JP4063120B2 - Packet transmission equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a packet transmission apparatus that performs communication in a packet communication network such as the Internet in the communication field, and more particularly to a technique for efficiently distributing content in a packet communication network.
[0002]
[Prior art]
Conventionally, when content such as video is distributed to viewers using a network such as the Internet, centralized distribution in which content is directly distributed to each viewer from one or a few video servers has been mainstream. However, in this mode, the video server needs to transmit the content by the number of viewers. Therefore, when the number of viewers is very large, the video server has a high performance for transmitting a large number of streams simultaneously. There is a problem that the distribution cost becomes high.
[0003]
Therefore, in recent years, a “bucket relay type” content distribution technology that applies peer-to-peer technology has been proposed (see, for example, Non-Patent Document 1). FIG. 8 shows the concept of a bucket relay type content distribution system.
[0004]
In FIG. 8, reference numeral 810 denotes a video server that is a distribution source of content including video and audio (hereinafter referred to as video content). Reference numerals 811 to 815 denote terminal devices for viewing content, which are actually realized by a personal computer, a network-compatible television, or the like. When distributing video content in the system of FIG. 8, the video server 810 first distributes content to a small number of terminal devices 811 and 812 via the communication network 820 or the like. The terminal devices 811 and 812 transmit video content being received to other terminal devices at the same time while viewing the video content themselves. For example, the terminal device 811 transmits to another terminal device 813 to 815.
[0005]
Thus, by transmitting video content from the terminal device to the terminal device in a bucket relay manner, the video server 810 does not require high performance as in the case of centralized distribution, and content to a large number of terminal devices. Distribution becomes possible, and the distribution cost can be reduced as compared with the centralized distribution form.
[0006]
FIG. 9 is a diagram illustrating a configuration of a terminal device using a conventional packet transmission device described in Non-Patent Document 1. In FIG. 9, 9 is a conventional packet transmission apparatus. Reference numeral 910 denotes a processor such as a CPU, and reference numerals 210, 211, 912, and 913 denote processes executed by the processor software. The data packet including the video content (the Ethernet frame in this example) is received by the Ethernet (R) frame reception processing unit 101 and passed to the processor 910.
[0007]
The IP protocol reception processing unit 210 in the processor 910 extracts the data in the payload portion from the data packet and passes it to the data reception application 912. In the video application 912, video content data is extracted from the payload data, decoded by the AV decoder 220, and displayed on the screen by the display device 221 such as a display.
[0008]
At the same time, the data in the payload part is passed to the data transmission application 913, converted into a transmission packet by the IP protocol transmission processing unit 211, transmitted by the Ethernet (R) frame transmission unit 107, and other terminal devices via the communication network. Is transmitted.
[0009]
[Non-Patent Document 1]
Bit Media Co., Ltd., Uncle Co., “Sharecast Architecture”, “online”, February 2002, “February 27, 2003 Search”, Internet <URL: http: // www. scast. tv / sca. pdf>
[0010]
[Problems to be solved by the invention]
However, when “bucket relay distribution” is performed by a terminal device having the above-described conventional configuration, video content transfer in each terminal device needs to be performed by software processing by a processor. As compared with the case of only the case, the processing performance is about twice as high. For this reason, a high-performance processor is required, and there is a problem that the cost of the terminal device increases.
[0011]
The present invention solves the above-mentioned conventional problems, and transfers data packets by hardware in order to enable “bucket relay distribution” even in a terminal device using an inexpensive processor with low performance. An object of the present invention is to provide a packet transmission apparatus capable of
[0012]
[Means for Solving the Problems]
In order to solve the conventional problem, a packet transmission apparatus according to the present invention includes a packet receiving unit that receives a packet including address information, and an address that stores received address information and transfer address information associated with the received address information. A correspondence table; a means for determining whether the address information of the received packet received by the packet receiving means matches any of the received address information registered in the address correspondence table; and the address of the received packet Address rewriting means for rewriting information according to the forwarding address information associated with the received address information matched in the address correspondence table, means for transmitting the packet output by the address rewriting means, and measuring the reception time of the received packet Receiving time measurement hand Transfer time calculating means for obtaining the transfer time of the received packet based on the reception time; transfer control means for controlling transmission of the received packet according to the transfer time; means for measuring a burst interval of the received packet; The transfer time is a value based on the burst interval.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0014]
FIG. 1 is a schematic configuration diagram of a packet transmission apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of a terminal device using the apparatus.
[0015]
FIG. 3 is a diagram showing the structure of an Ethernet (R) frame that is a data packet received or transmitted by the apparatus. In FIG. 3, the Ethernet (R) frame 30 has three types of headers: an Ethernet (R) header 310, an IP header 320, and a UDP header 330. In addition, it has a transferable number counter field 323 that represents the remaining number of times that a packet can be transferred, and the video server sets the maximum number of times that a packet can be transferred by a terminal device.
[0016]
FIG. 4 shows the data structure stored in the address correspondence table 109 in FIG. The address correspondence table 109 includes a reception address information table 41 and a transfer address information table 42. The reception address information table 41 stores information necessary for receiving data packets that need to be transferred to other terminal devices. . The transfer address information table 42 stores information necessary for transferring the received packet to another terminal device. Further, each address information in the received address information table stores a correspondence of corresponding transfer address information.
[0017]
Next, the operation of the packet transmission apparatus according to the first embodiment of the present invention will be described using FIGS. 1 to 4 with reference to the operation flow of FIG.
[0018]
First, FIG. 5A shows a procedure for receiving video content directly from a video server. When an operator of the terminal device requests to start viewing, the data reception application 211 of the terminal device sends information about its own IP address and video content reception port number (UDP protocol port number) to the video server. A transmission request is sent to the server (step 501). However, at this time, it is assumed that the terminal device knows the IP address of the video server in advance.
[0019]
If the requested content can be transmitted, the video server returns “success” to the terminal device. When the terminal device receives “success” (procedure 502), it starts receiving a packet containing video content (procedure 503). The Ethernet (R) frame reception processing unit 101 in FIG. 1 receives an Ethernet (R) frame that is a data packet transmitted from the video server, and passes it to the processor 21 in FIG. 2 through the packet output port 112.
[0020]
In FIG. 2, 210, 211 and 212 are executed by software by a processor. The IP protocol reception processing unit 210 processes the IP header and the UDP header of the received Ethernet (R) frame 30, extracts the payload 340, and passes it to the data reception application 211. The data reception application 211 passes the video content data included in the payload to the AV decoder 220. This data is decoded by the AV decoder 220 and displayed on the screen by a display device 221 such as a display.
[0021]
Next, a case where a transfer request is received from another terminal device while receiving video content from the video server will be described with reference to the flowcharts of FIGS. 5B and 5C.
[0022]
When receiving a transfer request from another terminal, the transfer control application 212 in FIG. 2 acquires the IP address of the partner terminal and the port number received by the partner terminal from the partner terminal (step 511 in FIG. 5). The transfer control application 212 sets the reception address information and the transfer address information as shown in FIG. 4 in the reception address information table 41 and the transfer address information table 42 of the address correspondence table 109 in FIG. 1 (procedure 512). . In the example of FIG. 4, it is assumed that the transmission source port number in the reception address information table 41 is unknown until a packet including video content is received from the video server, and a value indicating “arbitrary” is set. .
[0023]
In addition, in the “forwarding address information number” field of the item 401 of the reception address information table 41, 410, which is the number of the corresponding forwarding address information table item, is set and associated with each other.
[0024]
When the Ethernet frame reception processing unit 101 receives an Ethernet frame after completing the setting of the address correspondence table by the above procedure (procedure 521), it is passed to the processor 21 via the packet output port 112, and the reception time measurement unit 102 receives the reception time. The measurement is performed (procedure 522), and the transfer time calculation processing unit 108 calculates the transfer time, which is the time to be transferred, according to the procedure described later (procedure 523).
[0025]
Subsequently, the address determination processing unit 103 refers to the reception address information table of the address correspondence table 109 to determine whether each item of the table matches the corresponding item of the received Ethernet frame (procedure 524). In this example, since a value indicating “arbitrary” is written in the transmission source port number of the reception address information table, the corresponding item is not used for determination of coincidence / non-coincidence.
[0026]
If the address determination processing unit 103 determines “match”, the Ethernet (R) frame is transferred to the transferable number counter processing unit 104 and whether or not the value of the transferable number counter field 323 of the data packet 30 is 1 or more. (Procedure 525). If the value of the transferable number counter field 323 is 0, the Ethernet frame is discarded.
[0027]
When the value of the transferable number counter field 323 is 1 or more, the transferable number counter processing unit 104 rewrites the value of the transferable number counter field 323 by 1 (step 526), and the address rewrite processing unit 105. To the Ethernet (R) frame. The address rewrite processing unit 105 refers to the address correspondence table 109, acquires transfer address information 410 corresponding to the received address information 401 of the Ethernet (R) frame (step 527), and transmits the destination IP address included in the Ethernet frame, the transmission The values of the source IP address, destination port number, and source port number fields are rewritten to the values indicated by the transfer address information 410 (procedure 528). The rewritten data packet is waited until the “transfer time” obtained by the transfer time calculation unit 108 in the transfer control unit 106 (procedure 529), and then transmitted from the Ethernet (R) frame transmission processing unit (procedure). 530).
[0028]
In this way, even in a bucket relay type content distribution method in which a terminal device receives a data packet and transfers it to another terminal device, the processor does not need to perform packet transfer processing and only receives processing. Since the processing load is about the same, a terminal device that supports bucket relay distribution can be realized even with an inexpensive processor with low performance.
[0029]
Furthermore, in the bucket relay type distribution method, there is a possibility that a “loop” occurs in which the data packet transferred by itself returns to itself via another terminal device. Unless one of the terminal devices stops communication, there is a problem that the packet continues to flow infinitely in the loop and increases the load on the network. In response to this problem, a transferable number counter field 323 indicating the number of times a packet can be transferred is provided, and when the video server transmits, a maximum transferable value is set, and the terminal device that has received the packet receives another terminal. Each time the packet is transferred to the device, the value of the transferable count counter field 323 is decreased by 1, and when the field becomes 0, no further transfer is performed. The number of flows can be limited to a finite number of times, and the load on the network can be suppressed.
[0030]
In the embodiment of the present invention described above, each item of the reception address information table and the transfer address information table shown in FIG. 4 has been described as one item, but each table stores a plurality of items. It is also possible. When multiple items are registered in the received address information table, if the received packet matches any of the registered received address information, transfer is performed according to the contents of the transfer address information table associated with the received address information. Is called.
[0031]
It is also possible to register multiple items in the forwarding address information table to be associated with each item in the receiving address information table. In this case, the received packet is forwarded to all the forwarding destinations in the plurality of items in the associated forwarding address information table. To do.
[0032]
Next, a procedure for obtaining the time (transfer time) at which the received packet should be transferred in the transfer time calculation processing unit 108 will be described with reference to FIGS. 6 and 7.
[0033]
In the case of bucket relay distribution, the terminal device sends back the transfer packet to the same network as the communication network (for example, 120) that received the packet. As shown in FIG. 6 (a), data packets sent from the video server are generally not uniform in packet transmission timing, and a plurality of packets are sent together in a burst (in a burst manner). If the packet is transferred immediately, the received packet and the transferred packet collide with each other, which may reduce the transmission efficiency. In addition, since the IP router to which the terminal device is connected needs to process the received packet and the transmitted packet at the same time, the peak load increases and the IP router may not be able to transfer sufficiently. In order to avoid this, it is effective to prevent the transfer to other terminal devices from overlapping the timing of the received packet.
[0034]
FIG. 7 is a schematic configuration diagram of an embodiment of the transfer time calculation processing unit 108.
[0035]
In FIG. 7, the burst determination processing unit 1081 determines the burst period based on the reception time information of each packet input from the reception time measurement processing unit 102. The burst period can be determined, for example, as a period in which the reception interval of each packet is equal to or less than a predetermined value determined in advance.
[0036]
Furthermore, the burst determination unit 1081 obtains a burst length 611 that is the length of the burst period and a burst interval 612 that is an interval from the immediately preceding burst period in each burst period. The filter means 1082 calculates an average value of the past N times (N is a predetermined value) of the burst length and burst interval values for each burst period. The waiting time calculation processing unit 1084 uses the output of the burst length measurement processing unit 1081 or the value output by the filter unit 1082 to obtain the time to wait before transferring each data packet.
[0037]
Various methods can be used as the procedure for obtaining the waiting time. For example, the method can be obtained by the following procedure.
[0038]
Example 1) A value obtained by adding a predetermined fixed time to an average burst length.
[0039]
Example 2) A value obtained by multiplying an average value of burst intervals by a predetermined ratio (for example, 0.5).
[0040]
In the above-described embodiment, the filter means calculates the average value of the past N times, but the same effect can be obtained even if other filter means are used.
[0041]
【The invention's effect】
As described above, according to the packet transmission apparatus of the present invention, the processor of the terminal device only needs to perform the reception process even in the case of supporting the bucket relay distribution system capable of distributing content to a large number of viewers. Therefore, even when the processor capacity is low, it is possible to provide a terminal device that supports the bucket relay distribution system.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a packet transmission apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a terminal device using the packet transmission apparatus according to an embodiment of the present invention. FIG. 4 is a diagram illustrating an example of information stored in an address correspondence table. FIG. 5 is a flowchart illustrating an operation of the packet transmission apparatus according to the embodiment of the present invention. FIG. 7 is a schematic configuration diagram of a transfer time calculation processing unit in the embodiment of the present invention. FIG. 8 is a schematic diagram of a conventional packet transmission device. Configuration diagram and schematic configuration diagram of terminal equipment using the same device [FIG. 9] Conceptual diagram of bucket relay type distribution system [Explanation of symbols]
1 packet transmission device 101 Ethernet frame reception processing unit 102 reception time measurement processing unit 103 address determination processing unit 104 transferable number counter processing unit 105 address rewrite processing unit 106 transfer control unit 107 Ethernet (R) frame transmission processing unit 108 transfer time calculation Processing unit 109 Address correspondence table 120 Ethernet (R) input / output terminal 121 Packet input port 122 Packet output port 123 Address correspondence table setting port 2 Terminal device 21 Processor 210 IP protocol reception processing unit 211 Data reception application 220 AV decoder 221 Display processing unit 30 Data packet 310 Ethernet header 311 Destination Ethernet address 312 Source Ethernet address 320 IP header 321 Destination IP address 322 Source IP address 330 UDP header 331 Destination port number 332 Source port number 323 Transferable number counter 340 Payload 41 Receive address information table 42 Transfer address information table 61 Receive packet 62 Transfer packet 611 Burst length 612 Burst interval 613 Transfer waiting time 1081 Burst determination processing unit 1082 Filter means 1083 Selection switch 1084 Transfer waiting time calculation processing unit 1085 Adder 810 Video server 811, 812, 813, 814, 815 Terminal equipment 820, 821 Communication network 9 Conventional packet transmission device 910 Processor 211 IP protocol transmission processing unit 912 Data reception application 913 Data transmission application

Claims (2)

A packet receiving means for receiving a packet including address information;
An address correspondence table for storing reception address information and transfer address information associated with the reception address information;
Means for determining whether address information of a received packet received by the packet receiving means matches any of the received address information registered in the address correspondence table;
Address rewriting means for rewriting the address information of the received packet according to the forwarding address information associated with the received address information matched in the address correspondence table;
Means for transmitting a packet output by the address rewriting means;
A reception time measuring means for measuring the reception time of the received packet;
A transfer time calculating means for obtaining a transfer time of the received packet based on the reception time;
Transfer control means for controlling transmission of the received packet according to the transfer time;
Means for measuring a burst interval of the received packet,
The packet transmission apparatus, wherein the transfer time is a value based on the burst interval. A packet receiving means for receiving a packet including address information;
An address correspondence table for storing reception address information and transfer address information associated with the reception address information;
Means for determining whether address information of a received packet received by the packet receiving means matches any of the received address information registered in the address correspondence table;
Address rewriting means for rewriting the address information of the received packet according to the forwarding address information associated with the received address information matched in the address correspondence table;
Means for transmitting a packet output by the address rewriting means;
A reception time measuring means for measuring the reception time of the received packet;
A transfer time calculating means for obtaining a transfer time of the received packet based on the reception time;
Transfer control means for controlling transmission of the received packet according to the transfer time;
Means for measuring the burst length of the received packet,
The packet transmission apparatus, wherein the transfer time is a value based on the burst length.

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