JP2009071462A - Communication apparatus, communication system, and communication control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a router in IP communication, improved in reliability. <P>SOLUTION: A communication apparatus which carries out IP processing for packets from one IP transmission route by an IP processing unit 15, and transmits them to other IP transmission routes, includes: a division/restoration determination processing unit 14 which determines whether to divide the packets from the IP processing unit 15 based on the maximum packet size which is transmittable by the other transmission routes, and simultaneously determines whether to restore the divided packets from the IP processing unit 15; and a packet division/restoration unit 16 which divides the packets and simultaneously generates redundancy packets of the divided packets when the division/restoration determination processing unit 14 determines packet division, and restores the divided packets and send them to the IP processing unit 15 when it determines packet restoration. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication apparatus, a communication system, and a communication control method, and more particularly to a packet division and restoration method when IP packet communication is performed between a source host and a destination host in an IP network.

  An IP (Internet Protocol) network is composed of various transmission paths such as Ethernet (registered trademark), ADSL (Asymmetric Digital Subscriber Line), and optical fiber. Each of these transmission paths has an upper limit value of the packet size that can be transmitted, and this value is called MTU (Maximum Transmission Unit).

  The following techniques are related to the present invention. When the source host performs IP communication with the destination host, if a packet is transmitted without considering the MTU of each transmission path between the source host and the destination host, the router in the middle of the path When a packet exceeding the MTU of the transmission path to be used next for relay is received, the packet received by the IP processing unit of the router is divided and transmitted so as to have a size equal to or smaller than the MTU. The IP processing unit of the destination host restores the original packet (see Patent Documents 1 and 2).

JP 2003-209577 A JP 2007-129452 A

  The first problem in the related art described above is that the success rate of communication may decrease when the packet division function by IP processing is used. The reason for this is that when one packet is transmitted once and when it is divided and transmitted multiple times, it is more congested on the network and on the wireless transmission path when divided and transmitted multiple times. Since there are many opportunities for packet loss due to transmission path errors and so on, the probability that all divided packets can be received decreases. This is because the IP packet division function does not have a function for ensuring reliability, such as correcting an error, and a lost packet is not recovered.

  In addition, the second problem of the related technology is that in IPv6 (Internet Protocol version 6), a division restoration function must be prepared for each transmission path, and a dedicated network composed of various transmission paths is constructed. This means that the scale of development will increase. The reason for this is that the function for dividing packets in the IP processing unit of the router in the middle of the route is not provided in IPv6, so the functions for dividing and restoring packets are implemented in the protocol layer below IP. This is because it must be done.

  An object of the present invention is to provide a communication apparatus, a communication system, a communication control method, and a program thereof in IP communication that can improve reliability.

  Another object of the present invention is to provide a communication apparatus, a communication system, a communication control method, and a program thereof in IP communication that can improve development efficiency even in the construction of a network using IPv6.

  A communication apparatus according to the present invention is a communication apparatus that performs IP processing on a packet from one IP transmission path by an IP unit and transmits the packet to another IP transmission path, and transmits the packet from the IP unit to the other A division determination unit that determines whether or not to divide based on the maximum packet size that can be transmitted on the transmission line, and when the division determination unit determines to divide the packet, Dividing means for generating a redundant packet and deriving it to the IP means.

  Another communication apparatus according to the present invention is divided based on the maximum packet size that can be transmitted on the IP transmission path, and receives the redundant packet of the divided packet from the transmission path together with the divided packet and the redundant packet. A communication apparatus that performs IP processing by means and transmits to another IP transmission path, and that determines whether or not a fragmented packet from the IP means should be restored, and should be restored by the restoration judgment means A packet restoring means for performing packet restoration based on the divided packet and the redundant packet and deriving the packet to the IP means.

  Still another communication apparatus according to the present invention is a communication apparatus that performs IP processing on a packet from one IP transmission path by an IP unit and transmits the packet to another IP transmission path, and transmits the packet from the IP unit. Determining whether or not to divide based on the maximum transmittable packet size of the other transmission path, and determining whether or not to recover the divided packet from the IP means; and When it is determined by the division / restoration determination means that the packet should be divided, the packet is divided and a redundant packet of the divided packet is generated. When the division / restoration determination means determines that the packet is to be restored, Packet division / restoration means for restoring the fragmented packet and deriving it to the IP means.

  A communication system according to the present invention includes the above-described communication devices.

  A communication control method according to the present invention is an operation control method in a communication apparatus that performs IP processing on a packet from one IP transmission path by an IP unit and transmits the packet to another IP transmission path. A division determination step for determining whether or not to divide a packet based on the maximum transmittable packet size of the other transmission path; and when the division determination step determines that the packet should be divided, the packet is divided And a dividing step of generating a redundant packet of the divided packet and deriving it to the IP means.

  Another communication control method according to the present invention is divided based on the maximum transmittable packet size of the IP transmission path, and received from the transmission path together with the redundant packet of the divided packet, and the divided packet and the redundant packet are An operation control method in a communication apparatus that performs IP processing by IP means and transmits to another IP transmission path, a restoration determination step for determining whether or not to restore a fragmented packet from the IP means, and the restoration determination A packet restoring step of performing packet restoration based on the divided packet and the redundant packet and deriving the packet to the IP means when it is determined that the restoration is to be performed by the step.

  Still another communication control method according to the present invention is an operation control method in a communication apparatus that performs IP processing on a packet from one IP transmission path by IP means and transmits the packet to another IP transmission path. Determining whether or not the packet from the means should be divided based on the maximum transmittable packet size of the other transmission path, and determining whether or not to restore the divided packet from the IP means When it is determined in the determination step and the division / restoration determination step that the packet is to be divided, the packet is divided, a redundant packet of the divided packet is generated, and the packet is to be restored in the division / restoration determination step. A packet fragmentation / restoration step of restoring the fragmented packet and deriving the fragmented packet to the IP means when it is determined.

  A program according to the present invention is a program for causing a computer to execute an operation control method in a communication apparatus that performs IP processing on a packet from one IP transmission path and transmits the packet to another IP transmission path. A process for determining whether to divide a packet from the process based on the maximum transmittable packet size of the other transmission path, and a packet division when it is determined by the division determination process that the packet should be divided And a dividing process for generating a redundant packet of the divided packet and deriving it to the IP process.

  Another program according to the present invention is divided based on the maximum packet size that can be transmitted on the IP transmission path, and received from the transmission path together with the redundant packet of the divided packet, and IP processing is performed on the divided packet and the redundant packet. Is a program for causing a computer to execute an operation control method in a communication apparatus that performs transmission to another IP transmission path, and a restoration determination process that determines whether or not to restore a fragmented packet from the IP process; A packet restoration step of performing packet restoration based on the divided packet and the redundant packet and deriving the packet to the IP process when it is determined that the restoration should be restored by the restoration judgment process.

  Still another program according to the present invention is a program for causing a computer to execute an operation control method in a communication apparatus that performs IP processing on a packet from one IP transmission path and transmits the packet to another IP transmission path. Determining whether or not the packet from the IP processing should be divided based on the maximum packet size that can be transmitted on the other transmission path, and determining whether or not the divided packet from the IP processing should be restored When it is determined to be divided by the division / restoration determination process and the division / restoration determination process, the packet is divided and a redundant packet of the divided packet is generated, and is restored by the division / restoration determination step. A packet fragmentation / restoration process for restoring the fragmented packet and deriving it to the IP process. To.

  The first effect of the present invention is that reliability can be improved even if packet division is performed. The reason is that, at the time of packet restoration, even if there is a loss in the divided packets, a decrease in the success rate of communication can be suppressed by transmitting redundant packets for error correction.

  The second effect of the present invention is that the development scale can be reduced even when a dedicated network configured by various transmission paths using IPv6 is constructed. This is because a common packet division and restoration function can be prepared for each transmission path. As a result, the development scale can be reduced even when a dedicated network consisting of various transmission paths is constructed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, an example of an IP network to which an embodiment of the present invention is applied is shown. This IP network includes hosts 1 and 2, routers 3 and 4 as communication devices, and transmission paths 5 to 7. Hosts 1 and 2 have a function of performing IP communication between these hosts. Each of the routers 3 to 4 has a function of transferring a packet to an appropriate transmission path according to the destination information of the packet received via the connected transmission path.

  The transmission lines 5 to 7 each have the above-described MTU. The MTUs of the transmission lines 5 and 7 are m [bytes], the MTU of the transmission line 6 is n [bytes], and m> n. .

  FIG. 2 illustrates an outline of the communication protocol configuration of the routers 3 and 4 in the embodiment of the present invention. The router includes an IP 15, a communication AP (Application) transfer layer 14, transmission path interfaces 11 to 12, a communication AP 16, a UDP (User Datagram Protocol) 15, and a communication AP interface 13.

  The communication AP transfer layer 14 transfers packets between the IP 15 and the transmission path interfaces 11 to 12 or the communication AP interface 13 and determines whether or not the packet received from the IP 15 needs to be divided or restored. Sometimes, it has a function of passing a packet to the communication AP 16 via the communication AP interface 13.

  The communication AP interface 13 has a function of transferring a packet between the communication AP 16 and the IP 15 via the communication AP transfer layer 14. The communication AP 16 has a function of dividing a packet exceeding the MTU or restoring a packet divided by the communication AP in another router.

  Although the configuration of the embodiment has been described in detail above, the other protocols and the like shown in FIG. 2 are well known to those skilled in the art and are not directly related to the present invention. Shall.

  Next, the operation of the embodiment of the present invention will be described. Now, in FIG. 1, when the host 1 transmits a packet of size m to the host 2, the outline of the packet division processing in the router 3 (FIG. 3) and the packet restoration processing in the router 4 The outline (FIG. 5) will be described.

  FIG. 3 is a flow of the dividing process (dotted line 100) for showing an outline of the packet dividing process in the router 3. When the router 3 receives the packet addressed to the host 2, the packet is transferred from the transmission path interface 11 for the transmission path 5 to the communication AP transfer layer 14. In the communication AP transfer layer 14, all packets received from the transmission path interface 11 are transferred to the IP 15.

  In IP 15, it is determined from the destination information of the packet that transfer to the transmission path 6 is necessary, and a request for delivering the packet to the transmission path interface for the transmission path 6 is made via the communication AP transfer layer 14. In the communication AP transfer layer 14, the size (m) of the received packet is compared with the size of the MTU (n) of the transmission path 6. In this case, since m> n, the packet is delivered to the communication AP 16 via the communication AP interface 13 in order to cause the packet to be divided. In the communication AP interface 13, all packets received from the communication AP transfer layer 14 are transferred to the communication AP 16.

  The communication AP 16 divides the packet and transmits the divided packet using the UDP / IP service. Therefore, when the packet is divided, as shown in FIG. 4, considering that the header of communication AP, UDP, and IP is added to the divided packet, the packet size is set to n or less. Divide into

  Further, the redundant message shown in FIG. 4 is also generated so that the original packet can be restored even if a part of the packet divided during the communication is lost. This redundant message uses a copy of each divided packet. Finally, information necessary for restoring the original packet is added to the divided packet and redundant message as a communication AP header, and a transmission request is made to the UDP 17 with the destination information in the packet before the division as the destination. Become.

  In the UDP 17 and the IP 15, a header is added to each of the received divided packets and the like, and a request for delivering the packet to the transmission path interface 12 for the transmission path 6 is made via the communication AP transfer layer 14. In the communication AP transfer layer 14, since the size of the received packet is n or less, the packet is transferred to the transmission path interface 12 for the transmission path 6. The transmission path interface 12 for the transmission path 6 sequentially transfers the received packets to the router 4 via the transmission path 6.

  FIG. 5 is a flow of division processing (dotted line 200) for showing an outline of packet restoration processing in the router 4. When the router 4 receives the packet addressed to the host 2, similarly to the processing of the router 3, the transmission path interface 12 for the transmission path 6, the communication AP transfer layer 14, and the IP 15 are sequentially transferred and processed.

  In the communication AP transfer layer 14, when the communication AP header is added to the received packet and it is confirmed by the destination information of the packet that the destination host 2 is directly connected to itself (router 4), The packet is delivered to the communication AP 16 via the communication AP interface 13 in order to perform a packet restoration process.

  Similarly to the processing of the previous router 3, when the communication AP header 13 is given a communication AP header and a divided packet restoration request is received via the communication AP interface 13, the packet or redundant message divided by the router 3 is received. Wait for reception, and when all the packets necessary for restoration are received, restore the original packets. The restored packet is delivered to the IP 15 via the communication AP interface 13 and the communication AP transfer layer 14.

  In the communication AP interface 13, all packets received from the communication AP 16 are transferred to the communication AP transfer layer 14. In the communication AP transfer layer 14, all packets received from the communication AP interface 13 are transferred to the IP 15. In the IP 15, as in the processing of the router 3, a request is made to transfer the packet to the communication AP transfer layer 14 to the transmission path interface 18 for the transmission path 7.

  When the communication AP transfer layer 14 confirms that there is no communication AP header and that the packet size (m) is no problem compared to the MTU (m) of the transmission path 7, the transmission path interface 18 for the transmission path 7 is used. Deliver the packet to In the transmission path interface 18 for the transmission path 7, the received packet is transmitted to the host 2 via the transmission path 7, and the host 2 receives the packet.

  Next, the flow of processing operations in the communication AP transfer layer 14 of FIG. 2 will be described using the flowchart of FIG. First, in step A1, it is determined whether or not a packet is received from IP15. If the packet is received from other than IP15, the packet is transmitted to IP15. If received from IP15, the process proceeds to step A2.

  In step A2, it is confirmed whether or not the header of the communication AP 16 is attached to the packet. If it is given, the process proceeds to step A3. If not, the process proceeds to step A4. In step A3, it is confirmed from the packet destination whether the destination host is directly connected to its own router. If the host is directly connected, it is necessary to restore the packet. If the request for restoration is made to the communication AP via the connection, and the direct connection is not established, the process proceeds to step A4.

  In Step A4, the MTU of the transmission path interface is compared with the packet size. If the packet size is smaller than the MTU, the process proceeds to Step A5. If larger than the MTU, the process proceeds to the communication AP 16 via the communication AP interface 13. A split request is made and the MTU is notified. In step A4, the packet for which the restoration request has been made to the communication AP 16 is a sequential number in the order of packet reception and the combination of the packet source and destination so that the transmission order of the packet received later is not changed. A number (packet ID) to be managed separately is assigned, and this packet ID is used in step A5, and the information is also passed when a division request is made to the communication AP.

  However, if the transmission source is itself among the packets to which the communication AP header is attached, the packet ID set in the communication AP header is used because it is a packet for which a division restoration request has been made previously. .

  In step A5, the packet ID is confirmed, whether the packet having the previous number has been transmitted is confirmed by the packet transmission history managed separately according to the combination of the transmission source and the destination. Send to transmission line interface. At that time, the packet transmission history is updated. If it has not been transmitted yet, it waits for packet transmission.

  Next, the flow of processing operations of the communication AP interface 13 of FIG. 2 will be described using the flowchart of FIG. First, in step B1, it is confirmed from where the packet is received. If the transmission source is IP15, the packet is transmitted to the communication AP 16, and if it is the communication AP 16, it is transmitted to the IP 15 via the communication AP transfer layer 14. To do.

  Next, the flow of processing operations in the communication AP 16 of FIG. 2 will be described using the flowchart of FIG. First, in step C1, the processing request content of the received packet is confirmed. If it is a division request, the process proceeds to step C2, and if it is a restoration request, the process proceeds to step C4. In step C2, the packet is divided below the MTU notified from the communication AP transfer layer. However, when the packet is divided, it is assumed that headers of communication AP, UDP, and IP are added. Note that the packet ID notified from the communication AP 16, the division number (information indicating which part of the original packet was known), the packet size of the original packet, and the like necessary for the restoration of the packet are included in the communication AP header. (See FIG. 4).

  In step C3, even when there is a packet lost at the time of restoration, a redundant message for error correction is prepared so that restoration is possible, and the created divided packet and redundant message are requested to be transmitted to UDP (see FIG. 4). .

  If the processing request content of the received packet is a restoration request in step C1, the packet ID, division number, packet size of the original packet, and transmission source are acquired and managed in step C4. In Step C5, when the necessary number of divided packets managed are collected, the original packets are restored (Step C6) and transmitted to the IP 15 via the communication AP interface 13 and the communication AP transfer layer 14. If the necessary number of packets divided within a predetermined time period after the start of management is not obtained, expired packets (all packets with the same source and packet ID) are discarded.

  FIG. 9 is a diagram showing the communication protocol configuration of the router shown in FIG. 2 as functional blocks, and the same functional parts as those in FIG. 2 are denoted by the same reference numerals. 9, the transmission path interface unit 11 (12) is equivalent to the transmission path interface 11 (12) in FIG. 2, and the communication AP interface unit 13 is equivalent to the communication AP interface 13 in FIG.

  The communication AP transfer processing unit 14 is equivalent to the communication AP transfer layer 14 of FIG. 2, and performs packet division / restoration determination processing. The IP processing unit 15 is equivalent to the IP 15 in FIG. 2 and performs IP processing on the packet. The communication AP processing unit 16 is equivalent to the communication AP 16 in FIG. 2 and performs packet division / restoration processing. The UDP processing unit 17 is equivalent to the UDP 17 in FIG. 2, and performs UDP processing for a packet.

  It is obvious that each of these functional units is realized by reading a program recorded in advance on a recording medium such as a ROM in a CPU (central processing unit) of the computer and sequentially executing processes according to the procedure of the program. is there.

  As described above, according to the present invention, by generating and transmitting a redundant packet for error correction at the time of packet division, even if there is a loss in the divided packet at the time of restoration, communication is successful. The rate drop can be suppressed. In addition, since a packet division and restoration function common to each transmission path is provided independently of the router's IP unit (protocol layer functional part for IP processing), it is configured by various transmission paths using IPv6. Even if a dedicated network is constructed, the development scale can be reduced.

1 is a schematic system configuration diagram to which an embodiment of the present invention is applied. It is a communication protocol block diagram of a router in an embodiment of the present invention. It is a figure for demonstrating the flow of the packet division process of the router in embodiment of this invention. It is a figure which shows an example of the packet division | segmentation at the time of the packet division | segmentation process of the router in embodiment of this invention. It is a figure for demonstrating the flow of the packet restoration process of the router in embodiment of this invention. It is a processing flow figure of a communication AP transfer layer. It is a processing flow figure of a communication AP interface. It is a processing flow figure of communication AP. It is a functional block diagram of a router of an embodiment of the invention.

Explanation of symbols

1, 2 hosts
3, 4 routers
5-7 Transmission path 11, 12, 18 Transmission path interface (Transmission path interface)
13 Communication AP interface (Communication AP interface part)
14 Communication AP transfer layer (Communication AP transfer processing part)
15 IP (IP processing part)
16 Communication AP (Communication AP Processing Unit)
17 UDP (UDP processing part)
100 Split process flow
200 Flow of restoration processing

Claims (11)

A communication device that performs IP processing on a packet from one IP transmission path by IP means and transmits the packet to another IP transmission path,
Division determination means for determining whether or not to divide the packet from the IP means based on the maximum packet size that can be transmitted on the other transmission path;
And a dividing unit that divides the packet and generates a redundant packet of the divided packet and derives it to the IP unit when the division determining unit determines that the packet should be divided. Divided based on the maximum packet size that can be transmitted on the IP transmission path, and received from the transmission path together with the redundant packet of this divided packet, and IP processing is performed by the IP means on the divided packet and the redundant packet to obtain another packet. A communication device for transmitting to an IP transmission path,
Restoration determination means for judging whether or not to restore a fragmented packet from the IP means;
A communication apparatus, comprising: a packet restoring means for performing packet restoration based on the divided packet and the redundant packet and deriving the packet to the IP means when it is determined by the restoration judging means to restore. A communication device that performs IP processing on a packet from one IP transmission path by IP means and transmits the packet to another IP transmission path,
A division for determining whether or not the packet from the IP means should be divided based on the maximum transmittable packet size of the other transmission path, and for determining whether or not the divided packet from the IP means should be restored / Restoration determination means,
When it is determined by the division / restoration determination means that the packet should be divided, a packet is divided and a redundant packet of this divided packet is generated, and when it is determined by the division / restoration determination means that it should be restored And a packet fragmentation / restoration means for restoring the fragmented packet and deriving it to the IP means.   The communication device according to claim 1, wherein the communication device is a router.   A communication system using the communication device according to claim 1. An operation control method in a communication apparatus that performs IP processing on a packet from one IP transmission path by IP means and transmits the packet to another IP transmission path,
A division determination step for determining whether or not to divide the packet from the IP means based on the maximum transmittable packet size of the other transmission path;
And a dividing step of dividing the packet and generating a redundant packet of the divided packet and deriving it to the IP means when it is determined to be divided by the division determining step. Divided based on the maximum packet size that can be transmitted on the IP transmission path, and received from the transmission path together with the redundant packet of this divided packet, and IP processing is performed by the IP means on the divided packet and the redundant packet to obtain another packet. An operation control method in a communication device that transmits to an IP transmission path,
A restoration determination step for determining whether or not to restore a fragmented packet from the IP means;
A packet restoring step of performing packet restoration based on the divided packet and the redundant packet and deriving the packet to the IP means when it is judged by the restoration judging step that restoration is to be performed; An operation control method in a communication apparatus that performs IP processing on a packet from one IP transmission path by IP means and transmits the packet to another IP transmission path,
A division for determining whether or not the packet from the IP means should be divided based on the maximum transmittable packet size of the other transmission path, and for determining whether or not the divided packet from the IP means should be restored / Restoration judgment step,
When it is determined in the division / restoration determination step that the packet should be divided, the packet is divided and a redundant packet of the divided packet is generated, and when the division / restoration determination step determines that the packet should be restored And a packet segmentation / restoration step of restoring the fragmented packet and deriving it to the IP means. A program for causing a computer to execute an operation control method in a communication apparatus that performs IP processing on a packet from one IP transmission path and transmits the packet to another IP transmission path,
A division determination process for determining whether or not to divide the packet from the IP process based on the maximum packet size that can be transmitted on the other transmission path;
A program comprising: dividing a packet when it is determined to be divided by the division determination process, and generating a redundant packet of the divided packet and deriving the packet to the IP process. Another IP transmission path that is divided based on the maximum transmittable packet size of the IP transmission path and receives the packet from the transmission path together with the redundant packet of the divided packet and performs IP processing on the divided packet and the redundant packet. A program for causing a computer to execute an operation control method in a communication device that transmits to a computer,
A restoration determination process for determining whether or not to restore a fragmented packet from the IP process;
A program comprising: a packet restoration step of performing packet restoration based on the divided packet and the redundant packet and deriving to the IP processing when it is judged that the restoration judgment process should restore. A program for causing a computer to execute an operation control method in a communication apparatus that performs IP processing on a packet from one IP transmission path and transmits the packet to another IP transmission path,
A division for determining whether or not a packet from the IP processing should be divided based on a maximum transmittable packet size of the other transmission path and for determining whether or not a divided packet from the IP processing should be restored / Restoration judgment process,
When it is determined by the fragmentation / restoration determination process that the packet should be divided, the packet is divided and a redundant packet of this fragmented packet is generated, and when it is determined by the fragmentation / restoration determination step that it should be restored A packet division / restoration process for restoring the fragmented packet and deriving it to the IP process.

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