JPS6324742A - Suppressing system for complexity in packet switching - Google Patents

Abstract

PURPOSE:To suppress an input to a packet switching set from a terminal, by adding a bit of information to represent a complicated state on a packet passing the packet switching set, when the packet switching set falls in the complicated state. CONSTITUTION:A complexity detecting part 1, and a suppression information adding part 2 are provided at a node, and a bit of suppression information is added on the packet in the reverse direction of the direction of communication in which the complicated state is generated at the node, then it is sent out. Since a logic link is not terminated, and a bit of information is added on a communication packet using the logic link, it is possible to send rapidly the bit of suppression information due to the complexity generated on the midvay of the logic link, to a terminating part. Also, by utilizing the fact that a transmission confirmation packet is transferred in the reverse direction of the direction of the communication along a communication logic link, the transmission confirmation packet of a junction line in the reverse direction corresponding to the junction line in the complicated, state can be captured. In this way, it is possible to inform the bit of suppression information due to the generation of the complexity automatically, to all of the equipments on a traffic generating terminal side performing the communication via a complicated junction line.

Description

[Detailed Description of the Invention] [Table of Contents] Overview Industrial Application Fields Prior Art (Figures 14 to 18) Problems to be Solved by the Invention Examples of Means and Actions for Solving the Problems (1) First embodiment (Figs. 1 to 6) (2) Second embodiment (Figs. 7 to 13) Effects of the invention [Summary] When a certain packet switch becomes congested in a packet communication network , information indicating a congestion state is added to packets passing through the packet switch, and the terminal instructs the packet switch to suppress input.

[Industrial application field]

The present invention relates to a method for suppressing packet switching congestion, and in particular, when a packet switch is in a congested state, input restrictions are applied to the packet switch to release the congested state.

Conventional packet switching networks, as shown in Figure 14, transmit data at both ends of each transmission line (or subscriber line).
Link control (DLC) is provided to detect errors in received data and retransmit packets with errors. Further, the CPU of each node checks the exchange information of the packet and determines its transfer destination. As described above, since the CPU intervenes and processes each time the packet passes through the transmission path, there is a limit to the speedup of such packet exchange by the CPU.

For this reason, there is a high-speed packet switching network as shown in FIG. 15(a). Here, each node is provided with a hardware switch, and data link control is provided only between terminals. However, at the receiving end of each transmission path, only packet errors are detected, and packets with errors are discarded. The packet switch in the node is shown in FIG.
), exchange is performed using only the transmission header added to the packet type. By simplifying the transmission header, the packet switch can operate at high speed using hardware.

[Prior Art] In high-speed packet communication networks, it is necessary to reduce the packet transfer time at relay nodes in order to speed up packet transfer within a premises. For this reason, at the relay node, the minimum operations necessary for packet transfer, such as changing packet routes and logical numbers, are performed, and logical links as communication management sections such as packet generation and destruction are performed on the information sending side. In many cases, a so-called in-network linter method is adopted in which one section is between the information reception example and the information reception example.

, In the M4 linter method, packet transfer between the information sending side and the information receiving side can be performed quickly, but since a direct logical link is set up between the relay node in the middle of the link and the information sending side and the information receiving side, In between, the control logical link is relayed in several stages for transmission.

However, if congestion is detected at a relay node along the route,
It is necessary to quickly and accurately transfer the traffic transmission regulation information to the information transmitting side that is generating the congested traffic, suppress the transmission of new packets, and eliminate the congestion.

Now, in a high-speed packet network as shown in FIG. 16, an outline of the operation will be explained when communication is performed from transmitting/receiving terminal A to B using the in-network one-linter method. The in-network 1-linter method mentioned here means that when a communication request occurs between two transmitting and receiving terminals, communication is performed by connecting the two transmitting and receiving terminals with one communication logical link, and when one communication is completed, this This is to cancel the exclusive logical link.In order to set up and cancel this ill-trusted logical link, it is necessary to exchange control information between each node, but there is a control logical link between each adjacent node. is always set, and necessary control information is transmitted to each note via this control logical link.

In FIG. 16, when a connection request is generated from terminal A to B, the connection request information is transmitted to node l, which analyzes this connection request information and connects to node 4 where node B is accommodated. Select one of the routes, for example trunk line 1, and use the control logical link of trunk line l to connect to node 2.
The communication logical link setting request information from the notebook '1 to the node 4 is transferred to the node '1. Node 2 selects trunk line 2, which is the connection route from trunk line 1 to node 4, and sets a logical link for communication from terminal A to terminal B between relay vA1 and vA2, and also connects the control logic of trunk line 2. Relay line 2 using the link
Transfers communication logical link setting request information from node 4 to node 3. Node 3 also connects trunk line 2 like node 2.
A logical communication link is set between terminals A and 3, and communication logical link setting request information is transferred from terminal A to terminal B via trunk line 3. After confirming that communication to terminal B is possible on node 4, the first day of middle school! To set up a logical link for communication from line 3 to terminal day, confirm the completion of the logical link for communication from terminal A to day, and set up a logical link for communication in the opposite direction from terminal day to terminal day, trunk line 3 is set. The logical link completion information from terminal A to B and from terminal B to A are sent to node 3 via
Transfer logical link setting request information for communication to. Similarly, nodes 2 and 1 set up a logical link for communication from terminal B to terminal 8, and when this is completed, communication enable information is transferred from node 1 to terminal A, and communication from terminal B to terminal B begins. Ru.

FIG. 17 shows the logical link setting status during communication between the terminals A and B, with only related nodes selected, and each node has a transmission path switching unit and a CPU that controls it.
The physical transmission path shown by the solid line includes a control link shown by a dotted line and a communication logical link shown by a dashed line.

FIG. 18 shows a typical sequence from the start of communication (3) to the end of communication between terminals A and B, where CR is a call request packet, CN is an incoming call packet, and CA is a communication from terminal B to A. Incoming call acceptance packet, CC is connection completion packet, D is data packet from terminal A to B, D' is terminal B
A data delivery confirmation packet from to A, CQ is a recovery request packet based on a disconnection instruction due to completion of communication, CI is a disconnection instruction packet to the terminal, and CF is a disconnection sent when terminal B disconnects based on this disconnection instruction packet. This is a confirmation packet, and when this packet reaches 8 from terminal B, the disconnection is complete. Of these, D and D' use logical links for communication, and the others use logical links for control.

[Problems to be Solved by the Invention] By the way, if communication between other transmitting and receiving terminals increases during communication between terminals A and B, and node 3 detects a congestion state on trunk line 3, that is, when node 3 When a predetermined amount of packets are internally held in the buffer memory for sending packets to trunk line 3, the originating side/terminal (terminal A and other terminals) communicating via trunk line 3 include)
Therefore, it is necessary to reduce the traffic that passes through the line 3 during which communication traffic regulation information is being sent.

To do this, it is first necessary to extract all communication logical links that use the trunk line 3 as an outgoing route at the node 3, and to identify the originating terminal corresponding to this link. It is then necessary to send traffic regulation information to these originating terminals.

If we consider the case where terminal A sends the traffic regulation terminal ta as a terminal that corresponds to the originating terminal, it is first necessary to send the information to node l where terminal A is accommodated.

In this case, since no direct logical link is set between node 3 and node 1, A
A traffic control information packet is first sent to node 2, and node 2 analyzes the content of the acid traffic control information packet, determines that the information is for node 1, where the terminal is accommodated, and forwards it to node 1. Then, traffic regulation information is transmitted to terminal A at node 1.

However, since the 111 trust logical link passes through node 2 at high speed, a large amount of communication information arrives at node 3 until traffic regulation begins, resulting in overflow of communication information in node 3's buffer memory and deterioration of communication quality. do. Another problem is that in order to prevent overflow, it is necessary to provide a large amount of buffer memory for each trunk line.

An object of the present invention is to provide a packet switching congestion suppression method to solve this problem.

[Means for solving problems]

In order to achieve this object, the present invention provides a congestion e! detection unit 1 and a suppression information addition unit 2 in a node as shown in FIG. Suppression information is added to packets in the opposite direction to the direction of communication being sent.

[Effect]

The present invention adds information to communication packets using a logical link without terminating the logical link.
Suppression information due to congestion that occurs in the middle of a logical link can be quickly sent to the end of the logical link, and it also takes advantage of the fact that delivery confirmation packets are transferred in the opposite direction to the communication direction along the logical link for communication. By capturing the delivery confirmation packet of the trunk line in the opposite direction corresponding to the trunk line in the congested state, congestion automatically occurs on all traffic generating terminals communicating via the congested trunk line. can transmit suppression information in a short time.

〔Example〕

(1) First Embodiment An embodiment of the present invention will be explained based on FIGS. 2 to 6.

FIG. 2 shows an example of a node configuration to which the present invention is applied, and is shown corresponding to the linode 3, and FIG. 3 shows a data packet from terminal A to terminal B, corresponding to FIGS. 17 and 18. (
Figure 4 shows the flow of the data packet delivery confirmation packet from terminal B to terminal A, and
The figure shows a case where the route (from terminal A to terminal B) with trunk line 3 as the outgoing route at node 3 is congested and the accumulated data in buffer memory M2 of packets sent to trunk line 3 exceeds a certain amount. The explanatory diagram, FIG. 6, shows an example of a sequence chart when the congestion state shown in FIG. 5 occurs during communication between terminals A and B.

In the figure, 10 is a node control device corresponding to the control unit in FIG. 1, 11 is a signal transfer circuit connected between common lotus BUs, 12 to I4 are trunk line compatible devices, and 15 is a terminal compatible device. . The trunk line compatible device 12 includes a signal receiving circuit R2, a signal sending circuit S, a buffer memory 'JM+, Mz, a signal combining circuit C1, a control circuit C0NT, etc., and the trunk line compatible devices 13 and 14 are also equipped with the trunk line compatible device 12. It is configured in the same way.

The terminal compatible device 15 also has a signal receiving circuit R.
', signal output path S', buffer memory M1, Mz
, (No. 8 coupling circuit C1 control circuit C0NT', etc.) are provided. Buffer memories M3 and M2 are also connected to the node control device IO.

Next, when nodes 1 to 4 according to the present invention are connected as shown in FIG. 12 and terminals A and B perform packet 7) communication, node 3 sends data packets from terminal A to terminal B (
(Communication information) flow, ■Flow of data packet delivery confirmation packet from terminal B to A, ■When the route using trunk line 3 as the outgoing route (direction from terminal to B) becomes congested, respectively. explain.

2) Figure 3 shows the flow of data packets from terminal A to terminal B. First, a message consisting of a flag F for packet identification, an address TH, data D, and a flag F is transmitted from the trunk line 2 to the trunk line corresponding device 12 of the node 3 via the node L and node 2 connected to the terminal A. When a packet in the format shown in FIG. 15(b) arrives, the signal receiving circuit R extracts address 8 and data D and stores them in the buffer memory M1. The signal transfer circuit 11 connected to the common bus BU takes out the address A and data D from the buffer memory M1 of this trunk line compatible device 12, and determines that the information is to be transferred to the trunk line 3 from the contents of TH. 'lI separate. As a result, the signal transfer circuit 11 transfers this address TH and data D to the panzer memory M2 of the trunk line corresponding device 14 corresponding to the trunk 1 trunk 3. The signal sending circuit S of the trunk line correspondence device 14 takes out the address TH and data D from the panzer memory M2, adds flags F and F for packet identification, formats them into a packet format, and sends them to the middle mvi 13.

■ Figure 4 shows data packet delivery confirmation from terminal B to A and the flow of the packet. The address and data are T'H' and D', respectively, and the transfer route is from the trunk line 3 to the trunk line 2, contrary to the case (2) above, as it is the same as the case (2) above, so the details will be omitted. .

■ Figure 7 shows the route from the node to trunk line 3 (
This shows a case where the terminal A (direction from terminal A to B) is in a congested state and the accumulated data in the panzer memory M2 of packets sent to the trunk line 3 in the trunk line correspondence device 14 exceeds a certain amount.

When the accumulated data in buffer memory M2 exceeds a certain amount,
Control circuit C0NT is activated. As a result, the control circuit C
0NT creates traffic regulation information for the originating terminal and transfers it to the signal coupling circuit C. When the information sent from the buffer memory M is data D' for data delivery stone recognition, the signal coupling circuit C adds the traffic regulation information D'' following the data D', and combines these D' and D-
are collectively transferred to the common bus BU together with the address TH' as one data signal. When this information is transmitted to the signal transfer circuit 11 connected to the common bus, the signal transfer circuit 11 determines from the contents of the address TH' that the information should be transferred to the trunk line 2 designated by the address TH'. As a result, the signal transfer circuit 11 transfers the data D' and the traffic regulation information D'' as a series of data to the trunk line corresponding device 12 corresponding to the trunk line 2. Thereafter, this traffic regulation information D'' is transferred together with the data D'. and is transferred via node 2 to the originating node l. This traffic regulation information is analyzed by a terminal compatible device (configured similarly to the terminal compatible device 15 illustrated in FIG. 2) corresponding to terminal A in node 1, and traffic transmission regulation from terminal A is carried out. be exposed.

Note that FIG. 6 shows an example of a sequence chart when a congestion state occurs. In FIG. 6, the shaded area represents the congestion period of the trunk line 3. That is, in the first normal state, terminal A sends data D to B, and in response, terminal B
When terminal A returns data D' confirming data packet delivery to terminal A, terminal A immediately sends the next data D to terminal A.

By the way, when the output route of trunk line 3 becomes congested, terminal B
Data D′ of the data packet sent from 8 to 8
The data (D'+D'') to which the traffic restriction information has been added is delivered to terminal A. When the terminal receives this traffic restriction notification, it sends the next data D after a period of time has elapsed. If the congestion state is cleared after receiving the traffic regulation information three times in this way, terminal A receives the data D' acknowledging the data packet bi from terminal B again. Immediately after that, the next data D
will be sent.

Note that there may be various types of communication using the trunk line 3 as an outgoing route, such as communication to the terminal of node l (not shown), terminals of other nodes, etc., in addition to the communication to the terminal of node l. Since all delivery confirmation packets of data packets pass through the ingress side of the trunk line 3, by simply adding the traffic regulation information t[LD'' mechanically to the ingress delivery confirmation packet, none of the above The same effect as that of the communication between terminals A and B described above occurs also in communication.

In addition, by providing an area for writing traffic regulation information in advance in the delivery confirmation packet, and writing the traffic regulation information in the traffic regulation writing area instead of adding the above-mentioned traffic regulation information + [D], delivery can be confirmed. The data length of the confirmation packet may be constant before and after writing the traffic regulation information.

Here, the congestion state of the trunk line is a state in which transmission requests exceeding the allowable transmission capacity of the trunk line have occurred, and can therefore be dealt with by lowering the transmission request rate. For this reason, there are various methods for achieving 1-rahinoku control, such as a method of interrupting information transmission for a certain period of time, and a method of reducing the information transmission ratio (focus rate) to a constant rate.

Further, instead of using a packet delivery confirmation packet, a traffic control packet is sent from the receiving side to the sending side at regular intervals or irregularly, and the delivery confirmation bucket described in E is sent to this packet.

Congestion control can also be performed for communications that do not use delivery confirmation packets by performing the same control as in the above. In this case, the relay node may be provided with a function of adding or changing specific data bits to the traffic control packet, and the data bits may be added or changed depending on the congestion state.

(2) Second Embodiment A conventional method for preventing packet congestion is window flow control. However, this is a method of limiting the number of packets staying in the packet network to a certain number or less for each call, so if a large number of calls are accommodated in the packet switching network, the Packets may accidentally concentrate on a packet switch, causing congestion. Therefore, a method is needed to detect the occurrence of congestion and notify the terminal.

A conventional method for this purpose is to use choke packets. In this method, a node that detects congestion sends a congestion notification to all terminals considered to be the source using choke packets. By the way, in the conventional choke packet method, even if a node that detects congestion sends a choke packet, which is a congestion notification, to a terminal that is considered to be the source of congestion, if a node adjacent to that node is congested, the choke packet is sent to the terminal that is considered to be the source of the congestion. Packets may be dropped. Therefore, congestion notification may not be thorough. Therefore, as explained below, priority packets are required.

A second embodiment of the present invention will be described based on FIGS. 7 to 13.

In the second embodiment, a packet indicating the congestion state is prepared separately from a data packet, and the transmission of the packet indicating the congestion state is given priority over the transmission of the data bucket. It is.

FIG. 7 is a schematic configuration diagram of a node, in which (a) is a schematic diagram when one terminal is connected, and (b) is an explanation of the packet switch (PSW), transmitter, and receiver. Figure, 8th
Figure 9 shows the configuration of a packet switch, Figure 9 shows the principle of sending congestion information into a congestion monitoring packet, Figure 10 explains the packet format, Figure 11 shows the configuration of the transmission section of the transmission line interface, Figure 12 The figure shows the configuration of the terminal interface, and FIG. 13 is an explanatory diagram of the transmission state of congestion monitoring packets and normal data packets.

In this example, terminal A connected to node 10 and node 11
A case will be described in which data is transferred between terminals 8 connected to the terminal 8.

Each node has a packet switch (PSW) that examines the packet header and determines the transmission route to the destination.
20, a terminal interface 21 for controlling transmission and reception of data with a terminal, and a transmission line interface 22 for transmitting and receiving data with a transmission line.

As shown in FIG. 7(b), when not only a terminal but also a plurality of transmission lines 1 and 2 are connected to a node, a transmission line interface for the transmission line 1 including a sending ε section 31 and a receiving section 41; A transmission path interface including a transmitting section 32 and a receiving section 42 for the transmission path 2, and a transmitting section 3 for the terminal.
A terminal interface comprising a receiver 3 and a receiver 43 will be provided. The packet switch 20 includes a receiving section 41
43, receives the received packet from the selected receiver, and transmits the transmitter 3.
Outputs the transmitter address that selects one of 1 to 33 and sends the transmitted packet to the selected transmitter, or determines whether the transmitted packet is a normal data packet or a monitoring packet (CMP) with congestion information. Accordingly, it outputs transmission priority and receives transmission unit congestion information.

The details of the configuration of this packet switch 20 are shown in FIG. As shown in FIG. 8, the packet switch 20 includes a receiver address generator 51 that outputs a receiver address, a new logical channel number (new LC
a mapping RAM 52 that outputs the transmission unit address for bucket transmission, and outputs the transmission priority;
a timing adjustment shift register 53; an LCN reassignment unit 54 that reassigns a logical channel number (LCN) to a new LCN;
A congestion information addition unit 55 that adds line axis information, and a switch that switches between using the output of the reception unit address generation unit 51 as the transmission unit address or outputting the transmission unit address for packet transmission output from the MS2 to the mapping R. SW
It is equipped with I.

When receiving a packet, the switch SWI is connected to the y side and the output of the receiver address generator 51 is output as the transmitter address. As a result, at the time of reception, when the receiving section 41 is selected, the transmitting section 31 that has the same interface as the receiving section 41, that is, the transmitting section 31 that sends the packet in the opposite direction to the receiving section 41, is selected, and the receiving section 42 is selected. When the receiving section 43 selects, the transmitting section 32 is selected at the same time, and when the receiving section 43 selects, the transmitting section 33 is selected at the same time. Depending on the selection of the transmitters 31 to 33, check the status of the transmitter,
If the transmitter is in a congestion state, line axis information of the transmitter is transmitted, so if the transmitter in the opposite direction to the receiver is in the line axis state, this can be added to the transmission packet. And when actually transmitting it, switch SW1
is connected to the y side to output the packet transmission transmission address outputted from the mapping RAM 52 based on the address of the header of the received packet, and the transmission packet is sent to this address.

The principle of setting this line axis information in the line axis monitoring packet lift will be explained with reference to FIG. In the present invention, line axis information is included in the line axis monitoring packet and sent separately from the data packet. That is, as shown by the dotted line in FIG. 9 and the solid line in FIG. 13, the congestion monitoring bucket is transmitted from the terminal interface to the opposite terminal interface. As shown in Figure 9,
The congestion monitoring packet is transmitted to the receiving unit 4n of the transmission line interface n for the transmission line N, and the packet switch 20
, the packet switch 20 checks the line axis state of the transmitting section 3n of the same interface, that is, the congestion state of the transmitting section in the direction opposite to the receiving side. At this time, if the transmitter 3n for the transmission path N is in the line axis state, that is, if the amount of packets waiting to be transmitted through the transmission path is greater than a predetermined amount, the packet switch 20 transmits the congestion information as shown in FIG. The adding unit 55 sets the line axis information in the line axis monitoring packet and transfers it to the destination transmitting unit 3m.

The terminal interface that has thus received this line axis monitoring packet from the transmitter 3m of the transmission line interface m via the transmission line M restricts entry to the terminal if it indicates a congestion state.

By the way, since the line axis monitoring packet is transmitted and received as a priority packet between terminal interfaces, it is possible to reliably send congestion information to the terminal interface without being affected by the line axis.

As shown in Figure 10, a packet is formed by a logical channel number LCN, an attribute indicating whether the packet is a normal data packet or a line axis monitoring packet, and a data section. Line axis information is entered in this data section.

Further, the terminal ink face 21 shown in FIG. 7(a) includes, as shown in FIG. 12, a terminal compatible HD LC unit 61, a partner station compatible transmitting/receiving unit 62, a congestion monitoring packet transmitting/receiving unit 63,
It is equipped with a packet mixing/distributing section 64 and the like. Here, the terminal compatible HDLC unit 61 executes a link level packet transfer procedure with the terminal, and the partner station compatible transmitting/receiving unit 62 functions as a partner station compatible transmitting/receiving unit in the terminal interface that accommodates the terminal of the communication partner. Data packets are sent and received between the two. Any link level procedure may be used at this point, such as denying the error. In addition, the line axis monitoring packet transmitter 63 repeatedly exchanges line axis monitoring buckets with the line axis monitoring packet transmitting/receiving unit 13 in the terminal interface accommodating the terminal of the communication partner at regular intervals, and also transmits the received line axis monitoring packet. If the line axis information is sent, a congestion notification is sent to the terminal compatible HDLC unit 61.

The terminal compatible HDLC unit 61 thereby provides HD
Sends an LC reception disable command to restrict input. In addition, the packet mixer/distributor 64 classifies the packets transmitted via the transmission path into normal data packets and congestion monitoring packets, and sends the data packet 7) to the partner station corresponding transmitter/receiver 62, and also classifies the packets transmitted via the transmission path into congestion monitoring packets. Ordinary data packets sent to the congestion monitoring bucket transmission/reception unit 63, or conversely, regular data packets sent from the partner station corresponding transmission/reception unit 62, or constant cycles sent from the line axis monitoring packet transmission/reception unit 63! I.J.
The congestion monitoring packet of I is sent to the transmission path.

As detailed in FIG.
rst out) Backup memory 71 and normal side FIF
O buffer memory 72, 73 and changeover switch SW, 2,
Equipped with SW3. From the packet switch (PSW) to ij! The translated transmitting unit controls the switch SW2 according to the transmission priority to transmit the FIFO buffer memory 7 on the priority side.
1 or the normal side FIFO buffer memory 72. Furthermore, when sending a packet to the transmission path, the switch SW3 is operated to send out the packet in the FIFO buffer memory 71 on the priority side more quickly. The normal side has two FIF○ buffer memories'7
2.73 is cascaded and has a corrupted configuration, and when the first backup memory, the FIFO buffer memory 73 on the transmission line, becomes full, the congestion lB! The information becomes rlJ,
[Pakeso] switch (PSW) is notified of the line axis state. The FIF○ buffer memory 72 on the rear packet switch side is provided to provide a margin against congestion.

Next, the operation of the second embodiment will be explained.

Now, as shown in FIG. 13, when a data packet is transmitted from terminal A to B, the linode 10.
A case will be described in which a bus passing through 20.30.4o and 50 is set, and a line axis state occurs in the node 30 during data packet transmission.

■ When data is transmitted from a terminal to terminal B, when the bus is set, a line axis monitoring packet ( CMP) is transmitted at regular intervals.

When this line axis monitoring packet is transmitted to the packet switch (PSW) of the node 20, the mapping RAM 5
2 (see FIG. 8) is accessed with the logical address number LCN and attribute as the lower address and the output of the receiver address generator 51 as the upper address. In the case of a congestion monitoring packet, the switch SWI is connected to the X side to output the same address as that of the receiving section as the address of the transmitting section, and as described above, the line axis information of the transmitting section in the opposite direction to the congestion monitoring bucket is obtained. Next, the switch SWI is connected to the y side to output the address of the transmission part of the line axis monitoring packet, and the width Φ deviation monitoring packet is transmitted to the timing adjustment shift register 53, and the LCM replacement part 53 updates it. The logical address number is changed, the packet transmission priority is set to the priority side, and the packet is transferred to the transmitter. Also, based on the transmission priority signal, as shown in FIG.
3 to the transmission path, and is sequentially transmitted to the next node.

(2) A data packet is then created in the node 10 based on the data input from the terminal A, and when this is transmitted to the node 20, the mapping RAM 52 is accessed in the same manner as in (2) above. Since the packet received at this time is a normal data packet, the switch SWI is connected to the y side and outputs the address of the transmitter to which the data packet is sent, and also sends the packet to the shift register for timing adjustment.
3, the LCN reassignment unit 53 reassigns it to a new logical address number, sets the packet transmission priority to normal, and transfers it to the transmitter without adding line axis information. At this time, since the transmission priority is in the normal state, for example "0", the switch SW2 is connected to the normal FIF○ buffer 72 side, so this data packet is temporarily stored in the FIFO buffer 73 via the FIFO buffer 72. Senodo and Sui.

When the switch SW3 is connected to the FIF○ buffer 71114, it is sent out onto the transmission path and is sequentially transmitted to the next node.

■ By the way, in FIG. 11, the number of data packets sent to the FIFO buffer memory 73 is large.
When the FIFO buffer memory 73 becomes full, the line change state is entered, and the full flag indicating this becomes IIJ, and a line axis thudding indicating the line change state is output. Now, in the node 30 of FIG. 13, if such a line axis condition occurs in the transmission path from terminal A' to B', this node 3
As described above, line axis information indicating the congestion state is added by the line axis information adding unit 55 in FIG. .

That is, this is added to the line switching monitoring packet sent from the terminal to A, and transmitted to the terminal interface of the node 10.

■ In the terminal interface of this node 10, the 12th
As shown in the figure, the line change monitoring packet transmitting/receiving unit 63 checks this, recognizes that a line axis condition has occurred, and reports this to the terminal compatible HDLC unit 61. Based on this, the terminal compatible HDLC unit 61 outputs a major restriction signal instructing the terminal A' to suppress input data, so that the input data from the terminal A' is -
Stop. Based on this, the transmission of data packets passing through node 3o is also stopped.

■ If the number of data packets set in the FIFO buffer memory 73 is reduced by suppressing the data packets to the transmitter of the node 30 in this way and the line axis information is released, then the line passing through this Since the information indicating the existence of the line switching state is no longer included in the line switching monitoring packet, the line axis monitoring packet transmitting/receiving unit 63
However, the line axis depression occurrence signal is canceled. As a result, the major restriction signal outputted by the terminal compatible HDLC section 61 is also canceled, so terminal A outputs the input data again.
The data packet is sent out again from the node 10.

〔Effect of the invention〕

According to the present invention, effective line switching control can be performed because the traffic information generated on the relay lines in the network can be accurately transmitted to the related traffic sources. In addition, line change control is easy,
When the number of accumulated data in the buffer memory of an outbound route exceeds a certain value, traffic regulation information is added to the delivery probability L2 packet passing through the corresponding inbound route, which enables high-speed hardware control. High safety against failures due to distributed control that can be handled by the trunk line support section.

Furthermore, line switching monitoring packets are transferred as priority packets, so congestion is reduced! Since the information quickly arrives at the sending terminal interface, it is possible to quickly restrict input to the terminal.

Moreover, since this priority packet, the line switching monitoring packet, is sent out at regular intervals, it is possible for the line switching information to reach the transmitting terminal interface reliably and quickly, making line switching of the packet switching network faster. Solution) 11 can be done.

[Brief explanation of the drawing]

Fig. 1 is a detailed explanatory diagram of the present invention, Fig. 2 is a configuration diagram of a first embodiment of the present invention, Fig. 3 is a first explanatory diagram of a packet transfer route, and Fig. 4 is a first explanatory diagram of a packet transfer route. 2, FIG. 5 is an explanatory diagram of the line axis state, FIG. 6 is an example of a sequence chart during line axis control, FIG. 7 is a schematic diagram of a node in the second embodiment of the present invention, and FIG. 8 is a diagram of a packet switch. Fig. 9 is a diagram of the principle of how line axis information is sent to a line change monitoring packet, Fig. 10 is a diagram explaining the packet format, Fig. 11 is a block diagram of the transmission section of the transmission line interface, Fig. 13 is a diagram explaining the transmission state of line switching monitoring packets and normal data packets, 14 [ffl is a conventional packet switching network, FIG. 15 is a high-speed packet switching network, and FIG. 16 is a packet switching network. ) FIG. 17 is an explanatory diagram of a logical link setting situation, and FIG. 18 is an example of a sequence chart. 10--Node control device 11--Signal transfer circuit

Claims (5)

[Claims] (1) In a packet communication network that includes a terminal and multiple relay nodes, a logical link is set up between the sender and the receiver across one or more relay nodes, and data packets are sent along the same route from the sender to the receiver. In a packet communication system that transfers a packet through a packet transfer route, there is a congestion state reporting means (CONT) that reports the congestion state on the packet transfer route, and an additional means (C) that adds a signal indicating the packet congestion state.
When a congestion state occurs at any point on the packet transfer route, it instructs the transmitting terminal of the congestion state to the packet to be transmitted, and thereby prevents the terminal from transmitting input data. A packet switching congestion suppression method characterized by suppressing packet switching congestion. (2) The packet switching congestion suppression method according to claim 1, wherein the packet is a delivery confirmation packet. (3) By sending a packet from the receiving side to the sending side periodically or irregularly, and adding or changing specific data bits to this packet when relaying this packet at a relay node. The packet switching congestion suppression method according to claim 1, characterized in that the congestion state is reported. (4) The packet switching congestion suppression method according to claim 1, characterized in that a congestion monitoring packet is provided outside the data packet, and this congestion monitoring packet is given a priority. (5) Claims 1 and 4 characterized in that congestion monitoring packets are sent out at regular intervals.
Packet switching congestion suppression method described in Section 2.