JPH0314345A - Congestion control system in packet exchange network - Google Patents

Abstract

PURPOSE:To prevent the occurrence of blocking or deadlock in burst communication without exerting influence upon the communication of an immediate system by constituting each packet input part so as to stop an output from a corresponding buffer based upon congestion information obtained from a congestion informing bus. CONSTITUTION:Respective packet input parts 11, 14 are provided with respective storage volume monitoring means 112, 142 for monitoring a storage volume of a transmission line corresponding buffer 114, 144 and for instructing input regulation to the packet input parts 11, 14 when the storage volume exceeds a prescribed value. On the other hand, respective packet output parts 12, 15 are provided with respective input regulation informing means 122, 152 and the packet output part 12 in a transmission line corresponding part 10 is provided with a congestion monitoring means 123 for monitoring the storage volume of a burst system output buffer and at the time of detecting congestion, stopping packet output from the corresponding transmission line corresponding buffer in the packet input part 11 of another transmission line corresponding part 10 in the same node through a congestion informing bus provided for mutually informing the congested state. Consequently the occurrence of blocking or deadlock in burst communication can be prevented.

Description

[Detailed Description of the Invention] [1 Already Required] It has a plurality of transmission path compatible parts connected to each of the transmission paths and a plurality of end uncompatible parts connected to each of the terminals, and each corresponding,
Regarding a packet-switched network configured by packet-switched nodes equipped with a switching section that transfers packets between sections, it is possible to perform bronching for burst communication without affecting real-time communication when congestion occurs. The aim is to provide a congestion control method for the packet 1 switching network that can prevent the occurrence of packet 1 switching and droning. Each packet input section includes a hander analysis means for analyzing the batch hander, an immediate communication buffer for real-time packets, and a transmission line provided for each destination transmission line for burst-type communication packets to other notebooks. A corresponding buffer and a terminal-compatible huffer addressed to the terminal of the own node are provided, and each packet output unit is provided with an immediate-type output huffer for immediate-type packets and a burst-type output buffer for packets of berth 1/system communication, Congestion monitoring means is provided in the packet output section of each transmission path corresponding section to output a congestion notification to a congestion notification bus provided to notify the congestion status between each corresponding section when congestion of the burst type output huffer is detected. The packet input unit is configured to stop outputting from the corresponding buffer in response to a congestion notification from the congestion notification bus.

[Industrial Application Field 1] The present invention has a plurality of transmission line compatible parts connected to each of the transmission lines, and a plurality of end uncompatible parts connected to each of the terminals,
A packet exchange 10 configured by a packet switching node equipped with a switch unit that transfers page numbers 1 and 1 between each corresponding unit.
Regarding Am.

In general, in packet-switched NI4, if the traffic from a terminal or an adjacent node fluctuates significantly, or if a detour is performed due to a failure in a node or transmission path, congestion may occur as more packets than the node can handle are concentrated on one node. be.

If such a state continues for a long time, the delay time will increase and the first failure will occur in the notebook, and not only will it be impossible to guarantee the communication quality for each communication, but it will also cause a decrease in network throughput. Become.

Several methods have been used in the past to minimize such performance deterioration, but the conventional methods have various drawbacks, and it is desired to realize an efficient congestion control method.

[Conventional technology] FIG. 9 is an explanatory diagram of a conventional example.

In FIG. 9, A. represents the simultaneous input restriction method, and 8.
represents the heart call input restriction method.

When nodes 1 to 4 making up the switching network are provided, each node transfers the input packet to the transmission path to the destination node or to its own terminal.

Conventional example A. In this method, if congestion occurs on node 2 as a result of large fluctuations in traffic from terminals or neighboring nodes, or as a result of a detour being performed due to a failure in the node or transmission path, all terminals connected to that node or adjacent node l. Congestion notification is performed for 3.4 as shown in the figure.

Then, the terminal or notebook that receives this notification stops outputting the packet 1 directed to this width comparison node 2.

In the conventional method B, when a width comparison occurs in node 2, the virtual call (called VC) that causes
Detect. A virtual call refers to a logical channel specified at the time of setting up a call in packet switching. Once set up, transfer control is performed using a virtual call identification number (VCI), and the baggage of a specific virtual call number is , is found to be the cause of congestion, it notifies neighboring nodes or terminals of input restrictions for that particular heart call. The adjacent node or terminal that receives this notification stops transmitting to node 2 only the packets having the restricted virtual call number. Input is not restricted for packets of other virtual calls.

[Problem to be solved by the invention] A. In this method, simultaneous input is restricted without being aware of the content of each communication, so control is slow and recovery from congestion is fast. However, due to simultaneous input restriction, other nodes that were not originally the cause of the problem may also have their output restricted (hereinafter referred to as pro-noking), and adjacent nodes that have received congestion notifications may become congested, causing them to send packets to each other. There is a drawback that the network throughput may be lowered because there is a possibility of falling into a state where mutual transfer is no longer possible and recovery from congestion is not possible (hereinafter referred to as dendronk).

Conventional example B. Since this method restricts input for each virtual call, there is no bronching or de7}ronok, and the optimal effect can be obtained as a network loop note, but it is necessary to notify all virtual calls that are subject to restriction. As a result, the length of the notification packet 1 becomes long, and the control to stop outputting only the packets of Herchalk calls that are subject to the restriction at terminals and nodes that receive input restriction notifications becomes complicated, and software control becomes difficult. This method had the disadvantage that it required intervention and was not suitable for high-speed control.

Furthermore, it centrally accommodates instant communication such as voice and image communication, which requires an extremely short time from when a packet is generated until it reaches the other party, and burst communication such as data communication. In multimedia packet networks, such bronching, dendronking, and complex software control impair the quality of delay time, especially for real-time communications. This made it difficult to implement.

SUMMARY OF THE INVENTION An object of the present invention is to provide a congestion control method for a packet-switched network that can prevent the occurrence of bronching and dendronok in burst communications without affecting real-time communications when congestion occurs. .

[Means for solving the problem] A first basic configuration diagram of the present invention is shown in FIG. 1, and a second basic configuration diagram is shown in FIG. 2.

Figure 1 shows the configuration of one packet exchange node in a packet switching network. A transmission path corresponding section provided for one transmission path l among the plurality of transmission path corresponding sections, 1l is a packet input section in the transmission path corresponding section, 12 is a packet output section also in the transmission path corresponding section, l3 is an end unsupported section connected to one terminal among the end unsupported sections provided for a plurality of terminals accommodated in this node; 14 is a packet input section in the end unsupported section; 15 is a packet output section; 16 is a congestion notification bus; 17 is a switch unit that transfers input packets to a desired output side; 18
represents transmission lines 1 to N, and 19 represents a terminal interface.

Each packet input section 11.14 has a transmission line compatible buffer 1.
Storage amount monitoring means 112 and 142 are provided which monitor the storage amount of the 14 144 and instruct the input unit 11 to restrict input when the storage amount exceeds a predetermined value. In addition, each packet output unit is provided with an input restriction notification unit 1 that sends an input restriction notification based on an input restriction instruction from the storage amount monitoring unit.
22, 152 are provided, and the packet output section of the transmission path 2 corresponding section is provided with a congestion notification bus provided to monitor the accumulated amount of burst output huffers and notify each other of the congestion status when congestion is detected. A congestion monitoring means 123 is provided for stopping the packet output from the corresponding transmission line corresponding buffer of the packet input section of the other transmission line corresponding section of the same notebook.

FIG. 2 shows a partially modified structure of the packet output section of the transmission path corresponding section in FIG. 1, and the other parts are the same as in FIG. 1.

In FIG. 2, 20 represents a transmission path corresponding section, 21 a packet input section, 22 a backup 1/output section, 26 a width comparison notification bus, 27 a switch section, and 28 a transmission path. In addition, the symbols 20 to 29 (23 to 25, 29 are omitted) are lO in Fig.
Corresponds to ~19.

The packet input section 21 of the transmission line correspondence section 20 in FIG.
It is similar to the packet input unit 11 in the figure, but the adjacent node (
Burst type output buffers 225l to 225-M (total of M transmission paths provided by adjacent nodes) corresponding to the transmission paths provided by the other node connected to the opposite side of the transmission path to which each transmission path corresponding unit connects. The difference is that it has the following features:

The present invention monitors from which input section communication packets that cause congestion are input in a packet switching node, and selects burst communication that causes congestion in order from the input path with the largest number of packets and inputs. This method restricts the input of only packets to reduce the occurrence of blowing and dendlock, and avoids a drop in network throughput.

[Operations] In FIG. 1, the Pakken 1 exchange node has a transmission path compatible section to (only one shown) provided corresponding to the transmission path it accommodates, and an end uncompatible section 13 (one shown) connected to the terminal. (only shown) and the transfer section 17 that transfers buckets between each transmission path corresponding section and each corresponding section of the end uncoupled section.

The procedure of the operation in FIG. 1 will be explained below in terms of sections.

(1) Hander analysis means 1ll 141 of the packet input section 11.14 of each transmission path corresponding section IO and end unsupported section l3
analyzes the header of packets input from the corresponding transmission path or terminal interface, and identifies burst communication packets such as real-time packet data communication such as voice and image communication, and packets destined for the terminal of the own node. death,
Immediate packets are transferred to the immediate communication buffer 113.143.
burst type packets are stored in the transmission path corresponding buffers 114-1 to 114-N for each destination transmission path, and packets destined for the own node are stored in the terminal corresponding buffers 115, 1.
Accumulates to 45.

(2) The switch section 17 transfers the packet input from each buffer of the packet input section of each transmission path compatible section or end unsupported section to the output buffer of the packet output section of the target transmission path compatible section or end unsupported section. .

(3) The width comparison monitoring stage 123 of the packet output section of each transmission line corresponding section 10 monitors the accumulated amount of the burst output buffer, and when the accumulated amount exceeds a certain dark value, the congestion notification bus 16 is used to transmit the data. A congestion notification indicating the path corresponding section (for example, the transmission path corresponding section of transmission path 2) is output.

(4) When the packet input units of all the other transmission line compatible units/end unsupported units (other than the transmission line compatible unit of transmission line 2 in the above example) receive the congestion notification via the congestion notification bus l6, they take action. packet output from the transmission path compatible buffer (in this example, the transmission path compatible buffer addressed to transmission path 2) is stopped.

(5) If the buffer (in the above example, the buffer corresponding to the transmission line addressed to transmission line 2) whose output of packets and notes has been stopped due to (4) above exceeds a certain amount of storage, the corresponding bage and note input section The accumulated amount monitoring stage 112 detects this and instructs the packet output unit to send an input restriction notification. As a result, the corresponding packet output unit transfers the input regulation notification packet to the adjacent node connected to the transmission path corresponding unit using the input regulation notification stage 122.

(6) When the accumulated amount of the burst output j buffer of the congested transmission path support section becomes below a certain value due to the operations (3) to (5) above, the above (3) to (5) The reverse control is performed, and the input restriction notification stage 122 instructs the adjacent node to transfer the input restriction release packet.

(7) When the adjacent node determines that the received packet is an input regulation notification packet by the packet input section's hander decoding means (ill of the adjacent node), it controls the packet output section and outputs it from the burst type output buffer. Stop reading. Also, if you receive an input restriction cancellation notification packet, will the same restriction apply? Reading from the burst output buffer is restarted by ffn.

In this way, by controlling the packet switching node with the basic configuration shown in FIG. Input regulation can be performed on only burst communication packets starting from the input path with the largest number of inputs. This not only reduces the occurrence of pronokink and denodronok, but also f! Since the batch 1 of the I1 time-based communication is not affected by congestion, it becomes easy to realize the multimedia packet kj4 that centrally accommodates the instant-time and non-identical 1υ1-based communication.

Next, we will explain the operation in Figure 2 with a configuration different from that in Figure 1.
C: I'll explain.

Similarly to (1) in the explanation of the operation in FIG. 1 above, packets input to each packet input section are stored in respective target buffers.

Next, in (2), the switch unit transfers the packet input from the buffer of each packet input unit to a predetermined output buffer. At this time, the burst packet l outputted to the packet output section of the transmission path correspondence section is stored in each output buffer 1-M provided corresponding to the transmission path in the adjacent node.
(225 in Figure 2).

(3) of the action explanation in Figure 1. Similarly to (4), when the congestion monitoring means 224 in the packet output section detects congestion, the congestion notification bus 26 notifies the packet input section of each transmission path corresponding section to send the packet to the output section of the packet node 1 where congestion has occurred. stop sending. In addition, (5) and (6) above
Similarly, when the accumulated amount of the buffer corresponding to the transmission path whose output is stopped at the packet input section exceeds a certain dark value, the packet output section is given an instruction to send an input restriction notification, thereby preventing congestion from neighboring nodes. transmits an input restriction notification packet containing information on the transmission path where the error occurred.

(7) When the adjacent node receives this input regulation notification packet, it controls the packet output unit. That is, this adjacent node is also equipped with an output buffer in its packet output unit corresponding to the transmission path provided by the adjacent node (No. 1' that generated the input restriction notification), as in FIG. Reading of the burst system output buffer specified by the transmitted transmission line 1117 report is stopped. Therefore, packets are transferred as usual from other output buffers (other output buffers addressed to the node that generated the input restriction notification). In addition, input restriction has been lifted! When receiving ・, reading from the burst output buffer is resumed using the same control.

Note that the input restriction is applied only to packets of burst type communication {S, and the transfer is performed regardless of packet number 1 of real-time type voice/image communication.

[Embodiment] Fig. 3 is a diagram showing the structure of an embodiment of the transmission path corresponding section, Figs. Figure 5 is a diagram of the configuration of the packet output section, Figure 6 is a diagram of the congestion notification bus, Figure 7 is a diagram showing the format of input restriction packets and input restriction release packets. Figure 8 is Figure 4. FIG. 6 is a diagram showing a specific example of the operation shown in FIG. 5;

FIG. 3 corresponds to the structure of an embodiment of the transmission path corresponding section of the basic configuration diagram shown in FIG.

30 in FIG. 3 is a transmission path corresponding section, 3l is a packet input section,
33 is a packet output section.

The operations shown in FIG. 3 will be explained in the following order of operations.

■Packets arriving from the transmission path are sent to the packet input section 31
The signal is input to the delay buffer 310 and the hender portion is notched to the hesodar resist 311. Until this packet is output from the delayed Banoff γ 310, the transfer destination of the packet 1- is determined by referring to the header analysis table 312 based on the value stored in the header L/register 311, and the selector 3l3 is via the immediate communication buffer 320,
One of the transmission path compatible buffers 1 to 3 (321 to 323) and the edge uncompatible buffer 324 is selected.

(2) The packet output from the delay buffer 310 drives one of the write counters 318 selected under the control of the selector 313 and is accumulated in a predetermined buffer.

■The suinochi unit (see No. 111al7) scans each buffer of each packet input unit 31 including other transmission line corresponding units (not shown), and if there is a packet l, it scans this into the corresponding packet, 1, output unit. Transfer to 33.

■In the packet output unit 33, if the packet from the suinochi unit is an immediate communication packet, the immediate output buffer 33
9, and if it is the hearth 1 communication bucket 1-, it is input to the berth 1 system output buffer 338 by controlling the snow counter 333.

(2) In the output section 33, the output section 1 of the normal immediate output buffer 339 is given priority and outputted to the transmission line. In this packet output unit 33, a calculation unit 335 provided for the burst output buffer calculates the difference (N time) between the write counter 333 and the read counter 332, and the comparator 336 calculates the difference between the accumulated amount and the congestion +9 difference. If the stored M4 amount is larger than the value set in the value register 334, the predetermined focus (?!
H! Each binoto of the 2 binoto corresponds to each transmission line corresponding part)
Turn on (“1゜゛).

Here, a configuration diagram of an embodiment of the width comparison notification bus will be described using FIG. 6.

In FIG. 6, transmission path corresponding section 1 (61). 2 (6
2)... are shown, and the portions that do not correspond to the ends are not shown.

The width light monitoring means 611 in the transmission path corresponding section 1 (61) is as follows:
This corresponds to a structure for removing congestion from the arithmetic unit 335 and comparator 336 provided for the burst system output 8 of the packet 1/output unit 33 in FIG. Then, when a congestion state occurs in the congestion monitoring means 611 of the transmission path corresponding section 1, the line numbered 1 among the N lines constituting the congestion notification bus is set to on ("1" degree). In this case, this number l
The lines 1 and 2 indicate the connection between the own transmission line corresponding section 1 and the other transmission line corresponding section 2.
3, etc. are supplied to the reading unit of the transmission line compatible buffer 1 (buffer in which Bakken I directed towards the transmission route l is stored) provided in the packet input unit of all the transmission route compatible units, and the data of this number 1 is When the line is turned on, reading b is stopped. Further, when the switch returns from on to off ("0°"), reading resumes again.

■As a result of the above ■, the congestion of the bus I system output buffer of a certain packet output unit is notified to the other packet input unit 31 (actually, another transmission path corresponding unit not shown in FIG. 3) via the congestion notification bus. When the packet input section) detects this, the operation of the read counter 319 of the corresponding transmission path corresponding huffer (one of 321 to 323) is stopped, and packet transfer to the switch section is stopped. As a result, only instant communication packets are input to the reduced width packet output unit, so that the burst output buffer recovers from the reduced width state. On the other hand, the storage capacity of the transmission path compatible buffer that has stopped packet transfer gradually increases after packets arrive from the transmission path.

(2) In the packet input section 3l, the M. mmD is obtained by calculating the difference (B-A) between the value B of the write counter 318 and the value 8 of the read counter 319, and the difference D obtained by 11 is stored in the storage monitoring register 314.
It is compared with the value C set in . If the result of the comparison shows that it is COD, it is assumed that there is a congestion state, and OR gate 3
The congestion notification control unit 331 of the corresponding packet output unit 33 is notified via l7.

When the congestion notification system 1 section 331 receives the notification from ■, it interrupts the continuous output of normal packets from ■ and transfers the input restriction notification packet.

The format of the input restriction notification packet transferred at this time is shown in Figure 7B. Shown below. That is, Bakeno1 header (LCN
:8Q unreasonable) and packet type identifier (indicated by C)
In the two bits representing the packet type identifier, "01" is set as an input restriction notification packet, and an input restriction release packet "lO", which will be described later, is set.

■When the packet input unit of the adjacent node (not shown, but in the following explanation, 31 in FIG. 3 corresponds to this) receives the above-mentioned input restriction notification packet, it recognizes this in the header analysis table 312. do. Then, the continuous output counter 33 of the burst system output bar of the corresponding packet output unit 33 from the Henda analysis table line 3120
2 is generated, and the output of burst type communication packets is regulated.

[Phase] On the other hand, in the transmission path corresponding section of the node where the congestion occurred, the packet output section (the packet output section that turned on the focus of the congestion notification bus in ■) 33 that caused the congestion}/system output As a result of the above-mentioned (2), the buffer 1 is no longer inputted from the input section (17 in FIG. 1), so only output is executed and the buffer gradually recovers from the I1 cross state. By detecting this with the comparator 336, the predetermined binoto of the previously output congestion notification path (16 in FIG. 1) is turned on or off.

■When the other packet input unit 3l detects that the predetermined focus of this width comparison notification bus is turned off, it restarts the readout counter 319 of the transmission path corresponding buffer, which had previously stopped continuous output due to the bint-on. It starts up and starts transferring packets to the switch section.

@Arithmetic unit 315 provided for each transmission line corresponding buffer of the packet input unit 3l. The ratio 1.2 unit 316 monitors the accumulated amount in the same way as in the case (2) above, and when it detects that the output of Pakeno 1 has resumed, it notifies the congestion notification control unit 331 of the corresponding packet output unit 33.

(2) When the shark notification control unit 331 receives the @ notification, it interrupts the normal packet/1 read operation of (2) and transfers the input restriction release packet (Formanoto is shown in FIG. 7A).

[Phase] When the packet input unit of the adjacent node receives the above @ input restriction release packet from the node where the congestion has occurred, it is recognized in the header analysis table 312 and the read counter 33 of the corresponding packet output unit 33 is
Start 2 for 11 yen and restart packet output.

The numerical values set in the congestion value register 334 in the operation (2) above and the volume monitoring register 314 in the operation (2) above can be freely changed according to the non-work design and usage conditions. , This makes it possible to freely change the frequency of input restriction notifications to adjacent nodes. Furthermore, if the settings of the congestion value register and the accumulation monitoring register in all packet input sections are the same, the input regulation for adjacent nodes will be limited to jll (with a large number of input packets).
It is clear that this will be done.

The configuration of the end unsupported section has substantially the same function as the transmission line compatible section, with the only difference being that the other party to be connected is a terminal instead of the other party's notebook. The configuration diagram has been omitted.

With the configuration of the embodiment shown in FIG. 3, if a certain transmission path corresponding section becomes congested, the packet switching notebook is provided? When congestion occurs for the burst-type packet 1 on a specific transmission path in the iM transmission path, among the Haas 1-based packets from adjacent nodes headed for that node, the packets are directed to the specific transmission path where the width steepness has occurred. Only the output of the burst panorama can be regulated.

Other embodiments of the transmission path corresponding section shown in FIGS. 4 and 5 have an embodiment configuration corresponding to the second basic J/, k diagram shown in FIG.

The structure of the packet input section 41 shown in FIG. 4 is the same as that of the packet input section 3L in the configuration shown in FIG. 3, and a description of each part will be omitted. Then, the bucket output section 43 shown in FIG.
The structure is partially different from that of the packet output section shown in FIG.

That is, in FIG. 5, the structure of the packet output unit 43 is the congestion notification system 11l1 unit 43l. It is similar to the packet output section in Fig. 3 in that it includes a selector 437, an immediate output buffer 440, etc., but in this structure, the transmission line corresponding section l to which this packet output section belongs (one transmission line is connected A number of bust system output buffers 1 (438) and burst system output buffers 2 (439) are provided corresponding to the transmission lines provided in the node 1 on the other side of the node 1 (assumed to be 1), and the read output counters 432 and 2 (439) are provided respectively. Write counter 433 congestion threshold register 4371, arithmetic unit 435 and comparator 4
It is equipped with 36.

The operation of the transmission path corresponding section in FIGS. 4 and 5 will be explained with emphasis on the points that differ from the operation in FIG. 3.

The operations from 1 to 2 in FIG. 3 are the same as the operations from 1 to 2 in FIG. 3 until a packet is input from the transmission path to the packet input section 4i in FIG. Subsequently, operation ``■'', which is different from operation ``■'' in FIG. 3, is executed.

■“In the packet output unit, the bucket, 1- from the switch unit is loaded into the immediate output buffer 440, and if the packet is destined for the terminal of an adjacent node, it is loaded into the mizui output buffer 441. On the other hand, the hearth 1. If it is a packet for system communication, the burst system output buffers 1 and 2 (in this example, the adjacent node has two destinations other than this transmission path) correspond to the output transmission path at the adjacent node (Kawate node of this transmission path correspondence section). Assume that there is a transmission path), input a write counter according to the destination of the packet with the control ?ffll L.

■ Each burst output buffer 4 of the output unit 43
The operator 435 corresponding to 38.439 calculates the difference (M product) between the writing counter 433 and the reading output counter 432, and the comparator 436 calculates the value of the congestion threshold register 434 and the ratio Φ.
2, and if the increase in volume is larger, turn on the specified bino 1 of the 1st tomb notification bus.

■When the other input section of the server 1 detects from the congestion notification bus that a certain berth 1/system output 8/faka has been input, it stops the proverb counter of the corresponding transmission path buffer and sends it to the input section. 1. Stop the transfer.

On the other hand, the amount of storage in the transmission path corresponding buffer of the packet input section that is accompanied by packet transfer increases each time a packet arrives from the transmission path.

■゜In the packet input section 4l, the congestion state is detected by the arithmetic unit/comparator provided for each transmission path corresponding buffer in the same way as the operation ■ in Fig. 3 above, and the congestion state is detected by the operation in the above ■゜. If there is a buffer corresponding to the transmission line whose output has stopped due to a signal from the steep notification bus, the comparator notifies the congestion status to the congestion notification control section 431 of the packet output section 43. In this case, information indicating which transmission line corresponding bus is congested is also added.

(2) When the congestion notification control unit 431 receives the notification (2) above, it interrupts the continuous output control of the normal packet 71 and transfers all input restriction packets.

The format number 1 of the input restriction notification package 1 transferred in this case is shown in FIG. 7B. That is, the above-mentioned A. Same as 1
It has a packet header (LCN: 3Qfri channel) and a packet Jm-specific identifier (indicated by C), and further includes information on "burst output buffer number".

■゜When the packet 71/input section of the adjacent node, which is the other side of the above-mentioned transmission line correspondence section, receives the input restriction packet marked -12, it identifies it in the header analysis table,
To the other party's note that generated the input restriction packet
・From the packet output unit that outputs, stop the read count for the Haas 1 output buffer corresponding to the identified "burst output buffer number", and output the burst communication packet headed for the transmission path number. to regulate. In this case, the continuous output from other burst-type output buffers that do not have input restrictions directed toward the congested transmission path does not stop.

[Phase]゜φ14 When the compared berth 1/system output Banoff γ recovers from the wide shark state due to the above-mentioned (2), the corresponding comparator turns off the predetermined focus of the congestion notification bus.

When another bagant input unit detects a change in the congestion bus of 0゛ above [phase]゜, the corresponding transmission path illusion response bus restarts.

@゛When the arithmetic unit/comparator provided for each transmission line corresponding buffer in the packet input section detects that congestion has been released, it notifies the congestion notification control section in the packet output section.

``The width comparison notification control section transfers the input restriction release packet in response to this. However, the format shown in FIG. 7B is used.

0゛When this is received at the packet input section of the adjacent node,
Transfer from the corresponding packet output unit's Hearth I/system output banff 1 is resumed.

Figure 8 is similar to Figure 4 above. A specific example of operation according to the structure shown in FIG. 5 will be shown and summarized below.

Nodes A to D are provided as a packet switching network, and node B is provided with transmission line support units 1 to 3 corresponding to transmission lines 1 to 3, respectively (the end unsupported units are omitted from the illustration), and It is assumed that a configuration is provided in which the packet transfer between the transmission path corresponding units is selectively controlled by the unit.

The packet output section of the transmission line corresponding section l (corresponding section with transmission line l) of node B has the transmission line ■. ■0 transmission dew 'cJ Q hzo λ compatible. E7, -Yu. A system output buffer is provided. When congestion occurs in one of the output buffers, for example, the burst output buffer, the binoto (first bino l-) corresponding to the transmission line l of the width comparison notification bus is turned on and notification a is generated. Then, the transmission in which the packet to be transferred to the transmission path 1 (the transmission path where the congestion occurred) of each packet input section in the other transmission path correspondence section 2.3 is performed via the width comparison notification bus. When the path pair L is reached, the output operation of C and F is stopped (see ■゜ above).

In the transmission line support units 2 and 3 of node B, the amount of accumulation in the transmission line support buffer of the packet input unit whose output operation has stopped increases, so when the value exceeds a certain amount, the amount stored in the transmission line support buffer of the packet input unit whose output operation has stopped increases. , instructs to send an input restriction notice (see ■゜ above).

At this time, it indicates that packet transfer destined for the transmission path (2) is congested.

As a result, the input regulation notification Pakeno 1 is directed to the transmission path correspondence sections 2 and 3 connected to the transmission paths 2 and 3 from the other transmission path correspondence section 23 of the no-FB to the transmission path 1. This input restriction notification is sent to other nodes A facing transmission paths 3 and 2, respectively.
, D. To explain only about node A, the packet input unit of the transmission path support unit 3 installed in node A recognizes that it is an input restriction notification, and at the same time, node B is congested with packets destined for transmission path 1. is identified. Among the multiple burst output buffers provided in the transmission line support section 3 of Note A (in this case, corresponding to the number of transmission lines provided in adjacent node B, excluding the transmission line to which the node itself is connected). , stops the output operation of the berth 1 system output buffer that accumulates packets addressed to transmission line 1.

As a result, the packet output unit of the transmission line support unit 3 of node A stops forwarding packets addressed to the transmission line I of node B, and the packet output unit of the transmission line support unit 3 of node B outputs packets for which input restriction has been lifted. The state will be maintained until it is dispatched. On the other hand, for burst type packets addressed to the transmission path 2 that are transferred from the node IA to the node B via the transmission path 3, the transfer operation is performed even during this period.

[Effects of the Invention] According to the present invention, in a Pakken exchange network, when the transmission line correspondence unit provided in the exchange node becomes congested, the input line with the largest number of inputs (the transmission line correspondence unit It is possible to restrict the input of only the hearth 1 to the communication terminal I in order from the terminal unsupported section PAKEN 1 input section).

This makes it possible to reduce the occurrence of prosoking and denodrosoking, and since packets of immediate communication unrelated to congestion are not affected by congestion, immediate and asynchronous (burst) communication can be centrally accommodated. It becomes possible to realize a multimedia packet network.

In addition, according to the present invention, by widening the output huffer corresponding to the transmission path provided in the adjacent node in the packet 1/output section of the transmission path corresponding section, congestion occurs on a specific transmission path in the adjacent node, thereby preventing access control. When a notification is received, packet input to the specific transmission path can be regulated in advance by a node adjacent to the node where congestion has occurred, and efficient transmission can be realized.

[Brief explanation of drawings]

Fig. 1 is a basic block diagram of the present invention, Fig. 2 is a second basic block diagram of the present invention, Fig. 3 is a block diagram of an embodiment of the transmission path corresponding section, Figs. Fig. 5 shows the structure of another embodiment of the transmission path corresponding section, Fig. 4 shows the structure of the packet input section, Fig. 5 shows the structure of the packet output section, and Fig. 6 shows the structure of the congestion notification bus. 7 is a diagram showing the format of an input restriction packet and an input restriction release packet, FIG. 8 is a diagram showing a concrete example of the operation of FIGS. 4 and 5, and FIG. 9 is a diagram showing a conventional example. This is an example horizontal command map. In FIG. 1, lO: Transmission line support unit 11: Baganoto input unit of transmission line support unit 12: Packet output unit of transmission line support unit l3: End unsupported unit 14; Packet input unit of end unsupported unit l5: S Unsupported part output unit l6: Congestion notification bus l7; Switch unit 18: Transmission line l9; Terminal interface

Claims (4)

[Claims] (1) Packet switching that has a plurality of transmission path compatible parts connected to each transmission path and a plurality of end unsupported parts connected to each terminal, and a switch part that transfers packets between each compatible part. In a packet switching network constituted by nodes, each transmission path/end unsupported section (10, 13) is provided with a packet input section (11, 14) and a packet output section (12, 15), and each packet input section ( 11, 14) are header analysis means (111, 141) for analyzing packet headers, and immediate communication buffers (113, 143) for immediate packets.
), transmission path compatible buffers (114, 14) provided for each destination transmission path for packets of burst communication to other nodes.
4) and the end-unsupported buffer (11
5, 145), and each packet output unit (12, 15) has an immediate output buffer (125, 154) for immediate packets and a burst output buffer (124) for burst communication packets.
, 153), and when congestion of the burst type output buffer is detected in the packet output unit (12) of each transmission path corresponding unit, the congestion notification bus (16) provided to notify the congestion status between each corresponding unit is transmitted. A congestion monitoring means (123) for outputting a congestion notification is provided, and each of the packet input units (11, 14) stops outputting from the corresponding buffer in response to a congestion notification from the congestion notification bus. Congestion control method in packet-switched networks. (2) In the congestion control method for a packet switching network according to claim 1, each of the packet input units (11, 14) monitors the amount of storage in the transmission line corresponding buffer, and controls input when the amount of storage exceeds a predetermined value. The storage amount monitoring means (112, 142) provides an instruction to send a notification to a corresponding packet output section, and each of the packet output sections (12, 15) receives an input regulation notification from a corresponding packet input section (11, 14). 1. A congestion control method in a packet-switched network, characterized in that it is provided with an input restriction notification means (122, 152) that transfers an input restriction notification to an adjacent node or terminal in response to a transmission instruction. (3) In the congestion control method in a packet switching network according to claim 2, when the input restriction notification from the adjacent node is detected by the header analysis means (111, 141) of the packet input section, the header analysis means is transmitted to the corresponding packet output section. A congestion control method in a packet switching network characterized by stopping packet output from a burst type output buffer (124, 153). (4) In the congestion control method in a packet switching network according to claim 2, the packet output unit (20-1 to 20-N) of each transmission path corresponding unit (20-1 to
2) is equipped with a burst type output buffer (225) corresponding to each transmission path provided in the adjacent node, and the packet input unit (21 )
1. A congestion control method in a packet switching network, characterized in that when a packet is received at a packet switching network, the packet output section (22) notifies the packet output section (22), and the packet output section (22) stops outputting the corresponding one of the burst type output buffers (225).