JP2004254188A - Communication network and transmission control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication network and a transmission control method for avoiding generation of a waiting state for a useless packet and reduction of throughput even when congestion control is performed. <P>SOLUTION: Each node has a buffer for temporarily storing the received packets by every one of a plurality of transmission lines for connecting nodes. When congestion is detected by a congestion detection means which monitors the number of packets stored in the buffer, the congestion detection means informs a node at the previous stage of a transmission channel number in which the congestion is generated. The node which has received congestion information suppresses or stops transmission of the packet to be transmitted to nodes at the next stage and subsequent stages via the node at the next stage to the informed transmission channel. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a communication network and a transmission control method thereof, and more specifically, a communication network including a plurality of node devices for connecting a plurality of terminal devices and a plurality of transmission channels for connecting between the node devices, And a transmission control method for transmitting a packet in the communication network.
[0002]
[Prior art]
In recent years, a network in which node devices are connected by a multiplex transmission line having a plurality of transmission channels has been studied in order to respond to a demand for a high-speed and large-capacity communication network. For example, JP-A-8-237306 discloses an example of this type of network. Here, signals to be transmitted are temporarily stored in a plurality of buffers provided for each transmission channel, and signals in each buffer are transmitted so that signals from a plurality of buffers are not transmitted to one transmission channel at the same time. There has been proposed a network that enables high-speed communication with a simple configuration by performing control to change a transmission channel in a predetermined pattern.
[0003]
In general, packet discarding due to buffer overflow during heavy load in a network is a major problem. Discarding a packet causes retransmission of communication data, which is a major factor in reducing the throughput. Although it is possible to reduce the packet discard by increasing the buffer amount in the node device, this is not enough, and the hardware scale is increased. Therefore, it is necessary to perform congestion control that performs control to minimize packet discard even under high load and prevents a decrease in throughput.
[0004]
Conventionally, as one method of congestion control, when congestion occurs, a back pressure type congestion control method that avoids packet discarding by controlling to temporarily stop packet transfer to a preceding node device. It has been known.
[0005]
[Problems to be solved by the invention]
However, when such a back pressure control method is applied to a network as described above, in a preceding node device instructed to stop packet transfer, a packet in a buffer in which congestion occurs in a next node device is generated. Transfer of all packets is stopped irrespective of whether or not the packet is passed, and a waiting state (Head of Line Blocking) occurs even for packets that do not originally affect the congestion, resulting in a problem that the throughput is reduced. there were.
[0006]
An object of the present invention is to solve the above-mentioned problems and to provide a communication network and a transmission control method capable of avoiding a decrease in throughput even when congestion occurs.
[0007]
[Means for Solving the Problems]
The communication network according to the present application is configured as follows.
[0008]
A communication network in which a plurality of node devices are connected by a plurality of transmission channels to transmit a packet, wherein the node device includes a buffer unit for temporarily storing a packet to be transmitted for each of the plurality of transmission channels. A congestion detection unit that monitors the number of packets stored in each of the buffer units and detects occurrence of congestion, and corresponds to the buffer unit in which congestion is detected when congestion is detected by the congestion detection unit. A transmission channel, a congestion notification transmitting unit for notifying the preceding node device, a congestion notification receiving unit for receiving a congestion notification from another node device, and a notification based on the congestion notification received by the congestion notification receiving unit. And a packet transmission control means for suppressing or stopping transmission of a packet to the selected transmission channel.
[0009]
A communication network for connecting a plurality of node devices with a plurality of transmission channels and transmitting packets, wherein the node devices temporarily store received packets corresponding to each of the transmission channels. A transmission channel for outputting packets stored in each of the buffer units is sequentially changed in a predetermined order and simultaneously so that packets from each of the buffer units are output to different transmission channels. A switch means for monitoring the number of packets stored in each of the buffer means, and detecting the occurrence of congestion; and a buffer means for detecting congestion when the congestion detection means detects congestion. Congestion notification transmitting means for notifying the preceding node device of the transmission channel corresponding to Notification receiving means, based on the congestion notification received by the congestion notification receiving means, the period during which the output transmission channel of each buffer means is set to the notified transmission channel, is stored in the buffer means A communication network comprising: packet transmission control means for suppressing or stopping packet transmission.
[0010]
Further, based on the congestion notification received by the congestion notification receiving means, the transmission of a packet transmitted to the notified transmission channel via the next-stage node device to the next-stage node device is suppressed or A communication network comprising a packet transmission control means for stopping.
[0011]
(Action)
According to the present invention, when congestion occurs in a certain node device, the location (transmission channel) where the congestion has occurred is notified to the preceding node device, and the location where the congestion occurs is notified in the preceding node device. By suppressing or stopping only the transmission of packets passing through, it is possible to avoid a decrease in throughput due to congestion control.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
The present invention will be described with reference to a reference example which is useful for explaining the present invention and which basically overlaps with the embodiment of the present invention.
[0013]
FIG. 5 is a configuration diagram of a node device in the network of the reference example, and shows an example in which terminal devices 551 to 558 are connected to the node device 500 via sub-transmission paths.
[0014]
Reference numerals 521 to 528 and 531 to 538 denote multiplex transmission lines having a plurality of transmission channels. For example, a plurality of (eight in this configuration example) optical fiber transmission lines spatially separated or one optical fiber is used. This is the wavelength multiplex transmission line used.
[0015]
Reference numerals 501 to 508 denote separation / insertion units that detect destination addresses of packets input from the multiplex transmission paths 521 to 528, and based on the destination addresses, determine whether packets transmitted to the terminals 551 to 558 via the sub transmission paths are detected. , And a function of separating packets input to the buffer units 511 to 518 into packets and inputting the packets input from the terminal to the packet stream input from the multiplex transmission path.
[0016]
Reference numerals 511 to 518 denote buffer units for temporarily storing packets output from the separation / insertion unit in a storage area corresponding to each output terminal of the switch unit 541 or a FIFO memory connected to an arbitrary output terminal of the switch unit. Has functions.
[0017]
Reference numeral 541 denotes a switch unit that connects the packets input to the input terminals IN1 to IN8 to the output terminals OUT1 to OUT8 under the control of the switch control unit 542. When using a plurality of spatially separated optical fiber transmission lines as a multiplex transmission line, the switch unit 541 is configured using a space switch or the like.
[0018]
Reference numeral 542 denotes a switch control unit, which controls the switch unit 541 according to a connection table shown in FIG.
[0019]
Reference numeral 543 denotes a buffer control unit, which controls to read out a packet stored in the buffer when an input terminal of a switch connected to each buffer is connected to a desired output terminal.
[0020]
FIG. 10 is a diagram illustrating a configuration of a packet in the network of the reference example. In the figure, N is a node number indicating the node device to which the destination terminal is connected. T is a transmission channel number indicating the transmission channel to which the destination terminal is connected. In other cases, a synchronization signal, an error correction code, and the like are inserted as needed.
[0021]
FIG. 2 shows the internal configuration of the separation insertion units 501 to 508. Reference numeral 201 denotes a header detection unit that detects header information of a packet, reference numerals 202 and 203 denote gates that output or block input signals, reference numeral 204 denotes a selector that outputs one of two input signals, and reference numeral 205 denotes a packet that temporarily outputs a packet. This is a FIFO for storing.
[0022]
The destination information (destination node number N) in the header of the packet input to the separation / insertion unit is detected by the header detection unit 201, and the gates 202 and 203 are opened and closed based on this. That is, when the detected node number N matches the own node number stored in the header detection unit in advance, the gate 203 is opened and the gate 202 is closed, and the packet is output to the terminal. If the node number N does not match the own node number, the gate 202 is opened and the gate 203 is closed, and the packet is output to the selector 204.
[0023]
On the other hand, the packet transmitted from the terminal is temporarily stored in the FIFO 205, inserted into the packet stream output from the gate 202 via the selector 204, and sent to the buffer unit.
[0024]
FIG. 3 shows the internal configuration of the buffer units 511 to 518. Reference numeral 301 denotes a buffer memory including storage areas 311 to 318 corresponding to respective output terminals of the switch unit 541 and a FIFO memory 304, reference numeral 302 denotes a header detection unit that detects a node number N and a channel number T from a packet header. Reference numeral 303 denotes an address counter that supplies a write address to the buffer memory 301. The node number N and the channel number T of the packet input from the separation / insertion unit are detected by the header detection unit 302, and the storage area for storing the packet is determined based on the contents thereof.
[0025]
The header detection unit 302 stores in advance the number of the own node and the number of a node adjacent downstream (referred to as a downstream node number). The header detection unit detects the node number N and the channel number T from the packet input from the separation / insertion unit, and if the node number N matches the downstream node number, the storage area corresponding to the channel number T (storage area 311 to storage area 311). 318) is designated in the address counter 303, and the address counter generates a write address corresponding to the designated address and stores the packet in any storage area in the buffer memory 301. If the node number N does not match the downstream node number, the packet is stored in the FIFO memory 304.
[0026]
FIG. 4 is a connection table showing a connection relationship between each input terminal and each output terminal of the switch unit 541. That is, by sequentially and periodically changing the control address to A1, A2, A3, A4, A5, A6, A7, and A8, the signal input to the input terminal IN1 of the switch unit 541 is connected to OUT1, and then OUT2. , OUT3, OUT4, OUT5, OUT6, OUT7, and OUT8 in this order. At this time, the input terminal IN2 is connected in the order of OUT3, OUT4, OUT5, OUT6, OUT7, OUT8, and OUT1. The same applies to the other input terminals IN3 to IN8.
[0027]
FIG. 11 illustrates a connection relationship according to the connection table in FIG. 4 in a time-series manner. The operation of the switch unit is constituted by eight continuous periods T1, T2, T3, T4, T5, T6, T7, T8. Further, each cycle is divided into Td, which is a reading period from the storage areas 311 to 318, and Tf, which is a reading period from the FIFO memory 304, by a reading operation in the buffer unit. The period of Td and Tf may be determined as appropriate, but here, when there are no more packets to be read from the storage areas 311 to 318, the period shifts to the period of reading Tf from the FIFO memory.
[0028]
FIG. 6 is a configuration example of a communication network using the node devices shown in FIG. 5, in which four node devices 601 to 604 are connected in a ring form by multiplex transmission lines 605 to 608, and each node device has 8 nodes. Eight terminal devices are connected via the sub transmission lines. The terminal devices 611 to 618 correspond to the terminal devices 551 to 558 in FIG. 5, and the same applies to the terminal devices 621 to 628, 631 to 638, 641 to 648.
[0029]
Next, a transmission control method of this network will be described by taking communication from the terminal device 611 to the terminal device 634 as an example. In the header part of the packet transmitted from the terminal device 611, the node device number 634 of the node device to which the terminal device 634 is connected as the node number N and the terminal device 634 as the transmission channel number T The number 4 of the transmission channel connected via the path is set. The packet output from the terminal device 611 is inserted into the packet stream via the sub-transmission path and the separation / insertion unit, and is input to the buffer unit 511 in FIG. The header detector compares the node number N (3 in this case) in the header with the downstream node number (2 in this case). Since the two do not match, the packet is stored in the FIFO memory 304. Since the packet stored in the FIFO memory is read out during any one of the readout periods Tf during the operation periods of T1 to T8 in FIG. 11, the transmission channel used for transmission to the next node is specified. Not done. Here, it is assumed that data is read out during the operation period T8, that is, a period in which the input terminal IN1 and the output terminal OUT2 are connected, and transmitted to the next node 602 via the transmission channel 2. In the node 602, for the packet input to the separation / insertion unit 502 in FIG. 5, the header detection unit compares the node number N (3 in this case) in the header with the own node number (2 in this case), and the two do not match. Therefore, it is input to the buffer unit 512. The buffer unit compares the node number N (3 in this case) in the header with the downstream node number (3 in this case). Since the two match, the storage area corresponding to the transmission channel number T in the header, that is, the channel number 4 ( It is stored in the storage area 314) in FIG. The packet stored in the storage area 314 in the buffer unit 512 is read at the timing when the input terminal IN2 and the output terminal OUT4 are connected, that is, in the operation period T7 in FIG. To reach the next node 603. In the separation / insertion unit of the node 603, the node number N in the header is compared with its own node number. In this case, since both match at 3, the packet is separated by the separation / insertion unit and is the destination via the sub-transmission path. The terminal device 634 is reached.
[0030]
As described above, in the network of this reference example, a packet transmitted from an arbitrary terminal device is relayed at a relay node on the way while changing the transmission channel at random, and the packet is transmitted to the node to which the destination terminal device is connected. In the immediately preceding node, communication between arbitrary terminal devices is performed by switching to the transmission channel to which the destination terminal device is connected.
[0031]
The communication network of the present invention is based on a network such as the above-described reference example, monitors the number of packets stored in each buffer means, detects congestion, and detects congestion. Congestion notification transmitting means for notifying the preceding node device of a transmission channel corresponding to the buffer means in which congestion is detected, congestion notification receiving means for receiving congestion notification from another node device, and congestion notification receiving The congestion control is performed by providing packet transmission control means for suppressing or stopping transmission of a packet to the notified transmission channel based on the congestion notification received by the means.
[0032]
(First embodiment)
A first embodiment of the present invention will be described.
[0033]
FIG. 1 is a configuration diagram of a node device in a network according to the present invention, and shows an example in which terminal devices 151 to 158 are connected to a node device 100 via sub-transmission paths.
[0034]
Reference numerals 121 to 128 and 131 to 138 denote multiplex transmission lines having a plurality of transmission channels, for example, a plurality of (eight in this configuration example) optical fiber transmission lines separated spatially, or one optical transmission line. This is a wavelength division multiplex transmission line using a fiber.
[0035]
Reference numerals 101 to 108 denote separation / insertion units, which detect destination addresses of packets input from the multiplex transmission paths 121 to 128 and, based on the destination addresses, determine whether packets transmitted to the terminals 151 to 158 via the sub transmission paths are determined. , Into packets input to the buffer units 111 to 118, and also inserts packets transmitted from the terminal into the packet stream input from the multiplex transmission path. In addition, when a control packet described later is input from the multiplex transmission path, at least one separation / insertion unit (101 in FIG. 1) separates the control packet and outputs the control packet to the control packet reception unit 147.
[0036]
Reference numerals 111 to 118 denote buffer units, which temporarily store packets output from the separation / insertion unit in a storage area corresponding to each output terminal of the switch unit 141 or a FIFO memory connected to an arbitrary output terminal of the switch unit. Has functions.
[0037]
Reference numeral 141 denotes a switch unit, which connects the input terminals IN1 to IN8 to any output terminals OUT1 to OUT8 under the control of the switch control unit 142, thereby transmitting a packet to any one of the multiplex transmission lines 131 to 138. When using a plurality of spatially separated optical fiber transmission lines as a multiplex transmission line, the switch unit 541 is configured using a space switch or the like.
[0038]
Reference numeral 142 denotes a switch control unit, which controls the switch unit 141 according to the connection table shown in FIG. FIG. 4 is a connection table showing a connection relationship between each input terminal and each output terminal of the switch unit 141, as in the above-described conventional example. By sequentially and periodically changing the control address to A1, A2, A3, A4, A5, A6, A7, and A8, the signal input to the input terminal IN1 of the switch unit 541 is connected to OUT1, and then OUT2, OUT3 , OUT4, OUT5, OUT6, OUT7, and OUT8 in this order. At this time, the input terminal IN2 is connected in the order of OUT3, OUT4, OUT5, OUT6, OUT7, OUT8, and OUT1. The same applies to the other input terminals IN3 to IN8.
[0039]
Reference numeral 143 denotes a buffer control unit, which stores packets stored in the storage areas 311 to 318 in the buffer unit and the FIFO memory 304 when an input terminal of a switch connected to each buffer is connected to a desired output terminal. Is read. When the control packet receiving unit 147 is notified of the occurrence of congestion in a subsequent node device, the control packet receiving unit 147 stops reading from the FIFO memory when connected to the output terminal corresponding to the target transmission channel. When the reception unit notifies that the congestion has been resolved, the reading from the FIFO memory is started to return to the normal state.
[0040]
Reference numeral 144 denotes a congestion detection unit that monitors the number of packets stored in the FIFO memories in the buffer units 111 to 118 and, when the number of packets exceeds a predetermined threshold 1, determines the occurrence of congestion in the buffer unit. The number is notified to the control packet transmitting unit 145 together with the number, and if the number falls below the threshold value 2 (<threshold value 1), the control packet transmitting unit is notified of the elimination of congestion together with the number of the buffer unit.
[0041]
Reference numeral 145 is a control packet transmitting unit. The control packet is a packet that is exchanged between node devices periodically or as needed for the purpose of network maintenance and operation. In this embodiment, the control packet is used as means for notifying congestion. When receiving the notification of the occurrence of congestion or the elimination of congestion from the congestion detection unit 144, the control packet transmitting unit generates a control packet addressed to the preceding node device, and corresponds to the code indicating the occurrence of congestion or the elimination of congestion, and the code corresponding to the target buffer unit. Write the transmission channel number in the data section. The generated control packet is output to the switch unit 141 via the selector 146, and transmitted to the preceding node device.
[0042]
Reference numeral 147 denotes a control packet receiving unit that receives the control packet addressed to the own node separated by the separation / insertion unit 101. If the received control packet is a control packet for notifying the occurrence of congestion or the elimination of congestion, the control packet receiving unit notifies the buffer control unit 143 to that effect together with the target transmission channel number.
[0043]
FIG. 8 is a diagram illustrating a configuration of a packet in the network according to the present embodiment. In the figure, C is a control bit, and indicates whether or not the packet is a control packet. N is a node number indicating the node device to which the destination terminal is connected. T is a transmission channel number indicating the transmission channel to which the destination terminal is connected. In other cases, a synchronization signal, an error correction code, and the like are inserted as needed. If the packet is a control packet for notifying congestion information, a code indicating occurrence or resolution of congestion and a number indicating a target transmission channel are entered in the data portion.
[0044]
FIG. 7 shows an internal configuration of the separation / insertion unit 101. Reference numeral 701 denotes a header detection unit that detects header information of a packet, reference numerals 702, 703, and 706 denote gates that output or block input signals, reference numeral 704 denotes a selector that outputs one of two input signals, and reference numeral 705 denotes a packet. Is a FIFO for temporarily storing.
[0045]
The information (control bits C and destination node number N) in the header of the packet input to the separation / insertion unit 101 is detected by the header detection unit 701, and each gate is opened / closed based on the information.
[0046]
First, when the control bit C is detected, if the node number N matches the own node number, the gates 702 and 703 are closed, the gate 706 is opened, and the packet is output to the control packet receiving unit. If the node number N does not match the own node number, the gate 702 is opened and the gates 703 and 706 are closed, and the packet is output to the selector 704.
[0047]
When the control bit C is not detected, if the node number N matches the own node number, the gate 703 is opened and the gates 702 and 706 are closed to output the packet to the terminal. If the node number N does not match the own node number, the gate 702 is opened and the gates 703 and 706 are closed, and the packet is output to the selector 704.
[0048]
On the other hand, the packet transmitted from the terminal is temporarily stored in the FIFO 705, inserted into the packet stream output from the gate 702 via the selector 704, and sent to the buffer unit.
[0049]
Since the separation / insertion units 102 to 108 do not have a control packet separation function, the configuration of FIG. 7 may be the same as the separation / insertion unit 101, or the configuration of FIG. 2 described in the reference example.
[0050]
FIG. 3 shows the internal configuration of the buffer units 111 to 118. Reference numeral 301 denotes a buffer memory including storage areas 311 to 318 corresponding to respective output terminals of the switch unit 541 and a FIFO memory 304, reference numeral 302 denotes a header detection unit that detects a node number N and a channel number T from a packet header. Reference numeral 303 denotes an address counter that supplies a write address to the buffer memory 301. The node number N and the channel number T of the packet input from the separation / insertion unit are detected by the header detection unit 302, and the storage area for storing the packet is determined based on the contents thereof.
[0051]
The header detection unit 302 stores in advance the number of its own node and the number of a node adjacent downstream (referred to as a downstream node number). The header detection unit detects the node number N and the channel number T from the packet input from the separation / insertion unit, and if the node number N matches the downstream node number, the storage area corresponding to the channel number T (storage area 311 to storage area 311). 318) is designated in the address counter 303, and the address counter generates a write address corresponding to the designated address and stores the packet in any storage area in the buffer memory 301. If the node number N does not match the downstream node number, the packet is stored in the FIFO memory 304.
[0052]
However, in the buffer unit 111, the header detection unit also detects the control bit C, and when this is detected, regardless of the node number N and the channel and the channel number T, the packet is stored in the storage area 311 corresponding to the channel number 1. Remember. That is, the control packet is different from the normal packet and is transmitted to the destination node device via only the first transmission path.
[0053]
FIG. 11 illustrates a connection relationship according to the connection table in FIG. 4 in a time-series manner. The operation of the switch unit is constituted by eight continuous periods T1, T2, T3, T4, T5, T6, T7, T8. Further, each cycle is divided into Td, which is a reading period from the storage areas 311 to 318, and Tf, which is a reading period from the FIFO memory 304, by a reading operation in the buffer unit. As long as there are packets to be read in the storage areas 311 to 189, the reading period Td from the storage areas 311 to 318 continues, and thereafter, the process shifts to the reading period Tf from the FIFO memory. However, when the congestion in the subsequent node device is notified, the reading from the FIFO memory is stopped only in the cycle connected to the output terminal corresponding to the target transmission channel under the control of the buffer control unit 143. You.
[0054]
Next, the operation of the congestion control in the present embodiment will be described. Now, it is assumed that the number of packets stored in the FIFO memory (304 in FIG. 3) in the buffer unit 3 (103 in FIG. 1) of a certain node exceeds a predetermined threshold value 1. The congestion detecting unit 144 detects this, notifies the control packet transmitting unit 145 that congestion has occurred in the buffer unit 3, and the control packet transmitting unit 145 generates a control packet addressed to the preceding-stage node device, and detects the occurrence of congestion. The code to be written and the number 3 of the transmission channel corresponding to the target buffer unit 3 are written in the data unit. The generated control packet is output to the switch unit 141 via the selector 146, and transmitted to the preceding node device.
[0055]
The control packet arriving at the preceding node device is separated by the separating / inserting unit 101 and sent to the control packet receiving unit 147. The control packet receiving unit analyzes the data portion of the control packet and notifies the buffer control unit 143 of the occurrence of congestion on the transmission channel 3. The buffer control unit controls the reading from the buffer units 101 to 108 in the switch unit such that the reading from the FIFO memory 304 is stopped only in a cycle in which each input terminal is connected to the output terminal 3.
[0056]
FIG. 9 shows the state of the buffer reading control at this time in a time-series manner. At the input terminal 1, reading from the FIFO memory is stopped in a period T7 connected to the output terminal 3. Similarly, T8 at the input end 2, T1 at the input end 3, T2 at the input end 4, T3 at the input end 5, T4 at the input end 6, T5 at the input end 7, and T5 at the input end 8 from the FIFO memory in the period of T6. Reading is stopped. As a result, only transmission of packets passing through the buffer unit 3 of the next-stage node in which congestion has occurred is stopped, and packets passing through other buffer units are transmitted as usual. This does not occur, and a decrease in throughput during back pressure control can be avoided.
[0057]
The reason why the reading from the storage areas 311 to 318 is not stopped is that the packets in the storage areas 311 to 318 are packets addressed to the terminal device connected to the next-stage node. This is because they are separated and sent to the destination terminal device and do not affect the congestion in the buffer unit.
[0058]
When the number of packets stored in the FIFO memory of the congestion notification source falls below a predetermined threshold value 2 (<threshold value 1), the congestion detection unit detects this, notifies the control packet transmission unit, and notifies the control packet transmission unit. Generates a control packet in which a code indicating the release of congestion is written, and sends it to the preceding node device. The control packet is received by the control packet receiving unit of the preceding node device in the same manner as in the case of the congestion occurrence notification, and the buffer control unit cancels the reading stop from the FIFO memory and returns to the normal state.
[0059]
【The invention's effect】
As described above, according to the communication network and the transmission control method of the present invention, even when congestion occurs, the location (transmission channel) where the congestion has occurred is notified to the preceding node device. By suppressing or stopping only the transmission of a packet passing through the location where the error occurs, it is possible to avoid a decrease in throughput due to congestion control.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a node device according to the present invention.
FIG. 2 is a diagram showing an internal configuration of a separation / insertion unit of the node device of the reference example.
FIG. 3 is a diagram showing an internal configuration of a buffer unit of the node device.
FIG. 4 is a diagram showing a control pattern of a switch unit.
FIG. 5 is a diagram illustrating a configuration of a node device according to a reference example.
FIG. 6 is a diagram showing a configuration of a network.
FIG. 7 is a diagram showing an internal configuration of a separation / insertion unit of the node device according to the present invention.
FIG. 8 is a diagram showing a configuration of a packet used in the network of the present invention.
FIG. 9 is a diagram showing buffer read control at the time of congestion in the present invention.
FIG. 10 is a diagram illustrating a configuration of a packet used in a network of a reference example.
FIG. 11 is a diagram temporally showing a control pattern of a switch unit.
[Explanation of symbols]
100,500,601-604 node device
121-128, 131-138, 521-528, 531-538, 605-608
151 to 158, 551 to 558, 611 to 618, 621 to 628, 631 to 638, 641 to 648 Terminal device
101-108, 501-508 Separation and insertion section
111-118, 511-518, 301 Buffer unit
141,541 switch unit
142,542 switch control unit
143,543 Buffer control unit
144 Congestion Detector
145 control packet transmission unit
147 control packet receiving unit
302 Header detector
303 address counter
304 FIFO memory
311 to 318 Storage memory

Claims (4)

A communication network for connecting a plurality of node devices with a plurality of transmission channels and transmitting packets,
The node device has buffer means for temporarily storing a received packet in correspondence with each of the transmission channels,
Congestion detection means for monitoring the number of packets stored in each of the buffer means, and detecting the occurrence of congestion,
When the congestion is detected by the congestion detection means, a transmission channel corresponding to the buffer means in which the congestion is detected, a congestion notification transmitting means for notifying the preceding node device,
Congestion notification receiving means for receiving a congestion notification from another node device,
A communication network, comprising: packet transmission control means for suppressing or stopping transmission of a packet to the notified transmission channel based on the congestion notification received by the congestion notification receiving means. In claim 1,
Based on the congestion notification received by the congestion notification receiving means, suppresses or stops the transmission of a packet transmitted to the next and subsequent node devices via the next-stage node device to the notified transmission channel. A communication network comprising packet transmission control means. A communication network for connecting a plurality of node devices with a plurality of transmission channels and transmitting packets,
The node device has buffer means for temporarily storing a received packet in correspondence with each of the transmission channels,
Switch means for sequentially changing the transmission channels for outputting the packets stored in the respective buffer means in a predetermined order and simultaneously so that packets from the respective buffer means are output to different transmission channels,
Congestion detection means for monitoring the number of packets stored in each of the buffer means, and detecting the occurrence of congestion,
When the congestion is detected by the congestion detection means, a transmission channel corresponding to the buffer means in which the congestion is detected, a congestion notification transmitting means for notifying the preceding node device,
Congestion notification receiving means for receiving a congestion notification from another node device,
Based on the congestion notification received by the congestion notification receiving means, while the output transmission channel of each of the buffer means is set to the notified transmission channel, transmission of packets stored in the buffer means is suppressed. Alternatively, a communication network having packet transmission control means for stopping. In claim 3,
Based on the congestion notification received by the congestion notification receiving means, the period in which the output transmission channel of each buffer means is set to the notified transmission channel is the next one of the packets stored in the buffer means. A communication network, comprising: packet transmission control means for suppressing or stopping transmission of a packet transmitted to a subsequent node device via a node device of a stage.

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