JP2006157544A - Packet communication equipment, packet communication system and packet communication control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of an IP fragment in an intermediate node (interface), etc., of a communication path at the time of transmitting packet data by a PPP (point to point protocol). <P>SOLUTION: In packet communication equipment, an MTU (maximum transmission unit) value is stored in an MRU (maximum receive unit) identifying device 20. A transmission and reception controller 10 discriminates the type of a packet received from a transmission source, and transmits the packet to the MRU identifying device 20 in the case of an LCP (link control protocol) configure-request packet. The MRU identifying device 20 extracts an MRU value from the LCP configure-request packet, compares the MRU value with a stored MTU value and determines an MTU value that does not cause an IP fragment. Concretely, the MRU value is reduced beforehand as much as an increase in data size by encapsulation or the like before data transfer of a PPP packet, and the changed MRU value is notified to other packet communication equipment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a packet communication apparatus, a packet communication system, and a packet communication control method that do not cause an IP fragment in an intermediate node (interface) or the like of a communication path when performing packet communication by PPP (Point to Point Protocol). .

  In a communication network, an MTU (Maximum Transmission Unit) is a value indicating the maximum value of data that can be transmitted in one transfer, and this MTU is determined in advance by the interface of the network device. For example, Ethernet (registered trademark) ) Is determined to be 1500 bytes.

  Recently, a method of encapsulating an IP packet in an IP packet using a method called encapsulation, such as VPN (Virtual Private Network), has come to be frequently used. Since this is a method of overlaying the IP header on the IP header, the packet size (length) may exceed the MTU value of the interface in the route due to the header being multiplexed during the encapsulation process. There is sex. In that case, the interface performs IP fragmentation and divides the packet for transmission. The IP fragmented packet is reassembled at the final destination, but if there is no fragmented packet on the way, data will not reach unless the packet is retransmitted from the transmission source. Therefore, it is necessary to avoid IP fragments as much as possible in PPP communication.

  FIG. 6 is a diagram illustrating an example of a protocol stack using PPP. In the case where communication is performed between the user's personal computer or the like EUD (End User Development) 1 and the network management apparatus (PDSN) 2 using the PPP protocol. In this example, the user terminal 3 and the base station 4 exist on the communication path between the EUD 1 and the network management device 2. In this case, when a packet of a predetermined size is transmitted from the EUD 1 to the network management device 2, the RP (A10 / A11) protocol is used for communication between the base station 4 and the network management device 2, so this part Thus, an IP header or the like is further added to the packet. When the packet size with the IP header added exceeds the MTU value of the base station 4, an IP fragment is generated in the base station 4.

  FIG. 7 shows an example of a PPP session connection sequence. The PPP connection sequence is performed through a PPPoE discovery stage, an LCP negotiation, and an IPCP negotiation procedure. In the first discovery stage of the PPPoE protocol, a PADI (PPPoE Active Discovery Initiation) packet is sent to the IP communication network when a terminal device (EUD or the like) is connected to the IP communication network (network management device or the like). The IP communication network receives the PADI packet and returns a PADO (PPPoE Active Discovery Offer) packet to the terminal device of the transmission source. The terminal device that has received the PADO packet sends back a PADR (PPPoE Active Discovery Request) packet and requests the start of a PPPoP session. On the other hand, a PPPoE session is established when the IP communication network sends back a PADS packet to which a session ID is added.

  Next, LCP negotiation is performed by PPP LCP (Link Control Protocol), a Configure-Request packet and a Configure-Ack (acknowledgement) packet are exchanged, a mutual communication condition such as a packet size is determined, and authentication is performed. That is, at this point, the MTU value is exchanged according to MRU (Maximum Receive Unit: the size of the data field in the maximum PPP message that can be received by executing PPP). Thereafter, IPCP negotiation is performed by the IPCP protocol (Internet Protocol Control Protocol), and after IP addresses are exchanged, IP communication is started.

  As a conventional technique, a method and a system for generating a data packet in a heterogeneous network are known (see, for example, Patent Document 1). This prior art is a method of fragmenting a packet, but it is not divided at the maximum MTU, but at a size that can be sent by the size of each packet, and is divided so as to have an equal length. Thereby “provides a technique to reduce the maximum fragmentation size and reduce the probability of fragmentation”.

However, in this prior art, it takes time to determine the minimum MTU in the interface existing in the path searched using Path MTU (Path MTU Discovery), and a load is imposed on a network device in the middle. Further, although there are network nodes that use ICMP packets but do not transmit ICMP packets depending on the policy, the problem is not always solved. Further, where IP fragmentation is required, the situation in which IP fragmentation is performed remains the same.
Japanese Patent Laid-Open No. 11-112574

  As described above, in the communication network, the MTU is determined by the interface of the network device. However, the size (length) of the packet exceeds the MTU value of the interface in the route due to encapsulation, addition of an IP header, or the like. There was a possibility. In this case, the interface performs IP fragmentation, divides and transmits the packet, and the IP fragmented packet is reassembled at the final destination. However, if there is no longer one packet divided along the route, data will not reach unless the packet is retransmitted from the transmission source, and it is necessary to avoid IP fragments as much as possible.

  The present invention has been made to solve such a problem, and the object thereof is to prevent IP fragments from being generated in intermediate nodes (interfaces) of a communication path when packet data is transmitted by PPP. A packet communication device, a packet communication system, and a packet communication control method are provided.

The present invention has been made in order to solve the above-mentioned problems, and the invention according to claim 1 is a packet communication apparatus for transmitting and receiving packet data, wherein a data transmission unit for transmitting packet data information, and the packet A transmittable data size storage unit that stores a transmittable data size that can be transmitted by the communication device, a receiving unit that receives packet data information, and a packet communication device that is another source included in the packet data A received data size information extracting unit for extracting and storing received data size information representing the received data size of the received data, an additional information adding unit for adding additional information to the data information to be transmitted, and the other stored transmission source A transmission information data size that is a data size of the received data size information of the packet communication device and the additional information; and A data size comparison unit that compares the data size with a credible data size, and the transmission unit includes means for canceling transmission of the data information to be transmitted based on a comparison result of the data size comparison unit. Packet communication device.
As a result, it is possible to avoid the occurrence of an IP fragment at an intermediate node (interface) in the communication path during PPP data transfer.

The invention according to claim 2 is the packet communication device according to claim 1, wherein the transmission unit has the transmission information data size larger than the transmittable data size as a result of comparison by the data size comparison unit. In such a case, there is provided means for stopping transmission of the transmission data information.
As a result, it is possible to avoid the occurrence of an IP fragment at an intermediate node (interface) in the communication path during PPP data transfer.

The invention according to claim 3 is the packet communication apparatus according to claim 1, wherein the transmission unit has the transmission information data size larger than the transmittable data size as a result of the comparison by the data size comparison unit. In such a case, the communication device includes means for notifying another communication device to reduce the received data size of the other packet communication device.
As a result, the data size to be transmitted in the packet can be reduced in advance by the increase in the data size due to encapsulation or the like, and there is no need to perform IP fragmentation after the packet arrives at an intermediate node (interface) or the like.

The invention according to claim 4 is a packet communication system in which packet communication devices communicate with each other via a relay device, wherein the packet communication device includes a data transmission unit that transmits packet data information; A transmittable data size storage unit that stores a transmittable data size that can be transmitted by the packet communication device, a receiving unit that receives packet data information, and reception of the relay device included in the packet data information A reception data size information extraction unit that extracts and stores reception data size information representing a data size, an additional information addition unit that adds additional information to the data information to be transmitted, and the stored reception data size of the relay device A transmission information data size that is a data size of information and the additional information, and the transmittable data size. A data size comparison unit for comparison, and when the relay device is switched to another relay device, the data size comparison unit switches the transmission information data size of the relay device after switching, and the transmittable data size, If the transmission information data size is different from that before the switching of the relay device, the relay device after the switching is notified to change the reception data size of the relay device.
Thus, in a packet communication system in which packet communication devices communicate with each other via a relay device, it is possible to avoid the occurrence of an IP fragment during PPP data transfer when the relay device is switched (handover).

The invention according to claim 5 is a packet communication control method in a packet communication apparatus that transmits and receives packet data, a procedure for transmitting packet data information, and a transmission that can be transmitted by the packet communication apparatus. A procedure for storing a possible data size, a procedure for receiving a packet, a procedure for extracting and storing received data size information indicating a received data size of another packet communication device included in the packet data, and , A procedure for adding additional information to the data information to be transmitted, and a transmission information data size that is a data size that is a combination of the received data size information of the stored other packet communication device of the transmission source and the additional information, The procedure of comparing the transmittable data size and the data to be transmitted based on the comparison result of the data size A packet communication control method characterized by including the steps to stop the transmission of the broadcast.
As a result, it is possible to avoid the occurrence of an IP fragment at an intermediate node (interface) in the communication path during PPP data transfer.

Further, the invention according to claim 6 is the packet communication control method according to claim 5, wherein the transmission information data size exceeds the transmittable data size according to the comparison result of the data size. It includes a procedure for stopping transmission of data information.
As a result, it is possible to avoid the occurrence of an IP fragment at an intermediate node (interface) in the communication path during PPP data transfer.

Further, in the invention according to claim 7, in the invention according to claim 5, when the transmission information data size exceeds the transmittable data size according to the data size comparison result, the other packet communication device. Including a procedure of notifying another packet communication apparatus so as to reduce the received data size.
As a result, the data size to be transmitted in the packet can be reduced in advance by the increase in the data size due to encapsulation or the like, and there is no need to perform IP fragmentation after the packet arrives at an intermediate node (interface) or the like.

The invention according to claim 8 is a packet communication control method in a packet communication system in which packet communication apparatuses communicate with each other via a relay apparatus, wherein the packet communication apparatus transmits packet data information. A procedure for storing a transmittable data size that can be transmitted by the packet communication device, a procedure for receiving packet data information, and a reception data size of the relay device included in the packet data information. A procedure for extracting and storing received data size information, a procedure for adding additional information to the data information to be transmitted, and a data size combining the stored received data size information of the relay device and the additional information A procedure for comparing the transmission information data size and the transmittable data size, and the relay device When switching to a device, the data size comparison unit compares the transmission information data size of the relay device after switching with the transmittable data size, and the transmission information data size is switched to the relay device. And a procedure for notifying the relay device after the switching to change the received data size of the relay device if it is different from the previous one.
Thus, in a packet communication system in which packet communication devices communicate with each other via a relay device, it is possible to avoid the occurrence of an IP fragment during PPP data transfer when the relay device is switched (handover).

  In the present invention, it is possible to avoid the occurrence of IP fragmentation in an intermediate node (interface) or the like of a communication path when packet data is transmitted by PPP.

Hereinafter, a packet communication device according to an embodiment of the present invention will be described with reference to the drawings.
<First Embodiment>
In the first embodiment of the present invention, an MTU value of a packet communication apparatus (node) is stored in a packet communication apparatus (for example, an intermediate node (interface) in the middle of a communication path). Then, an MRU value is extracted from a PPP (LCP Configure-Request) packet received from the transmission source, and the MRU value is compared with the stored MTU value to determine an MRU value at which no IP fragment occurs. Specifically, the MRU value is decreased by an amount that is increased in advance by encapsulation, addition of an IP header, or the like before data transfer of the PPP packet. Then, the changed MRU value is notified to other packet communication devices. This eliminates the need for IP fragmentation after the packet arrives at the node. As described above, since the MRU determination process is not performed by the PPP end device but the MRU value determination process is performed by an intermediate node or the like of the network, there is no need to change the application at the end. In addition, it is not necessary to send a plurality of packets of various lengths, and it is less burdensome on the network.

  FIG. 1 is a diagram illustrating a configuration example of a packet communication apparatus according to the present invention, and illustrates an example in which a packet communication apparatus according to the present invention is configured by a transmission / reception control apparatus 10 and an MRU identification apparatus 20. In FIG. 1, the transmission / reception control device 10 detects a PPP LCP Configure-Request packet and sends the LCP Configure-Request packet to the MRU identification device. The MRU identification device 20 extracts an MRU (Maximum-Receive-Unit) value from the LCP Configure-Request packet. Then, if (MRU value + amount increased by encapsulation)> (MTU of source interface), the MRU identification device 20 reduces the MRU value and rewrites. If (MRU value + amount increased by encapsulation) = <(MTU of source interface), the MRU value is left as it is. The inspected LCP Configure-Request packet is returned to the transmission / reception control device 10.

  FIG. 2 is a diagram illustrating an internal configuration example of the packet communication apparatus illustrated in FIG. 1. In FIG. 2, the data type detection unit 11 in the transmission / reception control device 10 performs a process of determining whether or not the received data is an LCP Configure-Request packet for LCP negotiation. The data transmission unit 12 transmits packet data to other packet communication devices and the like. The encapsulated header size storage unit 21 in the MRU identification device 20 performs a process of storing the size of the header used for encapsulation. The transmittable data size storage unit 22 performs processing for storing a transmittable data size (MTU) that can be transmitted by the packet communication apparatus.

  The reception data size information extraction unit 23 performs processing of extracting and storing reception data size information representing the reception data size of another transmission source packet communication device included in the received packet data. The additional information adding unit 24 performs processing for adding additional information such as IP header information to the data information to be transmitted. The data size comparison unit 25 compares the transmission information data size, which is the data size of the received data size information of the other packet communication device of the transmission source and the additional information such as the IP header, with the transmittable data size. I do. The MRU rewrite holding unit 26 performs a process of changing and holding the MRU value based on the comparison result of the data size comparison unit 25.

  FIG. 3 is an explanatory diagram of the operation of the MRU identification device 20. The MRU identification device 20 sets a length that is incremented from the header used for encapsulation, and stores it in the encapsulation header size storage unit 21 in the MRU identification device 20. Further, the MTU value for each interface is checked and recorded in the transmittable data size storage unit 22 (step S1).

  Next, the data type detection unit 11 in the transmission / reception control device 10 detects whether the received packet is an LCP Configure-Request packet. If it is an LCP Configure-Request packet, it is transmitted to the MRU identification device 20 (step S2). The reception data size information extraction unit 23 in the MRU identification device 20 extracts the MRU value from the LCP Configure-Request packet (step S3).

  Then, the additional information adding unit 24 in the MRU identification device 20 adds the extracted MRU value and the incrementing length. Then, the data size comparison unit 25 compares the MRU value to which the increment is added with the MTU value. If the added value is larger than the MTU value, an IP fragment occurs, so the MRU rewrite holding unit 26 extracts the MRU value and subtracts the incremented length (rewrites the MRU value). If it is smaller, the MRU value is left as it is (step S4). The rewritten MRU value is held (step S5). The MRU identification device 20 sends the LCP Configure-Request packet that has been checked to the transmission / reception control device 10 and transmits the LCP Configure-Request packet to the interface to be transferred by the data transmission unit 12 in the transmission / reception control device 10 ( Step S6).

  FIG. 4 is a diagram showing an example of a PPP connection sequence by the packet communication apparatus of the present invention. With reference to the PPP LCP negotiation portion of FIG. 4, a Configure-Request packet is first sent from the terminal device side to the intermediate node (interface) (step S11). The intermediate node extracts the MRU value in the Configure-Request packet and performs the MRU check (step S12). In this MRU value check, the extracted MRU value, the value obtained by adding the incrementing length, and the own MTU value are compared. If the added value is large, an IP fragment is caused. Therefore, the MRU value is taken out and the incremented length is subtracted (MRU value is rewritten). Then, a Configure-Request packet with the MRU value rewritten is transmitted to the IP communication network (step S13). Then, a Configure-Ack (approval) packet is transmitted from the IP communication network to the terminal device (step S14). Next, a Configure-Request packet is sent from the IP communication network to the intermediate node (step S15). The intermediate node extracts the MRU value from the received Configure-Request packet, and checks the MRU value (the validity of the MRU value is confirmed). Confirmation is performed (step S16), and this Configure-Request packet is transmitted to the terminal device (step S17).

  Through such a processing procedure, the terminal device and the IP communication network obtain an MRU value that does not cause an IP fragment in the intermediate node, and in subsequent IP communication, based on this MRU value, the data to be sent is divided. Send.

  As described above, in the first embodiment, before PPP data transfer, the data size to be transmitted in packets is reduced by an amount corresponding to the increase in data size by encapsulation or the like in advance. ) And the like, it becomes unnecessary to perform IP fragmentation after the packet arrives. This process can be performed at an intermediate node of the network, and in this case, there is no application change at the end. Further, unlike the case of using the conventional Path MTU, it is not necessary to send a plurality of packets having various lengths, and since it can be performed before the communication path is established, there is little burden on the network.

<Second Embodiment>
The first embodiment is an example of a case where the route between the terminal device and the IP communication network is fixed, and once the MRU value that does not cause an IP fragment is determined in the middle of the communication route, the terminal device is thereafter referred to. Is an example in which communication can be performed without generating an IP fragment if data to be transmitted is divided based on the MRU value (fixed value). However, the present invention is not limited to this, and the present invention is also effective when the terminal device is a mobile communication terminal or the like, and handover with the base station is performed while the mobile communication terminal or the PPP session continues.

  FIG. 5 is a diagram for explaining a second embodiment of the present invention. The example shown in FIG. 5 is an example in which the mobile communication terminal 31 moves and performs handover from the base station 5 to the base station 6 while continuing the PPP session with the network management device 2. In this example, the communication path with the network management apparatus 2 changes from the communication path a to the communication path b. In this case, an RP (A10 / A11 interface) session is established between the base station 6 and the network management device 2. In this state, an optimum MTU value is obtained by, for example, Path MTU (RFC 1191). Based on this MTU value, an MRU value that can be transmitted without causing an IP fragment is determined by the same procedure as described in the first embodiment, and based on this MRU value, the mobile communication terminal 31 divides and transmits data.

  Note that it is necessary to notify the mobile communication terminal 31 and the network management device 2 from the base station 6 to change the MTU, but since PPP does not have a standard for this, Lcp Configure-Option or the like is used. Do it yourself.

  As a result, even when the mobile communication terminal 31 is handed over, the base station is changed, and the communication path is changed, the optimum MRU value can be obtained and data can be transmitted.

  As described above, in the present invention, before the data transfer of PPP, by reducing the data size to be transmitted in packets by the amount of data size increased by encapsulation or the like in advance, the intermediate node (interface) or the like This eliminates the need for IP fragmentation after the packet arrives.

  The transmission / reception control device 10 and the MRU identification device 20 shown in FIGS. 1 and 2 have a computer system therein. A series of processes related to the above-described process is stored in a computer-readable recording medium in the form of a program, and the above-described process is performed by the computer reading and executing this program.

  That is, in each process in the transmission / reception control device 10 and the MRU identification device 20, a central processing unit such as a CPU reads the above program into a main storage device such as a ROM or RAM, and executes information processing and arithmetic processing. Is realized.

  Here, the computer-readable recording medium means a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Alternatively, the computer program may be distributed to the computer via a communication line, and the computer that has received the distribution may execute the program.

  Although the embodiment of the present invention has been described above, the packet communication apparatus of the present invention is not limited to the above illustrated example, and various modifications can be made without departing from the scope of the present invention. Of course.

  In the present invention, before PPP data transfer, the packet size arrives at an intermediate node (interface) or the like by reducing the data size to be transmitted in packets by an amount corresponding to the increase in data size by encapsulation or the like in advance. Therefore, the present invention is useful for packet communication apparatuses, packet communication control methods, and the like.

It is a figure which shows the structural example of the packet communication apparatus by this invention. It is a figure which shows the internal structural example of the packet communication apparatus shown in FIG. It is operation | movement explanatory drawing of a MRU identification device. It is a figure which shows the example of the PPP connection sequence by the communication apparatus of this invention. It is a figure for demonstrating the 2nd Embodiment of this invention. It is a figure which shows the example of the protocol stack using PPP. It is a figure which shows the example of the connection sequence of a PPP session.

Explanation of symbols

1 EUD (Personal Computer)
2 Network management device 3 User terminal 4, 5, 6 Base station 10 Transmission / reception control device 11 Data type detection unit 12 Data transmission unit 20 MRU identification device 21 Encapsulated header size storage unit 22 Transmittable data size storage unit 23 Received data size information Extraction unit 24 Additional information addition unit 25 Data size comparison unit 26 MRU rewrite holding unit 31 Mobile communication terminal

Claims (8)

In a packet communication device that transmits and receives packet data,
A data transmitter for transmitting packet data information;
A transmittable data size storage unit that stores a transmittable data size that can be transmitted by the packet communication device;
A receiving unit for receiving packet data information;
A reception data size information extraction unit that extracts and stores reception data size information indicating the reception data size of another transmission source packet communication device included in the packet data;
An additional information adding unit for adding additional information to the data information to be transmitted;
A data size comparing unit that compares the transmission information data size, which is a data size of the received data size information of the other packet communication device of the other transmission source and the additional information, and the transmittable data size; Prepared,
The packet communication device, wherein the transmission unit includes means for canceling transmission of the data information to be transmitted based on a comparison result of the data size comparison unit. The said transmission part is provided with a means to stop transmission of the said transmission data information, when the said transmission information data size exceeds the said transmittable data size as a result of the said data size comparison part comparing. Item 4. The packet communication device according to Item 1. If the transmission information data size exceeds the transmittable data size as a result of the comparison by the data size comparison unit, the transmission unit transmits the received data size of the other packet communication device to another communication device. The packet communication device according to claim 1, further comprising a notification unit. A packet communication system in which packet communication devices communicate with each other via a relay device,
The packet communication device is:
A data transmitter for transmitting packet data information;
A transmittable data size storage unit that stores a transmittable data size that can be transmitted by the packet communication device;
A receiving unit for receiving packet data information;
A received data size information extracting unit that extracts and stores received data size information representing the received data size of the relay device included in the data information of the packet;
An additional information adding unit for adding additional information to the data information to be transmitted;
A transmission information data size that is a data size combining the stored reception data size information of the relay device and the additional information, and a data size comparison unit that compares the transmittable data size;
When the relay device is switched to another relay device, the data size comparison unit compares the transmission information data size of the relay device after switching with the transmittable data size, and the transmission information data size The packet communication system is characterized by notifying the relay device after the switching to change the received data size of the relay device when is different from that before the switching of the relay device. A packet communication control method in a packet communication device that transmits and receives packet data,
A procedure for transmitting packet data information;
A procedure for storing a transmittable data size that can be transmitted by the packet communication device;
The procedure for receiving the packet;
A procedure for extracting and storing received data size information indicating the received data size of the other packet communication device included in the packet data;
A procedure for adding additional information to the data information to be transmitted;
A procedure for comparing a transmission information data size, which is a data size that is a combination of the received data size information of the stored other packet communication device of the transmission source and the additional information, and the transmittable data size;
A packet communication control method comprising: a step of canceling transmission of the data information to be transmitted based on a comparison result of the data size. The packet communication according to claim 5, further comprising: a step of stopping transmission of the transmission data information when the transmission information data size exceeds the transmittable data size based on the comparison result of the data size. Control method. A step of notifying another packet communication device to reduce the received data size of the other packet communication device when the transmission information data size exceeds the transmittable data size according to the data size comparison result; The packet communication control method according to claim 5. A packet communication control method in a packet communication system in which packet communication devices communicate with each other via a relay device,
The packet communication device is:
A procedure for transmitting packet data information;
A procedure for storing a transmittable data size that can be transmitted by the packet communication device;
A procedure for receiving packet data information;
A procedure for extracting and storing received data size information representing the received data size of the relay device included in the data information of the packet;
A procedure for adding additional information to the data information to be transmitted;
A procedure of comparing the transmission information data size, which is a data size of the stored reception data size information of the relay device and the additional information, and the transmittable data size;
When the relay device is switched to another relay device, the data size comparison unit compares the transmission information data size of the relay device after switching with the transmittable data size,
A packet communication control method comprising: notifying the relay device after switching to change the reception data size of the relay device when the transmission information data size is different from that before switching of the relay device. .

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