JP3508697B2 - Packet switching device and packet switching method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet switching device and a packet switching method for performing packet communication between terminals, and more particularly to a packet switching device and a packet switching method for discarding packets in a congestion state.

[0002]

2. Description of the Related Art In recent years, the use of the Internet has spread rapidly, and along with this, data communication traffic has increased exponentially. This is clear from the fact that it is almost certain that the data communication traffic will exceed the voice communication traffic by the year 2000 in North America and by the year 2002 in Japan.

Under such circumstances, the role of the communication network is changing to how to efficiently transfer the ever-increasing data communication traffic.

For example, in a so-called packet switching system having a switch function such as a router, when a large number of packets are received for a short period of time, information such as packets which cannot be processed due to falling into a so-called congestion state is received. May be discarded.

FIG. 4 shows a block diagram of a general high-speed router as an example of the configuration of a packet switching system according to the prior art. Referring to FIG. 4, the packet switching system includes line units 40 that terminate respective lines 401.
2, a switch unit 403 for switching packets transmitted from each line unit 402, and a switch unit 403.
And a processor 404 for controlling the.

In order to prevent the occurrence of congestion in such a packet switching system, usually, a buffer is arranged in a switch section 403 provided in the packet switching system to temporarily hold a packet and A method is adopted in which packets are exchanged again after being canceled.

However, the occurrence of the congestion state in the packet switching system is related to the switching speed of the switch unit 403 itself and the storage capacity of the buffer, the capacity of the buffer in the packet switching system, and the processing speed. .

However, if a large amount of buffers are provided in the switch unit in order to suppress congestion, the processing speed of the switch unit is reduced, the device of the packet switching system itself is enlarged, and the cost required for production is increased. Will cause.

Therefore, in the prior art, a packet input buffer is provided in each line portion of the packet switching system, and when a large number of packets are temporarily received, the buffer is used to prevent congestion of the switch portion. I was out. Further, when a congestion state is detected in the switch unit 403, a method is adopted in which the input from all the line units 402 is cut off and the data input is stopped until the switch congestion is eliminated.

In the prior art, with such a configuration, the use of a large amount of high-speed buffer required for the switch unit 403 is suppressed, the switch unit is downsized, and the economy is improved.

[0011]

However, in such a system, when a packet exceeding the storage capacity of the buffer provided in each line unit 402 is received, all the line units transfer to the switch unit 403. Since the input of is blocked, not only the line that is actually causing the congestion but also the line that is normally operated is affected.

As a result, the packets of the normally operating line sections 402 are also discarded. Furthermore, in the method according to the conventional technique as described above, a packet with a high priority in the line that causes congestion is also discarded.

Further, as a conventional technique aiming at eliminating congestion occurring on a line, Japanese Patent Laid-Open No. 2616431
There is a packet communication system disclosed in Japanese Patent Publication No.

According to this conventional technique, a packet transmission unit that distributes a transmission packet from the inside of the communication device to a plurality of lines and a packet reception unit that multiplexes the packets received from the plurality of lines and then transmits the packets to the inside of the communication device. In the packet communication system configured to have the packet reception unit, by comparing the number of packets stored in the buffer for storing the received packet with the memory capacity of the buffer, the own station is in a congestion state. If it is determined that the local station is in a congestion state in this determination, the local station processes it by adding information for temporarily limiting the transmission to the local station to the packet. It is configured to reduce the amount of packets to be delivered and eliminate the congestion state.

However, the above-mentioned conventional technique is a means for notifying the restriction to the outside of the own station, and does not eliminate the congestion state in the own station which is currently occurring. Furthermore, in the above-mentioned conventional technique, when a congestion state occurs, the transmission of packets is randomly limited to all the adjacent nodes, so that the transmission and reception of packets to be preferentially processed are also limited. There is a point.

Therefore, the present invention has been made in view of the above problems, and it is necessary to control only the line section that actually causes congestion, thereby making it possible to reduce the cost and size of the packet switching system itself. An object of the present invention is to provide a packet switching device and a packet switching method capable of processing high-priority information while maintaining the above.

[0017]

The Means for Solving the Problems The above object was to achieve
Therefore, the packet switching device according to the present invention receives from the line.
Line receiving means for extracting a packet from the received data
And the packet received by the line receiving means is assigned.
Packet sorting means for sorting according to the assigned priority, and
The number of types of priority assigned to the
Priority of the packets sorted by the sorting means
A plurality of buffering means for temporarily storing each
A package for reading the stored packets from the filing means.
Read-out means and the packet read-out means for a predetermined period
Congestion measuring the number of valid bytes of the packet read in
The packet read by the detecting means and the packet reading means
Means for switching the switch and the switch
If congestion has occurred in the communication means, congestion notification signal
And a congestion notification means for outputting, and the congestion detection means,
As the predetermined threshold, the first threshold having the lowest value and the first threshold
Of the second threshold having a value larger than the threshold of
And a third threshold value with a larger value is set in advance,
When the congestion notification signal is notified by the congestion notification means,
Predetermined number of effective bytes measured by congestion detection means
Of the effective bytes is compared with the threshold of
If the threshold is exceeded, the packet reading means
The buffer that contains the highest priority packet
To allow only packet reading from the logging means
If the result of control and comparison exceeds the second threshold value,
All buffering means for packet reading means
Controls to prohibit the reading of packets from the
If the result of comparison is that the third threshold is exceeded, packet read
Outgoing means stores the lowest priority packet
Packet stored in the buffering means
It is characterized in that it is controlled to be discarded.

A packet switching apparatus according to the present invention
The congestion notification signal is sent to the congestion detection hand via a dedicated control line.
It is characterized in that it is input to the stage.

A packet switching device according to the present invention
Is a multiplexing means for multiplexing a packet and a congestion notification signal.
And the packets and congestion communication multiplexed by the multiplexing means.
A separation means for separating the intelligent signal,
The intelligent signal is sent to the congestion detection means through the common transmission line of the packet.
Is input to.

A packet switching device according to the present invention
Multiple buffering measures are high priority packets.
Buffering means for storing
It is characterized in that it is configured.

A packet switching method according to the present invention
Extracts packets from the data received from the line
Line receiving process and the pattern received in the line receiving process.
Packets that distribute packets according to the assigned priority
Sorting process and number of priority types assigned to packets
The packet is distributed to the buffer provided by the packet distribution process.
Buffer that temporarily stores the dropped packets for each priority
Stored in the ring process and the buffering process
Packet reading step for reading the stored packet, and the packet
Packets read within a specified period in the reading process
Congestion detection process that measures the number of effective bytes of
Switching the packets read in the outgoing process
Switching process and the radiation in the switching process.
Congestion notification process that outputs a congestion notification signal when congestion occurs
And, and the congestion detection step is performed by the congestion notification step.
When the notification signal is notified, the valid bytes measured
Number and the lowest value preset as the predetermined threshold
First threshold value, second threshold value having a value larger than the first threshold value
A value and a third threshold value having a value larger than the second threshold value,
The result of comparison is that the number of valid bytes exceeds the first threshold value.
If it is, the highest priority is given in the packet reading process.
Packets from buffers that contain high packets
It is controlled to allow only reading, and the result of comparison is
If the threshold of 2 is exceeded, the packet reading process
Read packets from all buffers
So that the result of comparison exceeds the third threshold value.
Case, the packet read process has the lowest priority
The packet stored in the buffer that stores the packet
It is characterized in that the ket is controlled so as to be discarded.

A packet switching method according to the present invention
The congestion notification signal is transmitted via a dedicated control line
It is characterized by

A packet switching method according to the present invention
Is a multiplexing step for multiplexing a packet and a congestion notification signal
And the packet and congestion that were multiplexed in the multiplexing step.
A separation step of separating the notification signal, and
The notification signal is transmitted via a common transmission line for packets.
It is characterized by

A packet switching method according to the present invention
Is a buffer that stores high priority packets.
It is characterized in that it has a larger storage capacity
It

[0025]

[0026]

[0027]

[0028]

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION A feature of the present invention is to provide a packet switching device and a packet switching method for switching packets.
A buffer for temporarily accumulating packets received from the line, a congestion detecting means for detecting the occurrence of congestion on the line, and a packet discarding means for discarding the packets accumulated in the buffer are configured. It is characterized by that.

Based on this, the packet switching apparatus and the packet switching method of the present invention will be described in detail below with reference to the drawings.

First Embodiment {Structure of First Embodiment} First, a first embodiment in which the present invention is preferably implemented will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the packet switching device according to the first embodiment.

Referring to FIG. 1, the packet switching apparatus according to the present embodiment has a structure for receiving a packet from a line in each line unit 101, receives data of a connected line, and selects a packet from the received data. A line receiving unit 102 for extracting the packet, a packet allocating unit 103 for allocating the extracted packet according to contents such as a priority and a destination address, and controlling writing to the corresponding buffers 104-1 to 104-n, a packet allocating unit The buffers 104-1 to 10-n for temporarily holding the packets written under the control of the unit 103 and the packet reading unit 10 for controlling the reading of the packets from the buffers 104-1 to 104-n, respectively.
5 and the congestion detection unit 105 for detecting the congestion state of each line unit 101 by monitoring how much packets are transmitted to the switch unit connected to the output stage of each line unit 101.
And a switching interface transmission unit 107 that receives the packet read by the packet reading unit 105 via the congestion detection unit 106 and transfers the packet to the above-described switch unit.
And are configured.

On the other hand, the switching interface receiving unit 110 for receiving the data transmitted from the switch unit to each line unit 101, and the switching interface receiving unit 110 for switching the packet input from the switch unit to the line, A transmission buffer 1 for temporarily holding a transmission packet received by the interface reception unit 110
09, and the line transmission unit 108 for reading out the packet held in the transmission buffer 109 and transmitting it to the line.

Therefore, in the above configuration, the congestion detection unit 106 monitors the packet input to the switching interface transmission unit 107 among the packets received from the lines connected to the respective line units 101. As the monitoring method, for example, the effective number of bytes of the packet read by the packet reading unit 105 and transmitted from the switching interface transmitting unit 107 to the switch unit at the subsequent stage is measured per unit time, and this measurement is performed. From the total number of effective bytes per unit time,
It operates to detect whether or not congestion is occurring in the switch unit.

However, the timing for judging this congestion is
The determination is made at the time when the congestion notification signal for notifying the congestion state generated in the switch unit is input to the congestion detection unit 106, and in this determination, the validity of the packet transmitted to the switch unit measuring as described above is determined. The number of bytes is used to determine whether the own line is the cause of the congestion state. Therefore, the congestion state detected in the switch unit is notified to the congestion detection unit 106 by a congestion notification signal, and based on this congestion notification signal, each congestion detection unit 106 determines whether or not it is the basis of congestion occurrence. If it is determined that the packet is causing congestion, the packet transmission to the switch unit is controlled according to a predetermined algorithm. As a result, the state of congestion occurring in the switch unit is controlled so as not to deteriorate and to be improved.

At this time, the buffers 104-1 to 104-n in each line unit 101 are configured so that the transmission of packets from each line unit 101 to the switch unit is not stopped.
Can be configured to receive packets up to a maximum storage capacity. This is a configuration for preventing the reception of a high-priority packet from becoming impossible, which makes it possible to transfer a high-priority packet without discarding it.

Further, according to the priority, the buffer 104-1
Among the packets distributed to ~ n, a packet with a low priority (which can be replaced with a packet with a low need) can be discarded, so that a packet with a high priority can be generated even in a congestion state. It becomes possible to prevent being discarded.

Based on the above, the configuration of the first embodiment of the present invention will be described in more detail with reference to FIG.

In the configuration shown in FIG. 1, each line unit 1
The line receiving unit 102 provided in 01 is connected to each line unit 101.
It terminates the line that is input from, and extracts the packet that is input in the form of an optical signal or an electrical signal. However, the configuration of the line receiving unit 102 can be variously modified and implemented without departing from the spirit of the present invention, and is not particularly limited in the present invention.

Further, the line receiving unit 102 which has extracted the packet in this way detects whether or not the received packet includes an error, and if it is detected that the error is included, this is the case. Is added to the packet and transmitted to the packet distribution unit 103 in the subsequent stage.

The packets thus extracted by the line receiving unit 102 are sorted by the packet sorting unit 103 according to the contents of the packets. For this content,
The details will be described below with reference to FIG. Further, the information necessary for distributing the packets in the packet distribution unit 103 can be set according to the condition (or situation) in which the packet switching device according to the present invention is used.

Next, the packets distributed according to the contents by the packet distribution unit 103 are temporarily stored in the buffers 104-1 to 104-n provided for each distribution destination.

Here, the packet distribution unit 103 is a buffer (buffers 104-1 to 104-1) to which packets are written.
(any one of n) is monitored to determine whether the packet can be written. Therefore, the buffer 104
The writing of the packet to 1 to n is performed by the buffer 104-
It is executed when the corresponding buffer in 1 to n is writable.

The storage capacity of each of the buffers 104-1 to 104-n is configured so that a plurality of maximum packets handled by the present invention can be accommodated sufficiently.
Further, this buffer is provided with the number of types (n of 1 to n) distributed by the packet distribution unit 103. However, as a method of configuring the buffers 104-1 to 104-n, it is assumed that a single buffer is divided and used for each address.

After that, the packets written in the buffers 104-1 to 104-n are those in the packet reading unit 105 for the packets which do not include a signal indicating an error.
It is read from 4-1 to n. This packet reading unit 10
The operation of reading by 5 is controlled by the congestion detection unit 106.

The congestion detection unit 106 also monitors the data amount of packets transmitted from the own line to the switch unit. Therefore, the congestion detection unit 106 reads a packet according to a predetermined algorithm based on the data amount of the packet transmitted to the switch unit within a certain fixed time (unit time).

As this operation, for example, the congestion detector 1
06 sets a plurality of thresholds with respect to the amount of data transmitted to the switch unit, and based on the amount of data transmitted per unit time with respect to this threshold, the buffer (104-1 Packet is read from any of the buffers (104-1 to 104-1).
The packet stored in (n) is discarded.

The packets read from the buffers 104-1 to 104-n by the packet reading unit 105 are transmitted to the switch unit (not shown) by the switching interface transmission unit 107.

Since the switch section and the switching interface transmission section 107 are implemented by being modified in various ways, they are not particularly limited here.

Further, in the switch unit, the congestion state in the switch unit is monitored from the data amount of packets stored in the buffer provided in the switch unit, and when this data amount exceeds a preset threshold value. In addition, the congestion notification signal is transmitted to each line unit 101 by a dedicated signal line.

With this congestion notification signal, the congestion detection unit 10
6 starts the operation of determining whether or not the own line is the cause of congestion that has occurred in the switch unit. As described above, this determination operation is performed based on the number of effective bits of the packet transmitted to the switch unit via the switching interface transmission unit 107 per unit time.

{Operation according to the first embodiment} The operation according to the first embodiment described above will be described in detail below with reference to the drawings.

The overall operation according to the first embodiment will be performed with reference to FIG. Referring to FIG. 1, in this figure, the signal input to the line is the line receiving unit 102.
Are extracted in the form of packets. Whether or not the extracted packet is normally transmitted on the normal transmission path is C
It is confirmed by RC (Cyclic Redundancy Check) or the like.

Here, error information (a signal indicating the above error) is added to the packet which is not correctly transmitted in the line receiving unit 102, and the packet is transmitted to the packet distributing unit 103.

The reason why the error information is added to the packet as described above is that the buffer (not shown) provided in the line receiving unit 102 cannot be written in addition to the error confirmation by the CRC described above. It is possible that the packet could not be received correctly for some reason.

Further, the packet allocating unit 103 corresponds the packet transmitted from the line receiving unit 102 to one of the preset buffers 104-1 to 104-n according to the priority stored in the header part of the packet. Send to things.

The priority stored in the header of this packet is, for example, RFC (Request For Comments) 79.
TOS (Type of Service) field in an IP (Internet Protocol) packet defined by 1
DS (DiffServ) code point defined by RFC2474 and RFC2475, and destination IP
It is determined according to the information in the packet such as the address.

This is generally settable according to the environment and situation in which the packet switching apparatus and the packet switching method are used. The RFC is an Internet research and development institute IETF (Internet Engineering Task Forc).
e) is a standard document regarding the use and services of TCI / IP, which is open to the public on the server on the Internet, and a number is added to each content.

In this embodiment, this RFC is quoted and R
FC791, 2474, and 2475 are applied. Further, FIG. 5 shows the format of an IP datagram as the above-mentioned packet configuration.

Referring to FIG. 5, the structure of the packet used in the present embodiment is such that the header section has the version number (version) of the IP header, the length of the IP header itself (header length), and the quality of service of IP (service type). ), The total length of the packet including the IP header and the IP data (packet length), an identifier for reconstructing the data whose upper position is divided, a flag for writing a control bit for dividing the packet, a fragment (division) Sequence number (fragment offset) for this packet, the time that this packet can exist on the network (time to live), the protocol of the upper position, the checksum for the IP header, the IP of the node that sent this packet Address (source IP address), destination IP address of this packet (destination I Address) is configured to have options for use during testing or debugging, padding, to adjust to an integral multiple sum of 32 bits of the option. Here, as the priority of the packet used in the present invention, the one stored in the above service type is used.

The packet distribution unit 103 also monitors whether or not the buffers 104-1 to 104-n to which the packet should be written can write the packet, and the line receiving unit 1
When a packet is received from 02, the buffer 104-
If the corresponding buffer in 1 to n can be written, the received packet is written.

When an error is included in the packet written at this time as described above, a signal indicating this error is added.

Further, the buffer 104, which is the write destination,
If the writing to any one of 1 to n is impossible, the packet distribution unit 103 interrupts the writing of the packet,
Reception of the packet from the line receiving unit 102 is suspended until the packet can be written in the buffer 104.

After that, in the buffers 104-1 to 104-n, if the signal indicating the error is added to the packet written by the packet distribution unit 103 as described above, the packet is sent to any of the buffers 104-1 to 104-n. The written packet is discarded without notifying the packet reading unit 105 that the is stored.

On the other hand, when the packet written in any of the buffers 104-1 to 104-n is a packet to which an error signal is not added, the buffer 10
Any one of 4-1 to n notifies the packet reading unit 105 that the packet is stored therein.

Further, the buffers 104-1 to 104-n perform the operation of discarding the stored packet in response to the notifications from the packet reading unit 105 and the congestion detection unit 106.

The packet reading unit 105 includes the congestion detection unit 10
The buffer 104, which is controlled by the control unit 6 and meets the predetermined condition, only in the state in which the reading from the buffer is possible.
The packets are read from 1 to n.

Further, the packet reading section 105, under the control of the congestion detecting section 106, selects an arbitrary buffer 104-1.
Causes ~ n to perform the operation of discarding the stored packet.

The congestion detection unit 106 constantly monitors the data amount of packets transmitted from the own line to the switching interface transmission unit 107, and based on the monitoring result and the congestion notification signal from the switch unit, the buffer 104- 1-n
Controls the reading of packets from any of the above.

Here, when the switch unit is not in the congestion state, that is, when the congestion notification signal is not input from the switch unit, the congestion detecting unit 106 causes the packet reading unit 105 to read.
Is permitted to read a packet from any of the buffers 104-1 to 104-n. Therefore, the packet reading unit 105 receives the packet read permission from the congestion detection unit 106, the buffers 104-1 to 104-1.
It operates to read a packet from the buffer corresponding to any one of n.

At this time, the operation of reading the packet from any of the corresponding buffers 104-1 to 104-n by the packet reading unit 105 follows a predetermined algorithm set in advance.

When the congestion notification signal notifies the congestion detection unit 106 that the switch unit is in the congestion state, the congestion detection unit 106 notifies the packet reading unit 105 of an algorithm different from the above. The packet reading unit 105 is controlled so as to read the packet from any of the buffers 104-1 to 104-n.

<Operation of Congestion Detection Unit 106> Corresponding buffer 104 when this switch unit is in a congestion state-
Regarding the control method of reading packets from 1 to n,
This will be described below.

In this operation, when the congestion notification signal is input from the switch unit to the congestion detection unit 106, first, the congestion detection unit 106 is switched to the switching interface unit 107.
It is determined whether or not the own line is the cause of congestion in the switch unit based on the data amount of the packet transmitted to the switch unit per unit time via the.

The criterion in this determination is determined based on a preset data amount threshold value and the number of effective bytes of the packet transmitted by the own line to the switch unit per unit time. However, in the present embodiment, the preset threshold value of the data amount is provided in a plurality of levels. This is, for example, a threshold (high level threshold),
When the threshold value is set in three stages of the threshold value (medium level threshold value) and the threshold value (low level threshold value), when the threshold value is exceeded, the highest priority packet is stored. The packet reading unit 105 is allowed to read packets from the buffers 104 (104-1 to 104-n), and when the threshold value is exceeded, the packet reading from all the buffers 104-1 to 104-n is performed. The packet stored in the buffer 104 (104-1 to n) configured to store the packet with the lowest priority is prohibited when the reading unit 105 exceeds the threshold value. It operates to execute control such as discarding according to a predetermined algorithm.

In order to prevent the congestion state in the switch section from being maintained for a long time, in this embodiment,
A timer is provided in the congestion detection unit 106 as shown in FIG.
By measuring the time during which the congestion notification signal continues to be input, if the measured time exceeds a preset time, the packet with the lowest priority among the packets stored in the buffers 104-1 to 104-n Configure to discard in order.

Here, referring to FIG. 2, the congestion detection unit 106
The operation of will be described in more detail.

The congestion detector 106, as shown in FIG.
The transmission packet amount monitoring unit 201, the read control circuit 202, and the timer 203 are included.

Here, the transmission packet amount monitoring unit 201
As described above, the own line monitors the number of effective bytes of the packet transmitted to the switch unit (hereinafter referred to as the transmitted packet amount) and the like, and notifies the read control circuit 202 of the monitoring result.

On the other hand, the read control circuit 202 sets the above-described preset value based on the transmission packet amount notified from the transmission packet amount monitoring unit 201 and the congestion notification signal from the switch unit. The packet reading unit 105 is controlled according to a predetermined algorithm.

{Effects of the First Embodiment} As described above, according to the first embodiment of the present invention, the switch unit which causes the packet switching device and the packet switching method to become large and expensive. It is possible to reduce the packet discard rate even when bursty traffic is received without increasing the storage capacity of the buffer provided in the.

Further, since the congestion state is detected for each line, it is possible to impose a packet restriction only on each line unit 101 which is the cause of actual congestion. This means that other lines can be operated normally.

Further, when congestion is detected in each line unit 101, the packet with the lower priority is discarded, so that the probability that the packet with the higher priority is discarded can be reduced. Therefore, it is possible to protect highly demanded information.

Further, since the congestion state is judged for each of a plurality of stages, it is possible to perform the control in the congestion state more than the control using the leased line.

[Second Embodiment] Next, a second embodiment of the present invention will be described in detail with reference to the drawings. The basic configuration of this embodiment is the same as that of the above-described first embodiment. On the other hand, in the second embodiment, the configuration is changed as follows.

That is, in the second embodiment, each line unit 10
By changing the configuration of the buffers 104-1 to 104-n for temporarily storing the packet received in No. 1, the protection of the high priority packet is realized at a higher level.

This is the buffer 104-1 in FIG.
In n to n, the buffer for storing the high priority packets has a relatively large storage capacity, while the buffer for storing the low priority packets has a relatively small storage capacity. It

With this configuration, in the second embodiment, when congestion occurs in the switch section, low priority packets are positively discarded before high priority packets. As a result, it becomes possible to protect a packet having a higher priority than in the first embodiment.

This is because when designing the system, it is necessary to sufficiently mount the buffers for all the priorities from the viewpoints of mounting problems and cost problems, and to discard high-priority packets. It is also effective when it is necessary to avoid it compared to the normal case.

[Third Embodiment] Further, in the basic configuration of the packet switching apparatus and the packet switching method shown in the above-described first embodiment, a dedicated line is used for notification of congestion from the switch unit to each line unit. However, in the third embodiment, this configuration is configured to use the switching interface receiving section in each line section.

FIG. 3 shows the configuration of a packet switching device and a packet switching method according to the third embodiment. Referring to FIG. 3, in the present embodiment, a congestion notification unit 322 for converting the congestion notification information output from the switch unit 321 into fixed-length data between each line unit 301 and the switch unit 321.
And a multiplexing unit 320 that multiplexes the congestion notification information converted into the fixed-length data as data to be input to the switching interface receiving unit 310.

In this configuration, the congestion notification information multiplexed with the packet and input to each line unit 301 is received by the switching interface reception unit 310, and then input to the separation unit 311.

Therefore, the separating unit 311 terminates the input data and separates this data into packets and fixed length data. Here, the separated packet is transmitted to the transmission buffer 309, and the fixed length data is the congestion detection unit 3
It is input to 06.

The fixed length data thus separated is judged by the congestion detection unit 306 whether or not it is the congestion notification information addressed to its own line, and if it is the congestion notification information addressed to its own line, the first According to a predetermined algorithm as shown in the embodiment of FIG.
The reading of packets from n is controlled.

This control method is the same as that in the first embodiment, and the packet with the highest priority is read according to the level of the congestion state generated in the switch section based on the threshold values provided in a plurality of stages. Is permitted and the packet with the lowest priority is discarded.

When a dedicated control line provided for congestion notification is used as in the first embodiment, only two types of judgment as to whether or not the switch section is in a congestion state can be made. However, as in the third embodiment,
Notify the congestion state of the switch part by fixed length data,
Further, the congestion detection unit 306 monitors the amount of packets transmitted to the switch unit of its own line, which enables more detailed notification of the congestion state as compared with the first embodiment.

However, in the third embodiment, the fixed length data input from the switching interface receiving unit 310 is terminated in each line unit 301, so that it affects other devices connected to the line. There is no such thing.

[0098]

As described above, according to the packet switching apparatus and the packet switching method of the present invention, the following effects can be obtained.

{Effects of the First Embodiment} First, according to the first embodiment of the present invention, a buffer provided in a switch unit that causes an increase in size and cost of a packet switching device and a packet switching method. Without increasing the storage capacity of
Even when bursty traffic is received, it is possible to keep the packet discard rate low.

Further, since the congestion state is detected for each line, it is possible to impose a packet restriction only on each line unit 101 which is the cause of actual congestion. This means that other lines can be operated normally.

Further, when congestion is detected in each line unit 101, the packet with the lower priority is discarded, so that the probability of discarding the packet with the higher priority can be reduced. Therefore, it is possible to protect highly demanded information.

Further, since the congestion state is judged for each of a plurality of stages, it is possible to perform the control in the congestion state as compared with the control using the leased line.

{Effects of the Second Embodiment} According to the second embodiment of the present invention, in addition to the effects of the first embodiment, protection of a packet having a high priority is realized at a higher level. It becomes possible.

{Effects of the third embodiment} Furthermore, according to the third embodiment of the present invention, the operation of the first embodiment is realized in accordance with the level of the congestion state that is occurring more. Is possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing a system configuration according to a first embodiment of the present invention.

FIG. 2 is a congestion detection unit 1 according to the first embodiment of the present invention.
It is a block diagram which shows the structure of 06.

FIG. 3 is a block diagram showing a system configuration in a third embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration example of a general high-speed router.

FIG. 5 is a block diagram showing a configuration example of a general IP datagram.

[Explanation of symbols]

101, 301 Each line section 102, 302 Line receiver 103, 303 Packet distribution unit 104-1 to n, 304-1 to n buffers 105, 305 Packet reading unit 106, 306 Congestion detection unit 107, 307 Switching interface transmitter 108, 308 Line transmitter 109, 309 Transmission buffer 110, 310 Switching interface receiver 201 Transmitted packet amount monitoring unit 202 Read control circuit 203 timer 311 Separation part 320 multiplex section 321 switch part 322 Congestion notification unit

Claims (8)

(57) [Claims] 1. A line receiving means for extracting a packet from data received from a line, a packet allocating means for allocating the packet received by the line receiving means for each assigned priority, and A plurality of buffering units provided with the number of assigned priority types and temporarily storing the packets sorted by the packet sorting unit for each priority, and reading the stored packets from the buffering unit. Packet reading means, congestion detecting means for measuring the number of effective bytes of the packet read by the packet reading means within a predetermined period, switching means for switching the packet read by the packet reading means, and the switching means If congestion has occurred in, the congestion notification signal is output. And a congestion notifying unit that has the lowest value as the predetermined threshold value.
A first threshold and a second threshold having a value larger than the first threshold
Value and a third threshold value having a value larger than the second threshold value,
It has been set in advance, and the congestion is notified by the congestion notifying means.
When the notification signal is notified, the congestion detection means
The effective number of bytes measured by
As a result of the comparison, the number of valid bytes is the first
If it exceeds the threshold of
The highest priority packet is stored
Only read the packet from the buffering means
It is controlled so as to permit, and the result of the comparison is the second threshold value.
If it exceeds the value,
The packets from all the buffering means
Is controlled so that the reading of
If the third threshold is exceeded, the packet read
Means that the lowest priority packets are stored
The package stored in the buffering means
A packet switching device characterized in that the packet is controlled so as to be discarded . Wherein said congestion notification signal, packet switching apparatus according to claim 1, wherein the input to the congestion detecting means via a dedicated control line. 3. A multiplexing means for multiplexing the packet and the congestion notification signal, and a separation means for separating the packet and the congestion notification signal multiplexed by the multiplexing means. The packet switching device according to claim 1 or 2 , wherein the congestion notification signal is input to the congestion detecting means via a transmission line common to the packets. Wherein said plurality of buffering means, the priority is higher the buffering means for storing the high packet, the packet switching apparatus according to claim 1, wherein the increasing constituting the storage capacity. 5. A line receiving step of extracting a packet from data received from a line, a packet sorting step of sorting the packet received in the line receiving step for each assigned priority, and a packet assigning step A buffering step of temporarily storing the packets sorted by the packet sorting step for each of the priorities in a buffer provided with the number of types of the given priority, and reading the stored packets in the buffering step. A packet reading step, a congestion detection step of measuring the number of effective bytes of the packet read within a predetermined period in the packet reading step, and a switching step of switching the packet read in the packet reading step , If congestion occurs in the switching process, congestion And a congestion notification step of outputting a known signal, wherein the congestion detection step, the congestion notification step by the congestion
When the notification signal is notified, the valid bar
And the maximum value preset as the predetermined threshold.
A low first threshold value, a second threshold value greater than the first threshold value
A threshold value and a third threshold value having a value larger than the second threshold value,
As a result of the comparison, the number of valid bytes is the first
If it exceeds the threshold of
And the packet with the highest priority is stored.
Only allow reading of the packet from the buffer
Control so that the result of the comparison exceeds the second threshold value.
If there is, in the packet reading process, before all
It is prohibited to read the packet from the buffer.
As a result of the comparison, the third threshold value is exceeded.
If there is, the highest priority in the packet reading process
Stored in the buffer where low-frequency packets are stored
A packet switching method, characterized in that control is performed so that the stored packet is discarded . 6. The packet switching method according to claim 5 , wherein the congestion notification signal is transmitted via a dedicated control line. 7. The method further comprises a multiplexing step of multiplexing the packet and the congestion notification signal, and a separation step of separating the packet and the congestion notification signal multiplexed in the multiplexing step. 7. The packet switching method according to claim 5 , wherein the congestion notification signal is transmitted via a transmission line common to the packets. Wherein said buffer is as the buffer in which the priority is to store high packet, packet switching method of claim 5, wherein the increasing constituting the storage capacity.