JP2006245732A - Packet buffer device, packet relay transfer device, and network system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maximally maintain the transmission quality of a voice packet even in a state of a buffer overflow without deteriorating the quality of either of the voice packet and a video packet alone, when transmitting the voice packet and the video packet. <P>SOLUTION: The packet buffer device is provided with a means 101 for attaching a flag to discriminate a packet type which adds a flag corresponding to the type of an inputted packet to a packet; a FIFO packet storage means 102 which stores the packet with the flag attached by the means 101, and outputs the packet to a FIFO output port; a means 103 for monitoring a storage amount of buffers which monitors a storage amount of the packets stored in the FIFO packet storage means 102; and a packet discarding means 104 for preferentially discarding the specific type of the packet from the FIFO packet storage means 102 by receiving an outputted packet discarding signal, when the means 103 for monitoring the storage amount of the buffers detects that there is no available space in the FIFO packet storage means 102. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a packet buffer device, a packet relay transfer device, and a network system used when packetizing and distributing audio data and video data together with control information on a packet communication network such as an IP network.

  In communication on a packet communication network, a data string to be transmitted is transmitted and received together with additional information called a finely divided header. For example, in communication on an IP network, all data is transmitted / received in units of processing of data pieces called IP packets.

  In general, in communication over a packet communication network, packets are temporarily stored in order to smooth the amount of transmission data that changes every moment and use the communication path as efficiently as possible, and to prevent data loss between communication paths with different communication speeds. An accumulating buffer device is used.

  On the other hand, in recent years, devices such as IP telephones that transmit and receive voice in IP packets on an IP network have been used. However, when voice data has a lot of delay and omission, it is the basic purpose of telephone conversation. Therefore, a method is used in which a voice packet is transmitted with a specially high priority in distinction from other packets.

  Conventionally, in a packet buffer device used for such a purpose, a method of using a plurality of queues separated for each packet processing priority and storing a packet for each priority for each queue has been used.

  Methods for outputting packets stored in the plurality of priority queues can be roughly classified into two types. The first method is a method for reading and transmitting a packet from the queue as long as the packet is stored in the high priority queue (see, for example, Patent Document 1).

The second method is a method of providing a packet transmission scheduler means and determining which queue packet is to be output based on the number of packets in the queue, the packet input / output rate, and the like (see, for example, Patent Document 2). .
Japanese Patent Laid-Open No. 11-41288 JP 2002-185503 A

  The first method can be realized with a simple mechanism, but when the high priority queue stays, the high priority packet is output continuously, so the low priority packet is not output, and the high priority queue becomes empty. There was a problem that the low-priority packets were continuously output from the low-priority queue later.

  For example, in a system that transmits and receives both audio and video data in IP packets, such as an IP videophone, in the unlikely event that buffer overflow is unavoidable due to an abnormality in the transmission system, it is possible to give priority to voice packets. There is a case where a specification for discarding a video packet first is required without being discarded as much as possible.

  This is because the permissible range of data loss is relatively larger in video than in audio in human sense. However, when the first method is used, audio packets are preferentially transferred even when there is no buffer overflow, so that a delay occurs in the video packets, the video quality deteriorates, and the video and audio are synchronized. There was a problem that it was difficult to take.

  The second method can solve this problem, but has a problem that the circuit for scheduling becomes complicated and the circuit scale becomes large.

  It is an object of the present invention to transmit audio packets and video packets at the same time without degrading the quality of either the audio or video, and even when the buffer overflow is unavoidable. An object of the present invention is to realize communication with simple hardware that can maintain packet transmission and maintain communication quality.

  The packet buffer device according to the present invention includes a packet type determination flag adding unit that adds a flag according to the type of a packet input from an input port to the packet, and stores the packet flagged by the packet type determination flag adding unit to store the packet in advance. First-in first-out type packet storage means for outputting to the output port in advance, buffer accumulation amount monitoring means for monitoring the accumulated amount of packets accumulated in the packet storage means, and the buffer accumulation amount monitoring means are the packet storage A packet discard unit for receiving a packet discard signal output when it is detected that the unit is empty, and discarding a specific type of packet preferentially from the packet storage unit.

  In the present invention, the packet storage means comprises descriptor sequence holding means for storing a plurality of descriptors describing packet control information in order and a memory for storing packets, and packet control information described by the descriptors Is a memory address specifying the packet storage area, an empty flag indicating whether or not the packet storage area specified by the address is in an empty state in which no packet is stored, and the packet specified by the address And a high priority flag for displaying whether or not the packet stored in the storage area is of high priority.

  In the present invention, the packet storage means reads the packet stored in the storage area at the memory address designated by the first descriptor of the ordered descriptor string, and changes the empty flag of the descriptor to an empty display, The order of the descriptor is lowered to the end of the ordered descriptor string, and the rank of descriptors other than the descriptor in the ordered descriptor string is raised one by one.

  In the present invention, the packet storage means writes the packet to the storage area of the memory address designated by the descriptor having the highest rank among the descriptors in which the empty flag indicates an empty state in the ordered descriptor string, Change the descriptor's empty flag to a non-empty display, set the descriptor's high priority flag according to the priority of the input packet, lower the descriptor's rank to the end of the ordered descriptor string, When the order of descriptors lower than the order of the descriptor in the ordered descriptor column is increased by one, and there is no descriptor whose empty flag indicates an empty state in the ordered descriptor column, Ordered descriptor Write a packet to the storage area at the memory address specified by the descriptor specified by the predetermined rule among the descriptors indicating that the high priority flag is not high priority in, and set the empty flag of the descriptor to not empty Change to display, set the high priority flag of the descriptor according to the priority of the input packet, lower the rank of the descriptor to the end of the ordered descriptor string, and the descriptor in the ordered descriptor string The rank of the descriptors lower than the rank of 1 is increased by one.

  In the present invention, the predetermined rule specifies a descriptor having the lowest rank among the descriptors indicating that the high priority flag is not high priority in the ordered descriptor column.

  According to the packet buffer device having the above-described configuration, the function of adding a flag according to the type to a plurality of types of packets having different priorities, and the buffer when a packet is accumulated until a new packet cannot be input to the buffer. For example, when a voice packet and a video packet are transmitted at the same time, normally the voice packet and the video packet are handled with the same priority, and the transmission system When the buffer overflow becomes unavoidable due to the abnormality of the video packet, the video packet can be discarded first, and the transmission quality of the voice packet can be maintained as much as possible.

  Further, the first-in first-out type packet storage means is composed of a descriptor string holding means for storing descriptors in order and a memory for storing packets, so that a specific type in consideration of a packet first-in first-out control function and packet priority The packet discard function can be realized with simple hardware.

  The packet relay and transfer apparatus of the present invention includes a packet buffer apparatus of the present invention, one or more first-in first-out type packet storage means, and packet priority determination means for determining the priority of an input packet in three or more stages. A packet output selection means for selecting and outputting a packet stored in the packet buffer device or the first-in first-out packet storage means, wherein the packet priority determination means is a highest priority or a second priority. Is input to the packet buffer device, the packet determined to be lower than the third priority is input to the first-in first-out packet storage means, and the packet output selection means is connected to the packet buffer device. When a packet is stored, the packet stored in the packet buffer device is selected and output, and the packet buffer When packet location is not stored selects and outputs the packet stored in the FIFO type packet memory means.

  The network system of the present invention includes an audio input means, a video input means, a packetizing means for packetizing input audio data and video data, adding packet priority information to each packet, and outputting the packet data. A transfer device.

  In the present invention, the packetizing means packetizes the audio data by adding information that the packet relay transfer device determines as the highest priority, and information that determines the video data as the second priority. Is added to form a packet.

  According to the packet relay / transfer apparatus or network system configured as described above, in addition to video packets and audio packets, real-time transmissions such as device control information packets, web browsing packets, and e-mail packets with relatively low real-time transmission requirements. Priority is given by making the priority of the audio packet the highest priority, the priority of the video packet as the second priority, and the priority of the other packets as the third priority when packets with few requests are mixed. Since a packet can be selected and relayed based on the degree, it is possible to perform an optimal relay transfer for each packet.

  In the present invention, there is provided priority switching instructing means for instructing switching of priority information to be added to a packet, and the packetizing means adds information for identifying the voice data as the highest priority by the packet relay transfer apparatus. Packetizing the video data by adding information that the packet relay transfer device determines as the second priority, and adding the information that the packet relay transfer device determines as the second priority. The operation of packetizing the video data and adding the information that the packet relay transfer device determines as the highest priority to packetize the video data is switched according to the instruction of the priority switching instruction means.

  According to the above configuration, the priority of the audio packet and the priority of the video packet can be switched as necessary or based on a predetermined rule, so that the relay transfer can be flexibly controlled according to the network situation. Is possible.

  According to the present invention, when an audio packet and a video packet are transmitted simultaneously, usually the audio packet and the video packet are handled with the same priority, so that the quality of one of the audio or the video is deteriorated or the video and the audio are synchronized. In the unlikely event that buffer overflow is unavoidable due to a transmission system failure, video packets are discarded first, and transmission of audio packets is maintained as much as possible to maintain communication quality. Can be maintained.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a basic configuration of a packet buffer device according to Embodiment 1 of the present invention. In FIG. 1, 101 is a packet type discrimination flag attaching means, 102 is a first-in first-out packet storage means, 103 is a buffer accumulation amount monitoring means, and 104 is a packet discarding means.

  The packet type discrimination flag attaching means 101 attaches a discrimination flag to the packet type based on a predetermined field value such as header information of the input packet, and stores it in the first-in first-out type packet storage means 102. Thereafter, the packets stored in the first-in first-out packet storage means 102 are output in the order in which they are stored.

  When storing in the first-in first-out type packet storage unit 102, the number of stored packets is monitored by the buffer accumulation amount monitoring unit 103. If the first-in first-out type packet storage unit 102 is empty, the stored packet number is stored. The packet discarding unit 104 is notified of the discard signal.

  Upon receiving the discard signal, the packet discarding unit 104 selects and discards the packet specified by a predetermined rule from the packets stored in the first-in first-out packet storage unit 102, and after creating an empty packet type determination flag The packet from the attaching means 101 is stored in the first-in first-out packet storage means 102.

  FIG. 2 is a diagram showing a detailed configuration of the first-in first-out type packet storage means 102. As shown in FIG. 2, the first-in first-out packet storage means 102 includes a descriptor register string in which descriptor registers 201 for storing descriptors are arranged in order, and a packet data storage memory 205 for storing packet data bodies.

  Further, the descriptor register 201 is an address information 204 of a memory area reserved for storing packet data, and an empty space that is set and stored when no packet data is stored in the memory address area. High when the packet data is stored in the flag 202 and its memory address area, and reset when the priority of the stored packet is classified as high priority and not classified as high priority And a priority flag 203.

  In FIG. 2, the descriptor register sequence is ordered so that the right side is the first-in first-out head, a high priority packet is stored in address A of the memory address area, address B is empty, and address C is stored. It is shown that packets that are not high priority are stored.

  FIG. 3 is a diagram for explaining the operation when outputting packet data in the first-in first-out packet storage means 102. When outputting a packet, the packet data stored at address B pointed to by the first descriptor register is read and output, and the empty flag 202 of this descriptor register is set, and the value is copied to the leftmost descriptor register. At the same time, the value of each descriptor register is copied to the descriptor register on the right.

  FIG. 4 is a diagram for explaining the operation when inputting packet data in the first-in first-out packet storage means 102. When a packet is input, the empty flag 202 of the descriptor register on the rightmost of the descriptor registers for which the empty flag in the descriptor register string is set is reset, and the input packet determined by the packet type determination flag attaching means 101 is reset. After setting the priority flag 203 according to the priority, the packet data is written to the address A of the memory address area indicated by the descriptor register.

  Here, FIG. 5 and FIG. 6 show operations when there is no descriptor register for which the empty flag is set in the descriptor register string when a packet is input.

  First, in FIG. 5, a descriptor register in which the priority flag of the descriptor register is reset is specified by means not shown. Here, the leftmost descriptor register 501 is specified among the descriptor registers whose priority flags are reset, the empty flag 202 is set, and the value of the descriptor register is copied to the leftmost descriptor register. At the same time, the value of each descriptor register on the left side of the descriptor register 501 is copied to the descriptor register on the right side.

  As a result, the packet storage area pointed to by the leftmost descriptor register is released, and one packet is empty. Thereafter, the same operation as described in FIG. 4 is performed, but in this case, the descriptor register in which the empty flag is set is only the leftmost descriptor register, so the result of inputting the packet data is as shown in FIG.

  As described above, the packet buffer device according to the present invention inputs two types of packets having different priorities, outputs them after temporarily accumulating them, and outputs them in the input order while the buffer is empty. When a packet is accumulated until it becomes impossible to input a new packet, it has a function to preferentially discard one of the two types of packets stored in the buffer. Is something that can be done.

  As a result, it is necessary to transmit audio and video synchronously, and transmission capacity on an IP network that may occasionally saturate the transmission capacity, for example, an application such as an IP videophone, is normal. Since packets and video packets can be handled with the same priority, the quality of either audio or video will not be degraded, and it will not be difficult to synchronize video and audio. When an unavoidable state is reached, the video packet can be discarded first and the transmission of the audio packet can be maintained as much as possible, so that the communication quality can be maintained.

(Embodiment 2)
FIG. 7 is a block diagram showing a configuration of the packet relay transfer apparatus according to the second embodiment of the present invention. This packet relay transfer apparatus is configured using the packet buffer apparatus according to the first embodiment of the present invention, and performs a packet relay operation from the network 1 to the network 2.

  In FIG. 7, 701 is an input port, 702 is a packet priority discriminating means, 703 is a packet buffer device of the first embodiment, 704 is a first-in first-out packet storage means, 705 is a packet output selecting means, and 706 is an output port. is there.

  Packets input from the network 1 through the input port 701 are given the highest priority, second priority, and third priority in the packet discrimination means 702 according to the value of a predetermined field such as header information of the input packet. It is determined in three stages. Packets determined as the highest priority or the second priority are stored in the packet buffer device 703. Packets determined as the third priority are stored in the first-in first-out packet storage unit 704.

  When a packet is stored in both the packet buffer device 703 and the first-in first-out packet storage unit 704, the packet output selection unit 705 selects the packet stored in the packet buffer device 703 and passes it through the output port 706. When there is no packet in the packet buffer unit 703 and the packet is stored in the first-in first-out type packet storage unit 704, the packet stored in the first-in first-out type packet storage unit 704 is selected. And output to the network 2 through the output port 706.

  In this example, the priority of the input packet determined by the packet determining unit 702 is three levels, but the priority may be four or more levels. In that case, there are a plurality of first-in first-out type packet storage means 704, and packets of the third priority or lower are stored in the respective first-in first-out type packet storage means according to each priority.

  In general, in a packet transmission network that transmits video data and audio data, device control information packets having a relatively low real-time transmission requirement are mixed in addition to video packets and audio packets. Further, in such a packet transmission network, there are often mixed packets such as web browsing packets and e-mail packets that are completely unrelated to video packets and audio packets and have almost no real-time transmission request.

  In such a packet transmission network environment, by using the packet relay / transfer apparatus of the present invention, the priority of the voice packet is set to the highest priority, the priority of the video packet is set to the second priority, and the priority of the other packets is set. By setting the third priority, each packet stored in the packet buffer device and the first-in first-out packet storage means can be selected and output based on the priority, so that the optimum relay transfer can be performed for each packet. It becomes.

(Embodiment 3)
FIG. 8 is a block diagram showing a configuration of a network system according to Embodiment 3 of the present invention. This network system is configured using the packet relay transfer apparatus according to the second embodiment of the present invention.

  In FIG. 8, reference numeral 801 denotes a server device that distributes audio and video to a terminal through a network, 802 denotes audio input means, 803 denotes video input means, 804 denotes audio packetization means, 805 denotes video packetization means, and 806 controls. Protocol execution means, 807 is a network interface, and 808 is a packet relay transfer apparatus according to the second embodiment.

  In the server device 801, the voice data input from the voice input unit 802 is packetized by the voice packetization unit 804. At this time, in accordance with the packet priority determination means of the packet relay transfer device 808, the value of a predetermined field such as packet header information is set. Here, the audio data is set as the highest priority.

  Video data input from the video input unit 803 is packetized by the video packeting unit 805. At this time, in accordance with the packet priority determination means of the packet relay transfer device 808, the value of a predetermined field such as packet header information is set. Here, the video data is set as the second priority.

  The control protocol execution means 806 transmits and receives control information packets for controlling video packets and audio packets and control information packets for controlling devices to and from the delivery destination device, and controls and manages communication.

(Embodiment 4)
FIG. 9 is a block diagram showing a configuration of a network system according to Embodiment 4 of the present invention. The configuration of the network system according to the present embodiment is a configuration in which a priority switching instruction unit 901 is added to the network system according to the third embodiment.

  In the server apparatus 801, the voice data input from the voice input unit 802 is packetized by the voice packetization unit 804. At that time, in accordance with the priority instructed based on the rules preset in the priority switching instruction unit 901 and in accordance with the packet priority determination means of the packet relay transfer device 808, the header information of the packet such as the header information of the packet Set the value.

  Video data input from the video input means 803 is packetized by the video packetization means 805. At that time, in accordance with the priority instructed based on the rules preset in the priority switching instruction unit 901 and in accordance with the packet priority determination means of the packet relay transfer device 808, the header information of the packet such as the header information of the packet Set the value.

  Here, the priority instruction given from the priority switching instruction unit 901 to the audio packetization means 804 and the priority instruction given to the video packetization means 805 are instructions for alternately switching the priority, and one of them is the highest priority. In the case of degree, the other has the second priority, and the priority of one of the packets is always higher.

  The packet buffer device, the packet relay transfer device, and the network system of the present invention normally handle either the audio packet or the video packet by handling the audio packet and the video packet with the same priority when transmitting the audio packet and the video packet at the same time. If there is no deterioration in quality or it becomes difficult to synchronize the video and audio, and if the buffer overflow is unavoidable due to an abnormal transmission system, the video packet is discarded first and the audio packet is as much as possible. By maintaining the transmission, the communication quality can be maintained and used when packetizing and distributing audio data and video data together with control information on a packet communication network such as an IP network. Packet buffer device, packet relay transfer device, and network system As useful.

1 is a block diagram showing a configuration of a packet buffer device according to Embodiment 1 of the present invention. The figure which shows the detailed structure of the first-in first-out type packet storage means in the packet buffer apparatus concerning Embodiment 1 of this invention. The figure which shows the output operation | movement of the packet data in a first-in first-out type packet memory means. The figure which shows the input operation | movement of the packet data in a first-in first-out type packet memory means. The figure which shows operation | movement when there is no empty of a descriptor register at the time of packet input. The figure which shows the operation | movement after making empty of a descriptor register at the time of packet input. The block diagram which shows the structure of the packet relay transfer apparatus which concerns on Embodiment 2 of this invention. The block diagram which shows the structure of the network system which concerns on Embodiment 3 of this invention. The block diagram which shows the structure of the network system which concerns on Embodiment 4 of this invention.

Explanation of symbols

101 packet type discrimination flag attaching means 102 first-in first-out type packet storage means 103 buffer accumulation amount monitoring means 104 packet discard means 201, 501 descriptor register 202 empty flag 203 high priority flag 204 packet data storage address 205 packet data storage memory 701 input port 702 Packet priority determination means 703 Packet buffer device 704 First-in first-out packet storage means 705 Packet output selection means 706 Output port 801 Server device 802 Audio input means 803 Video input means 804 Audio packetization means 805 Video packetization means 806 Control protocol execution means 807 Network interface 808 Packet relay and transfer device 901 Priority switching instruction section

Claims (9)

  Packet type discrimination flagging means for adding a flag corresponding to the type of the packet input from the input port to the packet, and storing the flag flagged by the packet type discrimination flag addition means and outputting to the output port by first-in first-out First-in first-out packet storage means, buffer storage amount monitoring means for monitoring the amount of packets stored in the packet storage means, and the buffer storage amount monitoring means detects that the packet storage means is empty A packet buffer device comprising: a packet discard unit that receives a packet discard signal output when the packet is received and discards a specific type of packet preferentially from the packet storage unit.   The packet storage means includes a descriptor string holding means for storing a plurality of descriptors describing packet control information in order and a memory for storing packets. The packet control information described by the descriptor includes A memory address specifying the storage area, an empty flag indicating whether or not the packet storage area specified by the address is in an empty state in which no packet is stored, and a packet storage area specified by the address 2. The packet buffer device according to claim 1, further comprising a high priority flag for indicating whether or not the stored packet has a high priority.   The packet storage means reads the packet stored in the storage area at the memory address specified by the first descriptor of the ordered descriptor string, changes the empty flag of the descriptor to an empty display, and The packet buffer device according to claim 2, wherein the order of descriptors other than the descriptor in the ordered descriptor sequence is increased by one by one.   The packet storage means writes a packet to the storage area at the memory address designated by the descriptor having the highest rank among the descriptors for which the empty flag indicates an empty state in the ordered descriptor string, and Change the flag to a non-empty display, set the descriptor's high priority flag according to the priority of the input packet, lower the descriptor's rank to the end of the ordered descriptor string, and If the rank of the descriptor lower than the rank of the descriptor in the descriptor column is incremented by one, and there is no descriptor whose empty flag indicates an empty state in the ordered descriptor column, the ordered descriptor High priority in the column Write the packet to the storage area at the memory address specified by the descriptor specified by the predetermined rule among the descriptors indicating that the lag is not high priority, and change the descriptor's empty flag to a non-empty display. The descriptor high priority flag is set according to the priority of the input packet, the descriptor rank is lowered to the end of the ordered descriptor string, and the descriptor rank in the ordered descriptor string 3. The packet buffer device according to claim 2, wherein the rank of the lower descriptor is increased by one.   5. The packet buffer device according to claim 4, wherein the predetermined rule specifies a descriptor having the lowest rank among the descriptors indicating that the high priority flag is not high priority in the ordered descriptor string. .   The packet buffer device according to any one of claims 1 to 5, one or more first-in first-out type packet storage means, packet priority determination means for determining the priority of an input packet in three or more stages, A packet output selection means for selecting and outputting a packet stored in the packet buffer device or the first-in first-out packet storage means, and the packet priority determination means includes a highest priority or a second priority. The determined packet is input to the packet buffer device, the packet determined to be lower than the third priority is input to the first-in first-out type packet storage means, and the packet output selection means is configured to send a packet to the packet buffer device. Is stored, the packet stored in the packet buffer device is selected and output, and the packet is stored in the packet buffer device. Packet relay transfer device for selecting and outputting the packets stored in the FIFO type packet memory means when Tsu bets is not stored.   7. A packet relay / transfer apparatus according to claim 6, comprising: audio input means; video input means; packetization means for packetizing input audio data and video data and adding packet priority information to each packet; Network system.   The packetizing means packetizes the audio data by adding information that the packet relay transfer device determines as the highest priority, and adds the information that determines the video data as the second priority by the packet relay transfer device. The network system according to claim 7, wherein the network system is packetized.   Priority switching instruction means for instructing switching of priority information to be added to a packet, and the packetizing means packetizes the audio data by adding information that the packet relay transfer device determines as the highest priority. An operation for packetizing data by adding information that the packet relay transfer device determines as a second priority, and a packetizing video data by adding information that the packet relay transfer device determines as a second priority 8. The network system according to claim 7, wherein the packet relaying / transferring apparatus switches the data packeting operation by adding information for determining that the packet relaying / transferring apparatus has the highest priority according to an instruction from the priority switching instruction means.

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