JP2003298601A - Packet sorting apparatus, overflow processing method, program and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable normal sorting processing and transmitting packets in a normal sequence even if overflow processing is performed to packets stored over a buffering capacity. <P>SOLUTION: A packet sorting apparatus receives packets in which sequence numbers are added to a header information part to store temporarily into a sorting buffer 112 and extracts packets from the buffer 112 in order of the sequence numbers. A packet retention number counting part 102 counts the number of packets stored into the buffer 112, when the counted number exceed a predetermined number, a sorting control part 107 discards a packet to be extracted at first among the packets stored into the buffer 112. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet rearrangement device, an overflow processing method, a program, and a storage medium, and more particularly to receiving a packet having a sequence number added to a header information section and temporarily storing it in a buffer. Then
A packet rearrangement device that extracts packets from the buffer in order of sequence numbers and outputs the packets, an overflow processing method applied to the packet rearrangement device, and a program for causing a computer to execute the overflow processing method.
And a storage medium storing the program.

[0002]

2. Description of the Related Art Conventionally, a parallel multiplex transmission line and a plurality of communication devices (nodes) have been used as a communication system for transmitting and receiving packets.
There is a communication system composed of and. The parallel multiplex transmission path is composed of a plurality of communication paths, and packets are transmitted while being distributed so that the packets flow evenly in each communication path. Therefore, in this communication system, the order of the packets arriving at the receiving node is not guaranteed.

That is, at the time of transmission from the transmission side node to the reception side node, packets are randomly transmitted to a plurality of transmission paths, and packets are transmitted from the relay node depending on the congestion in the buffer of the relay node. Due to the delay, the arrival order of the packets to the receiving side node is random, and the order of the packets arriving at the receiving side node is not guaranteed.

FIG. 7 is a block diagram showing an example of the configuration of a communication system including a parallel multiplex transmission line and a plurality of communication devices (nodes).

In the figure, 301 to 304 are node devices, and 30
5 to 308 are exchange switches, 309 to 312 are buffers, 341 to 344 are terminal interface units, and 321 to
336 is a terminal, and A, B, C and D are parallel transmission lines forming a ring.

Next, the communication operation performed in this communication system will be briefly described with reference to FIG.

The network of this communication system has a plurality of ring-shaped parallel transmission lines A, B, C and D, and the parallel transmission lines are mutually connected by exchange switches 305 to 309. Each of the terminals 321 to 336 has a parallel transmission path A,
When communicating with a terminal connected to one parallel transmission line of B, C, and D and connected to another parallel transmission line, the packet is transmitted at least once to the other parallel transmission by the exchange switch. Communication is performed by switching to the road. In this case, the position at which packet switching is performed is not specified, but the node device immediately before the destination node device is switched to the parallel transmission path of the destination, and each node device does not particularly guarantee the packet transmission order, The communication control becomes easy by distributing the data in arbitrary parallel transmission paths.

In this communication system, in order to simplify the configuration of the node device, the exchange switches 305 to 308 change the input / output connection relationship at a constant cycle according to a specific cyclic pattern regardless of the input packet, and the buffer 309.
312, the input packets are temporarily stored, and when the input / output connection relations of the exchange switches 305 to 308 have a desired relation, the packets are read out from the buffers 309 to 312 to perform exchange.

For example, when a packet is transmitted from the terminal 322 to the terminal 332, the packet output from the terminal 322 is the terminal interface unit 341 of the node device 301.
Then, the sequence number is inserted into the packet header and then temporarily stored in the buffer 309. Then, when the input terminal IN2 of the exchange switch 305 is connected to the output terminal OUT2, for example, a packet is read from the buffer 309, output to the transmission line B, and temporarily stored in the buffer 310 of the node device 302. . Then, when the input terminal IN2 and the output terminal OUT4 of the exchange switch 306 are connected. The packet is read from the buffer 310,
It is output to the transmission path D.

At this time, the transmission order of the packets may be changed, but the packets separated from the transmission path D are rearranged in sequence number order in the terminal interface section 343 and then sent to the terminal 332.

In this way, communication is performed by transferring packets to different parallel transmission paths in the node device.

FIG. 8 shows the terminal interface units 341 to 341.
FIG. 44 is a block diagram showing an internal configuration of 44. Since the terminal interface units 341 to 344 have the same configuration, one of them is referred to as the terminal interface unit 400. The configuration of the terminal interface unit 400 shown here is the configuration of a conventional terminal interface unit.

The terminal interface section 400 comprises a header conversion section 401 and a rearrangement section 402. The header conversion unit 401, when transmitting a packet to the network,
A sequence number is added to the packet header corresponding to the packet transmission order. The rearrangement unit 402 rearranges the randomly arrived packets in sequence number order.

FIG. 9 is a block diagram showing the internal structure of the rearrangement unit 402 for one connection.

In the figure, reference numeral 500 denotes a sequence number separating section for separating a sequence number from the header information of the packet, and 50.
Reference numeral 1 is a read pointer ring counter for generating an address for reading packets from the rearrangement buffer 502, and 502 is a rearrangement buffer for temporarily storing packets and transmitting the packets in sequence number order. The unit 503 controls this. The rearrangement buffer 502 includes 512 storage areas assigned storage addresses 0 to 511, for example, and each storage area includes two storage areas for storing packet data and a store flag. The store flag is a flag that indicates that the packet data is written in the corresponding storage area by "1" and that the packet data is not written by "0".

Next, the operation of the rearrangement section 402 will be described.

The packets separated and output toward the terminal are sent to the terminal interface section (400, FIG. 8) through the sub transmission path. The terminal interface unit is controlled by the rearrangement control unit 503, and when writing a packet, the sequence number separation unit 500
A write pointer is generated according to the sequence number on the packet header, the packet data is written in the storage area of the rearrangement buffer 502 pointed to by the pointer, and the store flag “1” is written.

In reading a packet, the read pointer ring counter 501, which is incremented each time a packet is read, generates a read pointer and refers to the store flag stored in the storage area of the rearrangement buffer 502 indicated by the pointer. If the store flag is “1”, it means that the packet data is written in the corresponding storage area of the rearrangement buffer 502, so that the packet data is read and the packet is transmitted to the terminal. "0"
Set to. Then, the read pointer ring counter 501 is incremented to generate a pointer value corresponding to the sequence number to be read next.

If the referred store flag is "0", it means that the packet has not arrived yet. Therefore, until the packet to be read arrives and the store flag becomes "1", the packet data Wait for reading.

By doing so, randomly arrived packet data can be rearranged in sequence number order and transmitted to the terminal.

The rearrangement buffer 502 shown in FIG.
In the example of the communication system using, the sequence numbers are added to the packets in order from 0 to 511, and after the addition of 511, the sequence number is returned to 0 and the addition is performed. Therefore, a packet with the same sequence number appears for each packet of the maximum value (512 packets). This maximum value is set to a value that is sufficiently larger than the maximum amount of exchange that can occur when the order of packets is exchanged during their propagation through the network.

[0022]

By the way, in general, a communication processing apparatus needs a function of temporarily buffering communication data (packets), and its functional section is responsible for quality assurance such as rate control. In addition to the above, when a signal for prohibiting the transmission of data is sent from the communication processing device in the subsequent stage, overflow processing may be performed on the packet accumulated exceeding the buffering capacity. In overflow processing, generally, a packet that arrives after the buffering capacity is exceeded is simply discarded.

However, the above-mentioned conventional rearrangement unit 4
In 02, when an overflow occurs, if a newly arrived packet is simply discarded, a sequence number sequence corresponding to a packet to be read out is omitted. Therefore, there is a problem that the rearrangement process cannot be performed normally.

More specifically, when the sequence number string is omitted due to the discard of the packet, the rearrangement buffer 502
In this case, the store flag does not become "1" in the storage area corresponding to the missing sequence number. Therefore, at the time of packet reading, the rearrangement unit 402 stops operating in a packet data read standby state.

Further, when packets are continuously transmitted from the transmitting side while the packet reading is stopped as described above, a packet having the same sequence number as the packet staying in the rearrangement buffer 502 eventually arrives. It will be. As a result, there is a problem that the previous packet data is destroyed (overwritten or discarded) by a new packet having the same sequence number, and the packet cannot be transmitted in a normal sequence.

The present invention has been made in view of the above problems, and even if overflow processing is performed on a packet stored in excess of the buffering capacity,
A packet rearrangement device capable of performing normal rearrangement processing and transmitting packets in a normal sequence,
An object is to provide an overflow processing method, a program, and a storage medium.

[0027]

In order to achieve the above object, according to the invention of claim 1, a packet having a sequence number added to a header information section is received and temporarily stored in a buffer, In a packet rearrangement device that extracts packets from the buffer in order of sequence numbers and outputs the packets, a measuring unit that measures the number of packets stored in the buffer, and a number measured by the measuring unit exceeds a predetermined number. A packet rearranging device is provided, which comprises: a discarding unit that discards a packet to be extracted first among the packets stored in the buffer.

According to the invention described in claim 10, the packet having the sequence number added to the header information portion is received and temporarily stored in the buffer, and the packet is taken out from the buffer in the sequence number order and outputted. In an overflow processing method applied to a packet rearrangement device, a measuring step of measuring the number of packets stored in the buffer, and storing in the buffer when the number measured by the measuring step exceeds a predetermined number. A discarding step of discarding the first packet to be extracted among the stored packets.

Further provided is a program for causing a computer to execute the overflow processing method, and a computer-readable storage medium storing the overflow processing method as a program.

[0030]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a block diagram showing the arrangement of a first embodiment of a rearrangement section according to the present invention. This rearrangement unit is provided in the terminal interface unit of the node device. The configuration other than the above-mentioned rearrangement unit is the same as the configuration shown in FIGS. 7 and 8.

The sorting section in the first embodiment is
Overflow determination unit 100 and rearrangement control unit 107
And a rearrangement buffer 112. The sorting control unit 107 and the sorting buffer 112 are shown in FIG.
Each of them has the same configuration as the sorting control unit 503 and the sorting buffer 502 shown in FIG. 3, and when a packet is input, the sequence number separating unit 108 separates the header portion of the input packet and uses the sequence number in the header Generate a write pointer for the packet. The packet data is held in the storage area of the sorting buffer 112 pointed to by the write pointer, and the store flag of the storage area in the sorting buffer 112 is set to "1".

When reading a packet, the read pointer ring counter 109 generates a read pointer and refers to the store flag held in the storage area of the rearrangement buffer 112 pointed to by the read pointer. as a result. If the store flag is set to "1", it means that the packet data is held in the same storage area. Therefore, the packet data held in the same storage area is read and the packet is output to the terminal. At the same time, the store flag is set to "0" and the read pointer ring counter 109 is incremented by 1 to search the storage area of the next packet. Since the read pointer ring counter 109 is a ring counter that monotonically increases by 1, the packet reading order is rearranged in sequence number order and read.

The overflow determination unit 100 includes a packet retention number threshold value holding unit 101 and a packet retention number measurement unit 10.
2 and a comparison unit 103. The packet retention number threshold holding unit 101 is set in advance to, for example, “100”.
Holds the threshold. Packet retention number measuring unit 102
Counts up using the packet write signal 105 generated when the sorting control unit 503 writes the packet data in the sorting buffer 502. In addition, the packet retention number measuring unit 102 includes a rearrangement control unit 5
03 receives the packet read signal 104 generated when reading the packet data from the rearrangement buffer 502, and counts down.

2 to 4 are diagrams showing an example of a state of holding packet data in the rearrangement buffer 112. As shown in FIG.

In FIG. 2, the read stop instruction is input, and the packet read is stopped while the read pointer points to the storage area of the number 156 in the rearrangement buffer 112, while the packet write is continued. There is. When the inflow of packets continues, the packet retention number measuring unit 102 only increments. In FIG. 2, packets are not held in the storage areas 162 and 160, but this indicates that the packets have not arrived because they are transmitted randomly.

The comparing unit 103 is a packet retention number measuring unit 1
02 count value and packet retention number threshold value holding unit 101
When the count number exceeds the threshold value, the overflow occurrence signal is output to the rearrangement control unit 107.

FIG. 3 shows a state in which packets are accumulated in the storage areas of the numbers 156 to 256 in the rearrangement buffer 112. Here, when a packet is newly written in the storage area of number 259, the overflow occurrence signal is output to the rearrangement control unit 107. Also in FIG. 3, the number 25
Although no packet is held in the storage area of 8,257, this also indicates that the packet has not arrived.

As described above, the rearrangement control unit 107 which receives the overflow occurrence signal performs the overflow process.

FIG. 5 is a flowchart showing the procedure of overflow processing performed by the rearrangement control unit 107.

A normal rearrangement process is performed in step S1, and it is determined in step S2 whether or not an overflow occurrence signal is received from the overflow determination unit 100.
If the overflow occurrence signal is received, step S3
If not received, the process returns to step S1.

In step S3, the storage area in the rearrangement buffer 112 pointed to by the read pointer (see FIG. 3).
In this example, the store flag in the storage area of number 156) is read and it is confirmed that it is valid. If it is valid, the process proceeds to step S3, and if it is invalid, the process proceeds to step S8.

In step S4, the packet data held in the storage area in the rearrangement buffer 112 pointed to by the read pointer is discarded and the store flag of the storage area is set to "0". FIG. 4 shows discarding of packet data in the storage area of number 156.

In step S5, the count number of the packet retention number measuring unit 102 is decremented by 1.

In step S6, the read pointer ring counter 109 is incremented by one. Figure 4
Shows the state where the read pointer ring counter 109 is incremented and the read pointer becomes “157”.

In step S7, the packet read by the read pointer is read out, and the process returns to step S1.

In step S8, since the store flag is invalid, it is determined that a defect has occurred, and error processing is performed in step S9.

As described above, by discarding the packet to be read first among the packets staying in the rearrangement buffer 112, the sequence number sequence corresponding to the packet to be read from now is not lost, and the rearrangement is performed. The processing can be performed normally. That is, the problem that the packet having the same sequence number as the packet staying in the rearrangement buffer 112 arrives and the packet data is destroyed (overwritten or discarded) and the transmission error rate increases is solved. be able to.

(Second Embodiment) FIG. 6 is a block diagram showing the configuration of a second embodiment of a rearrangement section according to the present invention. This rearrangement unit is provided in the terminal interface unit of the node device. The configuration other than the above-mentioned rearrangement unit is the same as the configuration shown in FIGS. 7 and 8.

In the first embodiment, it is assumed that the overflow judgment unit 100 corresponds to one connection, but in the second embodiment, the overflow judgment unit 200 has a plurality of (N) connections. Corresponding to. Therefore, the overflow determination unit 200 includes the packet retention number counter table memory 210. The packet retention number counter table memory 210 is composed of RAM, has a storage area for N connections, and holds the packet retention number therein.

In the second embodiment, the packet retention count measuring unit 202 uses the packet retention count counter table memory 210 corresponding to the connection when writing a packet.
Of the packet retention number counter table memory 210 corresponding to the connection at the time of packet reading, and retains in this area. The accumulated packet retention number is decremented, and thereby the packet retention number is measured for each connection. Further, at the time of writing a packet, the comparison unit 203 reads the packet retention number from the storage area of the packet retention number counter table memory 210 corresponding to the connection, and also reads the threshold value corresponding to the connection from the packet retention number threshold value holding unit 201. To compare. If the packet retention number exceeds the threshold value, an overflow occurrence signal is output.

In the rearrangement control section (not shown), overflow processing is performed for each connection. The overflow process itself is the same as in the first embodiment.

As described above, even in the case of a plurality of connections, a packet having the same sequence number as the packet staying in the rearrangement buffer arrives, or packet data is destroyed (overwritten or discarded) and a transmission error occurs. The problem that the rate increases can be solved.

(Other Embodiments) The program code itself of the software that realizes the functions of the above-described embodiments may constitute the present invention, and the storage medium storing the program code is the main program. You may comprise invention.

In this case, the program code itself read from the storage medium realizes the function of each of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. .

As a storage medium for supplying the program code, for example, a floppy (registered trademark) disk,
Hard disk, optical disk, magneto-optical disk, CD-
ROM, CD-R, magnetic tape, non-volatile memory card, ROM, etc. can be used.

Further, by executing the program code read by the computer, not only the functions of the respective embodiments described above are realized, but also the OS and the like running on the computer based on the instructions of the program code. Does some or all of the actual processing, and the functions of the above-described embodiments are realized by the processing,
Needless to say, it is included in the present invention.

Further, after the program code read from the storage medium is written in the memory provided in the function expansion board inserted into the computer or the function expansion unit connected to the computer, based on the instruction of the program code, It is needless to say that the present invention also includes a case where the CPU or the like included in the function expansion board or the function expansion unit performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments. Yes.

[0059]

As described above in detail, according to the present invention, when a packet is going to be stored exceeding the buffering capacity of the buffer, the packet having the sequence number order to be taken out first is discarded from the buffer. Thus, the sequence number sequence of the packet to be read will not be lost, the rearrangement process can be performed normally, and the packet can be transmitted in the normal sequence. Therefore, the problem that the packet having the same sequence number as the packet staying in the buffer arrives and the problem that the packet data is destroyed (overwritten or discarded) and the packet is not transmitted in a normal sequence are solved. It

[Brief description of drawings]

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

FIG. 2 is a diagram showing an example of a holding state of packet data in a rearrangement buffer.

FIG. 3 is a diagram showing an example of a holding state of packet data in a rearrangement buffer.

FIG. 4 is a diagram showing an example of a holding state of packet data in a rearrangement buffer.

FIG. 5 is a flowchart showing a procedure of overflow processing performed by a rearrangement control unit.

FIG. 6 is a block diagram showing a configuration of a second exemplary embodiment of a rearrangement unit according to the present invention.

FIG. 7 is a block diagram showing an example of a configuration of a communication system including a parallel multiplex transmission line and a plurality of communication devices (nodes).

FIG. 8 is a block diagram showing an internal configuration of a terminal interface unit.

FIG. 9 is a block diagram showing an internal configuration of a rearrangement unit for one connection.

[Explanation of symbols]

100 overflow determination unit 101 packet retention number threshold retention unit 102 packet retention number measurement unit (measurement means, counter) 103 comparison unit 104 packet read signal 105 packet write signal 106 overflow occurrence signal 107 rearrangement control unit (discard means, packet write) Means, packet reading means, judging means) 108 sequence number separating section 109 read pointer ring counter (ring counter) 110 store flag information 111 packet input information 112 rearrangement buffer (buffer) 200 overflow judging section 201 packet retention number threshold holding section 202 packet retention number measurement unit 203 comparison unit 210 packet retention number counter table memory (storage unit) 301 to 304 node device (communication device) 305 to 308 exchange switch 30 ～312 buffer 321-336 terminals 341 to 344 terminal interface unit 400 terminal interface unit 401 header converting section 402 sorting unit

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5K030 GA13 HA08 KA03 LC11 MA13                       MB13 MB15                 5K031 AA07 DA11 DB11                 5K033 AA05 CB06 DB13 EA03                 5K034 AA06 EE11 HH01 HH02 HH63                       MM11

Claims (12)

[Claims] 1. A packet reordering device for receiving a packet having a sequence number added to a header information part, temporarily storing the packet in a buffer, extracting the packet from the buffer in sequence number order, and outputting the packet. Measuring means for measuring the number of stored packets, and discarding means for discarding the first packet to be taken out of the packets stored in the buffer when the number measured by the measuring means exceeds a predetermined number. A packet reordering device comprising: 2. The measuring means comprises a counter that increments each time packet data is written to the buffer and decrements each time packet data is read from the buffer. Packet sorter. 3. The packet rearrangement apparatus according to claim 2, wherein the counter decrements when the discarding means discards the packet data. 4. A packet writing unit for writing data of the received packet in a storage area of the buffer having the same number of addresses as the sequence number added to the received packet, and a storage area number of the buffer. A ring counter having the same maximum count value and counting up each time packet data is read from the buffer, and a packet reading packet data from the storage area of the buffer having the same number of addresses as the count value of the ring counter. The discarding means further includes a reading means, and when the number measured by the measuring means exceeds a predetermined number, the discarding means writes in the storage area of the buffer having the same number of addresses as the count value of the ring counter. The packet data that has been discarded is discarded. The packet rearrangement device according to any one of the above. 5. The packet reordering device according to claim 4, wherein the ring counter counts up when the discarding means discards the packet data. 6. Each storage area of the buffer has a first area for storing packet data and a second area for storing a flag for indicating that the packet data is stored in the first area. When the number measured by the measuring means exceeds a predetermined number, the discarding means has a second storage area of the buffer having the same number of addresses as the count value of the ring counter.
6. The packet rearrangement apparatus according to claim 4 or 5, wherein if a valid flag is present in the area, the packet data stored in the first area of the storage area is discarded. 7. A valid flag exists in the second area of the storage area of the buffer having the same number of addresses as the count value of the ring counter when the number measured by the measuring means exceeds a predetermined number. The packet rearrangement apparatus according to claim 6, further comprising a determination unit that determines that an abnormality has occurred, if not. 8. The packet rearrangement device is provided in each of the plurality of communication devices in a communication system including a plurality of parallel transmission lines and a plurality of communication devices provided in the middle of the plurality of parallel transmission lines. Further comprising a storage unit for storing the number of packets measured by the measurement unit for each of the plurality of parallel transmission paths, wherein the discarding unit is a processing target among the number of packets stored by the storage unit. The packet rearrangement apparatus according to any one of claims 1 to 7, wherein the number of packets corresponding to the parallel transmission path is read and the discarding is executed. 9. The plurality of communication devices in a communication system, wherein the packet rearrangement device is composed of a plurality of ring-shaped parallel transmission lines and a plurality of communication devices provided in the middle of the plurality of parallel transmission lines. 9. The packet rearrangement apparatus according to claim 1, wherein each packet is transmitted to the packet rearrangement apparatus in an order irrelevant to the sequence number order. 10. A packet in which a sequence number is added to a header information part is received and temporarily stored in a buffer,
In an overflow processing method applied to a packet rearrangement device that extracts packets from the buffer in order of sequence number and outputs the packets, a measuring step of measuring the number of packets stored in the buffer, and a number measured by the measuring step. When the number of packets exceeds a predetermined number, the discarding step of discarding the packet to be taken out first out of the packets stored in the buffer. 11. A packet in which a sequence number is added to a header information part is received and temporarily stored in a buffer,
In a program for causing a computer to execute an overflow processing method applied to a packet reordering apparatus that extracts packets from the buffer in order of sequence numbers and outputs the packets, the overflow processing method is the number of packets stored in the buffer. And a discarding step of discarding the first packet to be taken out of the packets stored in the buffer when the number measured by the measuring step exceeds a predetermined number. Program to do. 12. A packet in which a sequence number is added to a header information part is received and temporarily stored in a buffer,
In a computer-readable storage medium that stores as a program an overflow processing method applied to a packet rearrangement apparatus that extracts packets from the buffer in order of sequence numbers and outputs the packets, the overflow processing method is stored in the buffer. And a discarding step of discarding the first packet to be retrieved among the packets stored in the buffer when the number measured by the measuring step exceeds a predetermined number. A storage medium characterized by the above.