of a reset cell by transitioning to a normal state. (2) Each communication node is provided with an abnormal reset cell monitoring timer that times out in a time less than the minimum value of the reset cell generation interval, and starts the abnormal reset cell monitoring timer at the same time as it transitions to the normal state, and 2. The reset type communication system according to claim 1, wherein the reset cell that arrives before the reset cell monitoring timer times out is harvested without resetting the counter of the node, thereby preventing the abnormal reset cell from circulating. . (3) The reset type communication system according to claim 1 or 2, characterized in that the state duration monitoring timer and the abnormal reset cell monitoring timer are shared by one timer.