JP2017005516A - Communication device, control method for the same, and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique in which a device having a plurality of communication interfaces can appropriately select a communication interface.SOLUTION: A communication device: associates a communication interface with a network identifier which identifies a network to store them in a storage section; determines whether the association between the first communication interface with the network identifier which other communication device belongs is stored in the storage section, when receiving a packet from the other communication device through the first communication interface; associates the first communication interface with the identification information for identifying the other communication device to register them in the storage section, when it is determined that the association is not held in the storage section; and transmits the packet to the other communication device through the first communication interface, on the basis of the registered association.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a communication apparatus, a control method therefor, and a computer program that perform communication using a predetermined protocol via a network.

  A configuration in which a communication device having a plurality of communication interfaces selects a communication interface to be used for communication is known. For example, Patent Document 1 describes a configuration in which when a device has a plurality of communication interfaces, the use frequency of the communication interface is managed and a communication interface with a low use frequency is selected.

  Patent Document 2 describes a configuration in which, when a device has a plurality of communication interfaces, a communication interface is selected according to the attractive force associated with the communication interface. Here, the incentive is a parameter reflecting the amount of communication traffic in the transmission path, and takes a larger value as the traffic amount increases.

JP 7-202943 A JP 2010-206467 A

  However, in the above-described conventional configuration, when a communication device is connected to a plurality of networks to which the same network address is assigned, the communication device cannot appropriately select a network and perform communication.

  For example, consider a case where a communication device is connected to two networks, the network mask length of these networks is 24, and the network address is 192.168.1.0. In this case, when the communication device transmits a packet to 192.168.1.154, there are a plurality of routing entries corresponding to the destination, and which one is selected depends on the implementation. Therefore, when a communication device responds to a request packet transmitted from a terminal on one network, if a routing entry that does not have this terminal is selected, the packet cannot be returned to this device.

  Thus, in the conventional configuration, when a communication device is connected to a plurality of networks having the same network address, the communication device may not be able to respond to a request packet from one network. .

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a technique that enables an apparatus including a plurality of communication interfaces to appropriately select a communication interface.

  In order to achieve the above object, a communication apparatus according to the present invention comprises the following arrangement. That is, a communication device having a plurality of communication interfaces, a holding unit that associates a communication interface with a network identifier for identifying a network, and stores them in a storage unit, and another communication device via a first communication interface A determination unit that determines whether a correspondence between the first communication interface and the network identifier to which the other communication device belongs is held in the storage unit when the packet is received; and the association by the determination unit Is registered in the storage unit in association with the first communication interface and identification information for identifying the other communication device, and the registration unit On the basis of the association registered by the second communication device to the other communication device via the first communication interface. It has a transmission means for transmitting the dot and.

  Further, a communication device according to another aspect of the present invention is a communication device having a plurality of communication interfaces, a holding unit that holds the communication interface and a network identifier for identifying a network in association with each other, When a packet is received from a communication device via a first communication interface, a network identifier to which the other communication device belongs is associated with a second communication interface different from the first communication interface Registration means for registering the first communication interface and identification information for identifying the other communication device in association with each other in the storage unit, and the first registration based on the association registered by the registration means. Transmitting means for transmitting a packet to the other communication device via the communication interface.

  A communication apparatus according to another aspect of the present invention is a communication apparatus having a plurality of communication interfaces. When a packet is received via any of the plurality of communication interfaces, the communication interface that has received the packet is Storage means for storing, and transmission means for transmitting a response packet to the packet via the communication interface stored by the storage means.

  According to the present invention, it is possible to provide a technique that enables a device including a plurality of communication interfaces to appropriately select a communication interface.

Network topology diagram showing network configuration example of communication system The figure which shows an example of the routing table which a communication apparatus hold | maintains Network topology diagram showing network configuration example of communication system The figure which shows an example of the routing table which a communication apparatus hold | maintains Network topology diagram showing network configuration example of communication system The figure which shows an example of the routing table which a communication apparatus hold | maintains Block diagram showing a configuration example of a communication device The figure which shows an example of the routing table which a communication apparatus hold | maintains The flowchart which shows the process sequence of the process which a communication apparatus performs The figure which shows an example of the routing table which a communication apparatus hold | maintains Network topology diagram showing network configuration example of communication system The figure which shows an example of the routing table which a communication apparatus hold | maintains The flowchart which shows the process sequence of the process which a communication apparatus performs The flowchart which shows the process sequence of the process which a communication apparatus performs The figure which shows an example of the routing table which a communication apparatus hold | maintains Flow chart showing the processing procedure for disconnection

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

<< Embodiment 1 >>
(routing)
In Internet communication, an IP (Internet Protocol) protocol is generally used. In Internet communication, when a packet is transmitted, a routing table is used to determine a communication interface (network I / F) to be transmitted. The routing table is a table indicating a route of a packet transmitted from the device. It is used to search from which communication interface the packet to be sent is sent, whether it is sent directly to the other party, or via a router.

  The entry of the routing table includes information such as an IP address (destination IP address), a gateway IP address (gateway address), a network mask length (subnet mask), and a communication interface. When routing is performed, first, a network IP address is obtained using the destination IP address of the packet to be transmitted and the network mask length of the entry in the routing table. That is, a mask length bit is extracted from the most significant bit of the destination IP address, and a network IP address is obtained by concatenating 0 to the extracted bit. Then, the network IP address is compared with the network address of the IP address of the routing table entry. If there is a match, the IP address is determined as a routing transfer destination. If there are a plurality of matches, the IP address with the longest network mask length is determined as the transfer destination.

  There may be a default entry in the routing table entry. This is an entry determined as a transfer destination when it does not match any of the other entries in the routing table. In addition, when a metric indicating the routing priority is defined in the routing table, when there are a plurality of items that match the IP address of the entry in the routing table, the transfer destination is determined according to the priority.

  As an example, a case where the communication apparatus (device) 1001 in FIG. 1 transmits to the PC-A 1003 will be described. Assume that a routing table 108 as shown in FIG. 2 is set in the communication apparatus 1001. Since the IP address of the PC-A 1003 is 192.168.1.30 and the network mask length of the routing entry 2012 is 24 bits, the network address to which the mask is applied is 192.168.1.0. The network address of 192.168.1.0 matches the destination IP address of the routing entry 2012. The communication interface of the routing entry 2012 is the network A, and since the gateway IP address is not set, the communication interface to be transmitted is the network A. Therefore, it can be seen that the communication device 1001 transmits directly to the PC-A 1003 via the network A.

  Next, a case where the communication apparatus 1001 in FIG. 1 transmits to the PC-B 1002 will be described. Since the IP address of PC-B is 192.168.25.64 and the network mask length of the routing entry 2012 is 24 bits, the destination network address to which the mask is applied is 192.168.25.0. The network address of 192.168.25.0 does not match the destination IP address of the routing entry 2012. Since the routing table 108 has no other entries other than the default entry 2013, the default entry 2013 is adopted as the transfer destination.

  The communication interface of the routing entry 2013 is the network A, and the gateway IP address is set. Therefore, the packet to be transmitted is transmitted from the network A to the router 1004 and relayed by the router 1004.

(When there are multiple communication interfaces)
As shown in FIG. 3, the mobile terminal 1005 may temporarily communicate with the communication device 1001 via a direct network connection. In this case, the communication device 1001 is simultaneously connected to two networks of the network A and the network C through two communication interfaces. In such a case, a routing table as shown in FIG. Similarly, in this case, when transmitting to the PC-A 1003, the routing entry 2012 of FIG. 4 is selected from the IP address 192.168.1.30 of the PC-A 1003, and the network A is selected as the communication interface.

  When transmitting to the PC-B 1002 in FIG. 3, the routing entry 2013 in FIG. 4 is selected from the IP address 192.168.25.64 of the PC-B, and the network A is selected as the communication interface. When transmitting to the mobile terminal 1005, the routing entry 2017 of FIG. 4 is selected from the IP address 172.23.43.154 of the mobile terminal 1005, and the network C is selected as the communication interface.

  Assume that the communication device 1001 is connected to a plurality of communication interfaces as shown in FIG. In this case, if the same network address is assigned to the communication device 1001 in the network A and the network C, routing entries having the same destination address are set in the routing table 108 (2012 and 2014 in FIG. 6).

  For example, when a packet is transmitted to 192.168.1.154, the routing entry 2012 and the routing entry 2014 match among the routing entries in the routing table 108 of FIG. Since the network mask length is also the same as 24, it is implementation-dependent which one is selected. Therefore, when the communication apparatus 1001 responds to the request packet transmitted from the mobile terminal 1005, when the routing entry 2014 is selected, the response can be correctly transmitted to the mobile terminal 1005. However, when the routing entry 2012 is selected, a response packet addressed to the mobile terminal 1005 is transmitted from the network A. As described above, in the conventional configuration, the communication device 1001 connected to a plurality of networks may not be able to appropriately select a network to which a packet is to be transmitted.

  When the request data is received through the network, the communication device according to the present embodiment associates the transmission source address (identification information of the transmission source communication device) of the request data with the communication interface that has received the request data. Register with. As a result, when responding to the request data, the response data can be transmitted by selecting the communication interface that received the request data by referring to the routing table, and the response data reaches the source of the request data It becomes possible to make it.

(Network topology)
FIG. 5 is a network topology diagram showing a network configuration of a communication system according to an embodiment (Embodiment 1) of the present invention. In this embodiment, a case where the communication apparatus (device) 1001 communicates with the PC-A 1003, the PC-B 1002, or the mobile terminal 1005 will be described as an example.

  The communication device 1001 is a communication device provided with a plurality of communication interfaces. The communication device 1001 selects a communication interface according to the routing table and transmits a packet. In the present embodiment, the communication device 1001 is connected to the network A and the network C. The PC-A 1003 is a personal computer (PC) connected to the network A. A router 1004 relays packets between the network A and the network B as necessary. A PC-B 1002 is a PC connected to the network B. The mobile terminal 1005 can be temporarily connected to the communication device 1001.

  In the example of FIG. 5, the network A and the network B are configured by wired networks such as Ethernet (registered trademark). A network C is a network when the communication device 1001 and the mobile terminal 1005 are connected, and is realized by a wireless network such as a wireless LAN.

  As shown in FIG. 5, the communication apparatus 1001 is assigned an IP address 192.168.1.2 in the network A and an IP address 192.168.1.5 in the network C. The mobile terminal 1005 is assigned an IP address 192.168.1.154 in the network C. The PC-A 1003 is assigned an IP address 192.168.1.30 in the network A. The router 1004 is assigned an IP address 192.168.1.1 in the network A and an IP address 192.168.25.1 in the network B. The PC-B 1002 is assigned the IP address 192.168.25.64 in the network B.

  FIG. 1 is a network topology diagram when the mobile terminal 1005 is not connected. In FIG. 1, unlike FIG. 5, the mobile terminal 1005 and the network C do not exist.

(Configuration of communication device)
FIG. 7 is a block diagram illustrating a configuration example of the communication apparatus 1001 according to the present embodiment. The communication device 1001 is realized by an information processing device such as a personal computer (PC), a tablet terminal, or a smartphone, for example.

  Reference numeral 102 denotes a CPU (Central Processing Unit). The CPU 102 cooperates with other components based on a computer program such as an operating system (OS) or an application program, and controls the overall operation of the communication device 1001. Reference numeral 103 denotes a DRAM (writable memory), which functions as a work memory (storage unit).

  Reference numeral 104 denotes a wired LAN module, which functions as a communication unit that performs communication via a wired network such as Ethernet (registered trademark) 110. The wired LAN module 104 is connected to the Ethernet (registered trademark) 110 via an interface (referred to as interface A). A wireless LAN module 105 functions as a communication unit that performs wireless communication via a wireless network. The wireless LAN module 105 is connected to the antenna 111 via an interface (referred to as interface B).

  Reference numeral 106 denotes a search unit (routing table search unit) that searches (searches) a routing table 108 to be described later according to a predetermined condition. Reference numeral 107 denotes a setting unit (routing table setting unit) that sets a value for the routing table 108.

  Reference numeral 108 denotes a routing table, which has a plurality of routing entries indicating at least correspondence relationships between communication interfaces and network addresses (network identifiers) for identifying networks. The routing table 108 is disposed and held in the DRAM 103 in the example of FIG. A specific example of the routing table will be described later. In this block diagram, for ease of explanation, the search unit 106 and the setting unit 107 are written as independent blocks, but may be realized by a program executed by the CPU 102.

  Reference numeral 109 denotes a ROM (read only memory) that stores a program executed by the CPU 102. Reference numeral 111 denotes a wireless LAN antenna.

  In the present embodiment, as an example, a case in which the communication device 1001 can communicate by two communication methods of a wired LAN and a wireless LAN will be described, but the communication interface provided in the communication device 1001 is not limited to these. For example, a plurality of communication interfaces of either a wired LAN or a wireless LAN may be provided. The communication method is not limited to a wired LAN or a wireless LAN. For example, Bluetooth (registered trademark) or NFC (Near Field Communication) may be used as a wireless communication method. Moreover, it can also be comprised as an alternative of a hardware apparatus with the software which implement | achieves a function equivalent to the above each apparatus.

(Routing table)
FIG. 8 is a diagram illustrating an example of the routing table 108 used in the description of the present embodiment. In FIG. 8, 2012, 2013, and 2015 are routing entries of the routing table. In the routing entry 2012, a destination IP address 192.168.1.0, a mask length 24, an MTU (Maximum Transmission Unit) 1500, and a communication interface of the network A are set. In the routing entry 2013, default, gateway address 192.168.1.1, MTU 1500, and network A communication interface are set as destination IP addresses. In the routing entry 2015, the destination IP address 192.168.1.154, the mask length 32, the MTU 1500, and the communication interface of the network C are set.

  FIG. 2 is a diagram of a routing table when the mobile terminal 1005 is not connected. In the routing table 108 of FIG. 2, unlike FIG. 8, the routing entry 2015 corresponding to the network C does not exist.

(Communication device operation)
The operation of the communication apparatus 1001 will be described with reference to FIGS. 1, 2, 5, 7, 8, and 9. FIG. 9 is a flowchart showing an operation procedure of the communication apparatus 1001 according to the present embodiment. Each step in FIG. 9 is executed based on the control of the CPU 102 of the communication apparatus 1001.

  First, it is assumed that the communication apparatus 1001 is connected only to the network A as shown in FIG. The configuration of the routing table 108 in this state is as shown in FIG. Next, it is assumed that the mobile terminal 1005 is connected to the communication device 1001, IP addresses are assigned to the communication device 1001 and the mobile terminal 1005, and the network C is configured as shown in FIG. As a result, the communication apparatus 1001 is simultaneously connected to the network A and the network C. As shown in FIG. 5, it is assumed that the network A and the network C are configured with the same network address. In this state, the operation of the communication apparatus 1001 when the mobile terminal 1005 transmits a packet to the communication apparatus 1001 will be described with reference to the flowchart of FIG.

  Upon receiving the packet (S201), the communication device 1001 searches the routing table using the packet source address as a key (S202). That is, in S201 and S202, in response to receiving a packet via any of a plurality of communication interfaces, a routing entry related to the network to which the source address of the packet belongs is searched in the routing table. As a result of the search, it is determined whether a routing entry excluding the default entry has been found (S203). If found (YES in S203), the process proceeds to S204, and if not found (NO in S203), the process proceeds to S206. In the example of FIG. 5, since the source address is 192.168.1.154, the routing entry 2012 is found as an entry corresponding to this source address in the routing table 108 of FIG. This is because 192.168.1.0 obtained by extracting 24 bits of the mask length from the most significant bit of the transmission source address matches the destination IP address of the routing entry 2012.

  In S204, the communication interface that received the packet is compared with the communication interface of the routing table entry found in S203. If they are the same (YES in S205), the process proceeds to S207, and if different (NO in S205), the process proceeds to S206. In the above example, the communication interface of the routing entry 2012 in FIG. 2 is the network A, whereas the communication interface of the received packet is the network C, and both are different. Therefore, the process proceeds to S206.

  In S206, a routing entry corresponding to the source address of the received packet is registered in the routing table 108. In the above example, the routing entry 2015 is registered as shown in FIG. When a routing entry is registered in response to packet reception, the network mask length is registered as 32 bits so that the IP address itself of the device can be compared instead of the network address. As described above, when a routing entry related to the network to which the transmission source belongs is found in the routing table, but the network I / F does not match the network I / F that received the packet, a new routing entry is added. That is, a routing entry that associates the communication interface that received the packet with the source address is registered in the routing table. Thereby, referring to the routing table, it is possible to send a response packet to the packet from the communication interface that has received the packet.

  Next, after the routing entry 2015 is registered as shown in FIG. 8, the operation of the communication device 1001 receiving the packet of the mobile terminal 1005 will be described with reference to FIG.

  Upon receiving the packet of the mobile terminal 1005 in S201, the communication device 1001 searches the routing table using the packet source address as a key (S202). In this example, the routing entry 2015 shown in FIG. 8 is found (YES in S203).

  In step S204, the communication interface that has received the packet is compared with the communication interface of the routing entry 2015. In this example, since the communication interfaces are the same (YES in S205), the routing entry is not registered, and the process proceeds to S207 to continue the reception process.

  Next, selection of a communication interface when the communication apparatus 1001 transmits a packet to the mobile terminal 1005 after the routing entry 2015 is registered as shown in FIG. 8 will be described with reference to FIGS.

  As described above, the IP address of the mobile terminal 1005 is 192.168.1.154. The routing table 108 in FIG. 8 includes three routing entries 2012, 2013, and 2015. Since the network mask length of the routing entry 2012 is 24 bits, the network address of the network C to which the mobile terminal 1005 is connected in the routing entry 2012 is 192.168.1.0. The address 192.168.1.0 matches the upper 24 bits of the destination IP address of the routing entry 2012. Subsequently, when compared with the routing entry 2015, since the network mask length of this entry is 32 bits, the network address for the mobile terminal 1005 in the routing entry 2015 is 192.168.1.154. This network address matches the destination IP address of the routing entry 2015. Since the network mask length of the routing entry 2012 is 24 bits and the network mask length of the routing entry 2015 is 32 bits, the routing entry 2015 having a longer bit length and matching bits is selected. The communication interface of the routing entry 2015 is the network C, and the gateway IP address is not set. Therefore, it can be seen that the communication interface to be transmitted is the network C and is directly transmitted to the mobile terminal 1005.

  Next, selection of a communication interface when the communication apparatus 1001 transmits a packet to the PC-A 1003 after the routing entry 2015 is registered as illustrated in FIG. 8 will be described.

  The IP address of the PC-A 1003 is 192.168.1.30. In comparison with the routing entry 2012, since the network address of the network A to which the PC-A 1003 is connected is 192.168.1.0, the destination address of the routing entry 2012 matches with 192.168.1.0. . In comparison with the routing entry 2015, since the network address for the PC-A 1003 is 192.168.1.30, this does not match the destination address 192.168.1.154 of the routing entry 2015. Therefore, the routing entry 2012 is selected, and the network A is selected as the communication interface.

  As described above, when the communication device 1001 receives a packet, the communication device 1001 searches the routing table from the source IP address of the packet. When the corresponding routing entry exists, the communication interface of the routing entry is compared with the communication interface that has received the packet. As a result of comparison, if these communication interfaces are different, the source IP address of the received packet is registered as an entry in the routing table. In this way, in the communication device 1001, the transmission source IP address and the communication interface are associated with each other and registered in the routing table, so that a response packet can be transmitted from the communication interface that has received the packet.

  When a packet is received, the routing table is searched from the source IP address of the packet, and if no corresponding routing entry is found, an entry in the routing table addressed to the source IP address is registered. Thus, even when the routing entry corresponding to the source IP address of the packet is not registered in the routing table, the source IP address and the communication interface are associated and registered in the routing table. Therefore, it is possible to transmit from the communication interface that has received the packet transmitted by the transmission partner.

  Next, as shown in FIG. 3, an operation example when the network addresses of the network A, the network B, and the network C are all different will be described with reference to FIG. 2, FIG. 3, FIG. 9, and FIG. In this state, it is assumed that the routing table 108 of the communication device 1001 has no registered routing entry for the network C and the mobile terminal 1005 transmits a packet to the communication device 1001 as shown in FIG. When receiving the packet (S201 in FIG. 9), the communication device 1001 searches the routing table using the packet source address as a key (S202). Since no routing entry other than the default entry is found in the routing table 108 of FIG. 2 (NO in S203), the routing entry 2020 of FIG. 10 is registered (S206). That is, as a result of the search, when a routing entry related to the network to which the transmission source belongs is not found, a routing entry that associates the communication interface that received the packet with the transmission source address is registered in the routing table. As a result, the packet can be transmitted to the mobile terminal 1005 via the network C thereafter.

  Next, as shown in FIG. 11, when the network addresses of the network B and the network C are the same, the communication device 1001 selects a communication interface when transmitting a packet to the mobile terminal 1005 as shown in FIGS. It explains using. In the example of FIG. 11, the IP address of the mobile terminal 1005 is 192.168.25.154. In this example, the communication apparatus 1001 holds the routing table 108 shown in FIG. In this case, in comparison with the routing entry 2012, the network address 192.168.25.0 of the network C to which the mobile terminal 1005 is connected does not match the destination address 192.168.1.0 of this entry. In comparison with the routing entry 2016, the network address 192.168.25.154 for the mobile terminal 1005 matches the destination address 192.168.25.154 of this entry. Therefore, the routing entry 2016 is selected, and the network C is selected as the communication interface. Therefore, as shown in FIG. 11, even if the network addresses of the network B and the network C are the same, the packet can be transmitted to the mobile terminal 1005 via the network C.

  Next, as shown in FIG. 11, when the network addresses of the network B and the network C are the same, the selection of the communication interface when the communication device 1001 transmits a packet to the PC-B 1002 will be described with reference to FIGS. I will explain. In the example of FIG. 11, the IP address of the PC-B 1002 is 192.168.25.64. In comparison with the routing entry 2012, the network address 192.168.25.0 of the PC-B 1002 does not match the destination address 192.168.1.0 of this entry. Even in comparison with the routing entry 2016, the network address of the PC-B 1002 does not match the destination address 192.168.25.154 of this entry. Since there is no other matching routing entry, the default routing entry 2013 is selected, the packet to be transmitted is transmitted to the router 1004 connected to the network A, and the router 1004 relays the packet. Therefore, it is possible to reach the packet to the PC-B 1002.

  As described above, when receiving a packet, the communication device 1001 searches the routing table from the source IP address of the packet. When the corresponding routing entry exists, the communication interface of the routing entry is compared with the communication interface that has received the packet. If the communication interfaces are different as a result of the comparison, the communication apparatus 1001 registers an entry in the routing table addressed to the source IP address. Thus, even when the network beyond the router and the network address of the source IP address of the received packet are the same, the communication device 1001 can transmit a response packet from the communication interface that has received the packet. it can.

<< Embodiment 2 >>
In the present embodiment, a configuration will be described in which whether or not a response to a received packet is necessary is determined and a routing entry is registered only when a response is necessary, so that an unnecessary routing table is not updated. The operation of the communication apparatus 1001 according to the present embodiment will be described with reference to FIGS. 1, 2, 5, 8, and 13. FIG. FIG. 13 is a flowchart showing an operation procedure of the communication apparatus 1001 according to the present embodiment. Each step of FIG. 13 is executed based on the control of the CPU 102 of the communication apparatus 1001.

  First, it is assumed that the communication apparatus 1001 is connected only to the network A as shown in FIG. The configuration of the routing table 108 in this state is as shown in FIG. Next, it is assumed that the mobile terminal 1005 is connected, an IP address is assigned to the mobile terminal 1005, and the network C is configured as shown in FIG. As a result, the communication apparatus 1001 is simultaneously connected to the network A and the network C.

  As shown in FIG. 5, it is assumed that the network A and the network C are configured with the same network address (192.168.1.0). When the device 1001 receives the packet (S1601 in FIG. 13), it checks whether it is a request packet in S1602. The request packet here is a packet in which the transmission side of the request packet requests a response from the reception side. Examples of the request packet include a TCP SYN packet and an ICMP Echo packet that are TCP connection requests. When a TCP SYN packet is received, a TCP SYN ACK packet is returned as a response to notify that the connection is accepted. When an ICMP Echo packet is received, an ICMP Echo Reply packet is transmitted. In this way, in S1602, it is determined whether it is necessary to respond to the received packet. If a response is required, that is, if the received packet is a request packet (YES in S1602), the process proceeds to S1603. If it is not necessary, that is, if it is not a request packet (NO in S1602), the process proceeds to S1608, and the reception process is continued without registering or updating the routing table.

  The processes after S1603 are the same as those in FIG. That is, in S1603, the routing table is searched using the packet source address as a key. As a result of the search, it is determined whether or not a routing entry excluding the default entry has been found (S1604). If found (YES in S1604), the process proceeds to S1605, and if not found (NO in S1604), the process proceeds to S1607. In the above example, since the source address is 192.168.1.154, the routing entry 2012 is found as an entry corresponding to this source address in the routing table 108 of FIG.

  In S1605, the communication interface that received the packet is compared with the communication interface of the routing table entry (2012 in the above example) found by the search. If they are the same (YES in S1605), the process proceeds to S1608, and if they are different (NO in S1605), the process proceeds to S1607. In the above example, the communication interface is the network A in the routing entry 2012 of FIG. 2, and the communication interface of the received packet is the network C. Therefore, the two are different. Therefore, the process proceeds to S1607.

  In step S 1607, a routing entry that associates the packet source address with the communication interface is registered in the routing table 108. In the above example, the routing entry 2015 in FIG. 8 is registered.

  As described above, in this embodiment, it is determined whether or not it is necessary to respond to a packet received by the communication apparatus, and a routing entry is added to the routing table only when necessary. For this reason, a routing entry is not added to a received packet that does not need to be transmitted, and malfunctions and unnecessary processing can be prevented.

<< Embodiment 3 >>
In the present embodiment, a configuration will be described in which a routing entry registered in response to reception of a packet is deleted from the routing table in response to termination of connection with the packet transmission source. The operation of the communication apparatus 1001 according to the present embodiment will be described with reference to FIGS. FIG. 14 is a flowchart when a packet is received, FIG. 15 is an example of the routing table 108 in the present embodiment, and FIG. 16 is a flowchart when the connection is disconnected. Each step in FIG. 14 and FIG. 16 is executed based on the control of the CPU 102 of the communication apparatus 1001.

(Routing table)
FIG. 15 is a diagram showing an example of the routing table 108 in the present embodiment. In the present embodiment, items of a flag and a reference counter are added to the routing entry. The flag is used to determine whether the entry has been added by receiving a TCP SYN packet. The reference counter is a counter that is incremented when a TCP SYN packet is received and a routing entry is used.

(Operation when receiving packets)
When the packet is received in S701 of FIG. 14, the communication device 1001 searches the routing table 108 with the source IP address of the received packet (S702).

  If the routing entry is not found (NO in S703), the process proceeds to S706, and it is determined whether the received packet is a connection request (TCP SYN) packet. When the routing entry is found (YES in S703), the communication interface of the received packet is compared with the communication interface of the routing entry (S704). If they are different (NO in S705), the process proceeds to S706, and if they are the same (YES in S705), the process proceeds to S708.

  In step S706, it is determined whether the packet received in step S701 is a connection request (TCP SYN) packet. Thereby, when it is determined that the received packet is a connection request (TCP SYN) packet (YES in S706), the process proceeds to S707. In S707, the reference counter is set to 1, the flag is set to SYN, and the routing entry is registered. Then, the process proceeds to S712 and the reception process is continued.

  If it is determined in S706 that the received packet is not a connection request (TCP SYN) packet (NO in S706), the process proceeds to S711. In S711, the routing entry is registered without setting the reference counter and the flag. Then, the process proceeds to S712 and the reception process is continued.

  In S708, it is determined whether the packet received in S701 is a connection request packet (TCP SYN). If the packet is not a connection request packet (TCP SYN) (NO in S708), the process proceeds to S712 and the reception process is continued. If it is a connection request packet (TCP SYN) (YES in S708), it is determined whether there is a SYN mark in the flag of the routing entry (S709). If there is no SYN mark (NO in S709), the process proceeds to S712 and the reception process is continued. If there is a SYN mark (YES in S709), the routing entry reference counter is incremented (S710). Then, the process proceeds to S712 and the reception process is continued.

(Connection disconnection operation)
Next, the operation when TCP communication is finished, the TCP connection is disconnected, and the TCP connection information is deleted will be described with reference to FIG. When the connection is deleted (S901), the process proceeds to S902. TCP connection information includes a combination of a destination IP address, a source IP address, a destination port number, and a source port number. In step S902, the routing table 108 is searched using the destination IP address in the TCP connection information as a key. If not found (NO in S903), the process proceeds to S908, and the connection information deletion process is continued. If found (YES in S903), the process proceeds to S904.

  In S904, it is determined whether the flag of the discovered routing entry has a SYN mark. When the SYN mark does not exist (NO in S904), the process proceeds to S908, and the connection information deletion process is continued. If the SYN mark exists (YES in S904), the process proceeds to S905.

  In step S905, the routing entry reference counter is decremented. In step S906, it is determined whether the reference counter of the routing entry is 0. If it is not 0 (NO in S906), the process proceeds to S908, and the connection information deletion process is continued. If it is 0 (YES in S906), the process proceeds to S907. In S907, the routing entry whose reference counter is 0 is deleted (S907), and the process proceeds to S908 to continue the connection information deletion process.

  As described above, in this embodiment, when the connection information is deleted after the connection is disconnected, the routing entry added by the connection request packet is deleted. For this reason, unnecessary routing entries can be deleted to prevent malfunction, and only necessary routing entries can be held in the routing table.

  The deletion of the routing entry from the routing table is not limited to when the connection with the transmission source of the received packet is terminated. For example, the routing entry may be deleted from the routing table when a predetermined time has elapsed since the routing entry was registered in the routing table. Specifically, for example, in a protocol having no connection such as UDP or ICMP, a timer for deleting a routing entry may be provided, and the disconnection process may be performed in response to the timer measuring a certain time.

  In each of the above embodiments, when data is received via any one of the communication interfaces in a communication device having a plurality of communication interfaces, response data for the data is transmitted from the communication interface that received the data. Specifically, the routing table is searched from the source IP address of the received packet, and if the communication interface of the searched routing entry is different from the interface that received the packet, the source routing entry is registered. Accordingly, it is possible to appropriately select a communication interface using the routing table and transmit a packet from an appropriate communication interface corresponding to the destination IP address of the packet to be transmitted.

<< Other Embodiments >>
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

1001: Communication device 102: CPU 103: DRAM 104: Wired LAN module 105: Wireless LAN module 106: Search unit 107: Setting unit 108: Routing table 109: ROM 110: LAN 111: antenna

Claims (16)

A communication device having a plurality of communication interfaces,
Holding means for associating and holding the communication interface and a network identifier for identifying the network in the storage unit;
Whether or not a correspondence between the first communication interface and the network identifier to which the other communication device belongs is held in the storage unit when a packet is received from another communication device via the first communication interface. Determination means for determining;
When the determination unit determines that the association is not held in the storage unit, the first communication interface and identification information for identifying the other communication device are associated and registered in the storage unit. Registration means;
A transmission unit configured to transmit a packet to the other communication device via the first communication interface based on the association registered by the registration unit;
A communication apparatus comprising:   The communication apparatus according to claim 1, wherein the holding unit holds a routing table having a plurality of routing entries in which a communication interface and the network identifier are associated with each other in the storage unit. In the case where a packet is received from the other communication device, it further includes search means for searching the routing table,
The communication device according to claim 2, wherein the determination unit determines whether the association is held in the storage unit based on a search result by the search unit.   When it is determined that the association is held in the storage unit, the registration unit associates the first communication interface with identification information for identifying the other communication device and registers the association information in the storage unit The communication apparatus according to claim 1, wherein the processing is not performed. A communication device having a plurality of communication interfaces,
Holding means for associating and holding the communication interface and a network identifier for identifying the network in the storage unit;
When a packet is received from another communication device via the first communication interface, a network identifier to which the other communication device belongs is associated with a second communication interface different from the first communication interface. If there is, a registration unit that registers the first communication interface and identification information for identifying the other communication device in association with each other in the storage unit;
A transmission unit configured to transmit a packet to the other communication device via the first communication interface based on the association registered by the registration unit;
A communication apparatus comprising:   The communication apparatus according to claim 1, wherein the network identifier is a network address in an IP (Internet Protocol) layer.   2. The transmission unit according to claim 1, wherein the transmission unit transmits a response packet to the packet received from the other communication device based on the association registered by the registration unit via the first communication interface. 7. The communication device according to any one of 1 to 6. A determination unit that determines whether to transmit a response packet to the packet received from the other communication device;
The communication device according to claim 7, wherein the transmission unit transmits the response packet when the determination unit determines that the response packet is to be transmitted.   9. The communication according to claim 1, further comprising: a deletion unit that deletes the association registered by the registration unit from the storage unit when disconnected from the other communication device. 10. apparatus.   9. The apparatus according to claim 1, further comprising a deletion unit that deletes the association registered by the registration unit from the storage unit when a predetermined time has elapsed since the registration by the registration unit. The communication apparatus as described in.   9. The apparatus according to claim 1, further comprising: a deletion unit that deletes the association registered by the registration unit from the storage unit when there is no communication with the other communication device for a predetermined time. The communication device according to item. A communication device having a plurality of communication interfaces,
When a packet is received via any of the plurality of communication interfaces, storage means for storing the communication interface that has received the packet;
A transmission means for transmitting a response packet to the packet via the communication interface stored by the storage means;
A communication apparatus comprising: A method of controlling a communication device having a plurality of communication interfaces,
A holding step of associating and holding the communication interface and the network identifier for identifying the network in the storage unit;
Whether or not a correspondence between the first communication interface and the network identifier to which the other communication device belongs is held in the storage unit when a packet is received from another communication device via the first communication interface. A determination step for determining;
When it is determined that the association is not held in the storage unit, a registration step of registering the first communication interface and identification information for identifying the other communication device in association with each other in the storage unit;
A transmission step of transmitting a packet to the other communication device via the first communication interface based on the registered association;
A control method characterized by comprising: A method of controlling a communication device having a plurality of communication interfaces,
A holding step of associating and holding the communication interface and the network identifier for identifying the network in the storage unit;
When a packet is received from another communication device via the first communication interface, a network identifier to which the other communication device belongs is associated with a second communication interface different from the first communication interface. A registration step of registering the first communication interface and the identification information for identifying the other communication device in association with each other in the storage unit;
A transmission step of transmitting a packet to the other communication device via the first communication interface based on the registered association;
A control method characterized by comprising: A method of controlling a communication device having a plurality of communication interfaces,
A storage step of storing a communication interface that has received the packet in a storage unit when a packet is received via any of the plurality of communication interfaces;
A transmission step of transmitting a response packet to the packet via the communication interface stored by the storage unit;
A method for controlling a communication apparatus, comprising:   A computer program for causing a computer to function as each unit included in the communication device according to any one of claims 1 to 12.

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