WO2019142327A1

WO2019142327A1 - Relay device and relay method

Info

Publication number: WO2019142327A1
Application number: PCT/JP2018/001625
Authority: WO
Inventors: 松平　直樹
Original assignee: 富士通株式会社
Priority date: 2018-01-19
Filing date: 2018-01-19
Publication date: 2019-07-25

Abstract

The present invention relays a packet to a communication device disposed in a subnet without using a routing protocol. The relay device is for relaying communication between a first communication device installed in a first network and a second communication device installed in a second network and is provided with a storage part and a proxy part. The storage part stores proxy correspondence information indicating a correspondence between a first address for identifying the first communication device in a first protocol and a second address for identifying the relay device in a second protocol. Upon receiving from the second communication device a request packet including a first request for resolving an address for identifying the first communication device in the second protocol from the first address, the proxy part acquires the second address by searching the storage part using the first address. The proxy part generates a response packet including the second address acquired from the storage part and transmits the response packet to the second communication device.

Description

Relay apparatus and relay method

The present invention relates to a relay apparatus and relay method for relaying packets.

Conventionally, the following techniques are known to enable data transfer such as packets between two communication devices. The first is a technology for address resolution using Address Resolution Protocol (ARP), Neighbor Discovery Protocol (NDP) or the like. In this technique, a data transmission source device acquires a Media Access Control (MAC) address corresponding to the Internet protocol (IP) address of a destination communication device on the same link. The same link refers to a transmission path not via a relay device such as a router. The transmission source device transmits data to which the acquired MAC address is assigned. Thereby, data is transferred from the transmission source device to the destination device.

The second technique is routing performed by the relay device. Routing is a technique of determining a data transmission path in a communication network and transmitting data to a destination device according to the determined transmission path. In routing, each of a plurality of relay devices in a communication network share an address such as a network address of a downstream subnet with each other. Further, each of these relay devices stores a routing table corresponding to a list of transmission paths etc. in the case where the communication device in each subnet is the destination. The routing table also includes information on the network topology around the relay device.

In transmission for routing, when the IP address of the data destination includes the network address of a certain subnet, etc., this data is transferred to a relay apparatus having the corresponding subnet downstream. The relay apparatus that has received the data acquires the MAC address corresponding to the destination IP address by the address resolution technology such as ARP / NDP described above, and stores the acquired MAC address in the Ethernet header (Ethernet: registered trademark) Send to a subnet Thus, data is transferred to the destination device. Also, when a device in a subnet transmits data to a device that does not exist in the same link, this data is sent to the relay device with the MAC address corresponding to the IP address of the relay device such as a default router as the destination.

Although the routing table may include information on a manually set static transmission route, the information collected by the relay device using the routing protocol to search for the network topology may be used. There are many.

Japanese Patent Application Publication No. 2004-72802

The arrangement of devices in a communication network is complex and often extensive. In such a case, in order to build the routing table, the relay device may have to store information on a large number of transmission paths in a limited storage space.

Also, the routing tables generated and stored by each of the plurality of relay devices in the communication network do not necessarily match each other. Therefore, data to be transferred may circulate in the communication network without being transferred to the destination communication device, or may be discarded. Furthermore, when connecting between subnets, the relay device may not be able to use the routing protocol.

An object according to one aspect of the present invention is to enable relaying of packets to communication devices arranged in a subnet without using a routing protocol.

A relay apparatus relaying communication between a first communication apparatus implemented in a first network and a second communication apparatus implemented in a second network includes a storage unit and a proxy unit. The storage unit stores proxy correspondence information indicating correspondence between a first address identifying a first communication device in a first protocol and a second address identifying a relay device in a second protocol. The proxy, upon receiving from the second communication device a request packet including a first request for resolving an address identifying the first communication device in the second protocol from the first address, The storage unit is searched by the address to obtain the second address. The proxy unit generates a response packet including the second address acquired from the storage unit and transmits the response packet to the second communication device.

According to the above aspect, the packet can be relayed to the communication device disposed in the subnet without using the routing protocol.

It is a figure showing an example of the relay system concerning this embodiment. It is a figure which shows an example of the relay apparatus which concerns on this embodiment. It is a figure showing an example of agency correspondence information. It is a figure which shows an example of the sequence of the relay process which concerns on this embodiment. It is a figure which shows an example of the hardware constitutions of a relay apparatus. It is a figure which shows an example of the IPv6 address processed by the relay apparatus which concerns on this embodiment. It is a figure which shows the other example of the IPv6 address processed by the relay apparatus which concerns on this embodiment.

FIG. 1 shows an example of the configuration of a relay system 1 according to the present embodiment. The relay system 1 communicates between one or more communication devices 3 in the subnet 2, the communication devices 5 on the network 4 side outside the subnet 2, and the communication devices 5 on the network 4 side and the communication devices 3 in the subnet 2. And a relay device 6 for relaying. The communication device 5 is, for example, a relay device such as a router. The subnet 2 is an example of a first network, the network 4 is an example of a second network, the communication device 3 is an example of a first communication device, and the communication device 5 is an example of a second communication device. is there.

FIG. 2 illustrates functional blocks of the relay device 6 according to the present embodiment. The relay device 6 includes a plurality of link handling processing units 60. The plurality of link corresponding processing units 60 are connected to one another by, for example, a bus (or space switch) 61. Each link processing unit 60 includes a network interface card (NIC) 600, a determination unit 601, a storage unit 602, a proxy unit 603, a request unit 604, and the like. Each link processing unit 60 includes a response processing unit 605, a header deletion unit 606, a reception buffer 607, a header attachment unit 608, a transmission buffer 609, and the like. Each link processing unit 60 may include other circuit elements not shown in FIG. 2, and may appropriately store a routing table for executing routing.

The NIC 600 includes a circuit for enabling the relay device 6 to communicate with other communication devices, relay devices, and the like.

The determination unit 601 determines whether the packet received by the relay device 6 via the NIC 600 contains an address resolution request (a request in ARP or NDP). Hereinafter, a packet including an address resolution request may be described as a request packet. That is, the request packet corresponds to a packet including an ARP request in the IPv4 network, and corresponds to a packet including an NDP request in the IPv6 network. A packet including an ARP request is also described as an ARP request below, and a packet including an NDP request is also described below as an NDP request. Further, the request packet received by the relay device 6 may be described as a first request packet, and the address resolution request included in the first request packet may also be described as a first request.

The determination unit 601 can also determine whether the packet received by the relay device 6 via the NIC 600 includes a response to the address resolution request. In the following description, it is assumed that the relay device 6 is connected to the IPv4 network. Therefore, address resolution is performed by ARP.

The storage unit 602 stores an ARP table and a proxy ARP table. In the ARP table, IP addresses and MAC addresses of the communication devices 3 arranged in the subnet 2 are stored in association with each other. The ARP table is created, for example, by learning. Therefore, when the relay device 6 receives an ARP request for a certain communication device 3 from the communication device 5, the MAC address corresponding to the ARP table may not be stored. The ARP table is an example of correspondence information.

In the proxy ARP table, as shown in FIG. 3, an IP address and a proxy MAC address are stored in association with each other for each communication device 3 disposed in the subnet 2. The proxy MAC address is a MAC address for proxying the communication device 3 that the relay device 6 notifies the transmission source of the request packet. The proxy MAC address is the MAC address of the relay apparatus 6 in this embodiment. As an example, the proxy MAC address is the MAC address of the NIC 600. When a plurality of communication devices 3 are mounted in the subnet 2, one proxy MAC address (that is, the MAC address of the relay device 6) may be associated with a plurality of IP addresses. . Also, in the proxy ARP table, the subnet mask and the MAC address of the relay apparatus 6 may be stored for each IP address. Furthermore, the proxy ARP table may be created in advance by a network administrator or a user. Alternatively, the proxy ARP table may be created by learning.

The proxy ARP table is an example of proxy correspondence information, and the embodiment of the present invention is not limited to this configuration. For example, when the relay device 6 is connected to an IPv6 network, a proxy NDP table may be stored in the storage unit 602 as proxy correspondence information. In the proxy NDP table, an IPv6 address and a proxy MAC address are stored in association with each other for each communication device 3 disposed in the subnet 2.

The IP address is an example of a first address, the proxy MAC address is an example of a second address, and the MAC address is an example of a third address. Also, the IP protocol is an example of a first protocol, and the Ethernet protocol is an example of a second protocol.

When the relay device 6 receives an ARP request for the communication device 3 from the communication device 5, the proxy unit 603 creates an ARP response. At this time, the proxy unit 603 refers to the proxy ARP table stored in the storage unit 602, and acquires the MAC address corresponding to the IP address of the target of the ARP request. In this example, as shown in FIG. 3, the MAC address of the relay apparatus 6 is stored in the proxy ARP table. Therefore, the proxy unit 603 acquires the MAC address of the relay apparatus 6 in response to the received ARP request. Then, the proxy unit 603 sets the MAC address of the relay device 6 acquired from the proxy ARP table in the ARP response, and writes the MAC address in the transmission buffer 609. Therefore, a packet including this ARP response is sent via the NIC 600 to the source of the ARP request. Corresponding to the response to the request packet, the packet related to the notification of the MAC address will be described as a response packet below. The response packet corresponds to an ARP response in the IPv4 network, and corresponds to an NDP response in the IPv6 network.

In the ARP request from the communication device 5 to the communication device 3 received by the relay device 6, when the MAC address corresponding to the designated IP address is not stored in the ARP table, the proxy unit 603 sends an ARP request to the request unit 604. Instruct to generate a request. This ARP request is a request for resolving the MAC address corresponding to that IP address. The request unit 604 generates an ARP request and writes it to the transmission buffer 609. This ARP request is broadcast to each relay device 3 arranged in the subnet 2. The request packet transmitted from the relay apparatus 6 may be described as a second request packet, and the address resolution request included in the second request packet may also be described as a second request.

Each communication apparatus 3 that has received the ARP request compares the IP address contained in the ARP request with its own IP address. Then, the communication device 3 whose IP addresses coincide with each other returns an ARP response including the MAC address assigned to the interface of the communication device 3 to the relay device 6. By this procedure, the relay device 6 can obtain the MAC address of the destination device (ie, the communication device 3).

The response processing unit 605 processes the ARP response received from the communication device 3. Specifically, the response processing unit 605 extracts the MAC address of the communication device 3 from the received ARP response, and registers the MAC address in the ARP table. That is, address learning of the communication device 3 is performed.

The header deletion unit 606 deletes the L2 header from the packet received via the NIC 600. The data block from which the L2 header has been deleted is temporarily stored in the reception buffer 607. The bus (or space switch) 61 guides the data block stored in the reception buffer 607 to the header attachment unit 608 or another link handling unit 60.

The header assignment unit 608 assigns an L2 header to the data block transmitted by the relay device 6. Then, the data block to which the L2 block is assigned is written to the transmission buffer 609. The combination of the header assignment unit 608, the transmission buffer 609, and the NIC 600 is an example of the transmission unit.

FIG. 4 illustrates the sequence of processing in the relay system 1 according to the present embodiment. A case where the communication device 5 shown in FIG. 1 transmits a packet to the communication device 3 in the subnet 2 via the relay device 6 will be described with reference to FIG. The communication device 5 illustrated in FIG. 4 may be a communication device 3 other than the destination communication device 3 in the subnet 2.

The communication device 5 transmits a request packet to the communication device 3 via the network 4 in order to resolve the MAC address (step S100). Then, the relay device 6 receives this request packet.

The relay device 6 transmits the request packet by multicast or broadcast to one or more communication devices 3 in the subnet 2 when the IP address of the destination set in the received request packet is not registered in the correspondence information. (Step S101). In the following, it is assumed that the IP address of the destination set in the packet may be described as the destination IP address. The relay device 6 may transmit a request packet by multicast or broadcast to one or more communication devices 3 in the subnet 2 even when the IP address is dynamically assigned to the communication device 3 in the subnet 2 .

The communication device 3 whose own IP address matches the destination IP address in the subnet 2 transmits a response packet to the relay device 6 (step S102). The response packet includes the MAC address of the communication device 3 whose IP address matches.

When the relay device 6 receives the response packet from the communication device 3, the relay device 6 receives the IP address of the transmission source of the response packet (that is, the destination IP address of the request packet received in step S100) and the MAC address included in the response packet. Associate and record in correspondence information. When registering the IP address of the transmission source of the response packet in the correspondence information by address learning, the relay device 6 associates the IP address with the proxy MAC address and records the IP address in the proxy correspondence information. When the proxy correspondence information is created in advance by the network administrator or the user, the process of step S103 below may be performed prior to steps S101 and S102.

The relay device 6 executes a proxy response to the request packet received in S100. That is, the relay device 6 searches for proxy correspondence information with the destination IP address set in the received request packet, and acquires the corresponding proxy MAC address. This proxy MAC address is the MAC address of the relay apparatus 6 in this embodiment. Then, the relay device 6 generates a response packet including the proxy MAC address acquired from the proxy correspondence information, and transmits the response packet to the transmission source of the request packet in step S100 (step S103).

The communication device 5 transmits, to the relay device 6, a content packet that is a packet following the request packet and stores the MAC address notified in step S103 in the header and includes data corresponding to the transfer content (step S104). ).

The relay device 6 extracts the MAC address corresponding to the destination IP address included in the content packet in the correspondence information. The relay device 6 stores the extracted MAC address in the header of the content packet. The relay device 6 transmits the content packet to the communication device 3 (step S105).

When the destination IP address in the request packet received in step S100 is registered in the correspondence information, the relay device 6 may omit the processing in steps S101 and S102.

The process of step S103 may be performed prior to the processes of steps S101 and S102. In this case, the relay device 6 having received the request packet from the communication device 5 in step S100 refers to the proxy correspondence information, and transmits the response packet including the proxy MAC address associated with the destination IP address in the request packet in step S101. Prior to the processing, it is transmitted to the communication device 5. If the destination IP address in the request packet received in step S100 is not included in the correspondence information, the relay device 6 may temporarily record the destination IP packet in the proxy correspondence information and associate the destination IP packet with the proxy MAC address. The relay device 6 may transmit a response packet including the associated proxy MAC address to the communication device 5 in step S103, and may perform the process in step S101.

FIG. 5 is a diagram illustrating the hardware configuration of the relay device 6. Here, the relay device 6 has hardware as a general computer, and the processing by the relay device 6 is executed by specifically using the hardware 7 described below.

The hardware 7 includes a processor 70, a memory 71, a communication interface circuit 72, a storage device 73, and the like connected to one another by a bus 74.

The processor 70 is, for example, a single-core, dual-core, or multi-core processor. The memory 71 is, for example, a read only memory (ROM), a random access memory (RAM), a semiconductor memory, or the like, or a combination thereof. The reception buffer 607 and the transmission buffer 609 may be realized using the memory 71.

The processor 70 executes various programs (including a relay program) stored in the memory 71 to determine the determination unit 601, the proxy unit 603, the request unit 604, the response processing unit 605, the header deletion unit 606, and the header attachment unit. Each function of 608 is realized.

The communication interface circuit 72 is a circuit for the relay device 6 to exchange information between the

communication devices

3 and 5 via the Internet, an intranet, a dedicated line or the like. The communication interface circuit 72 corresponds to the NIC 600.

The storage device 73 is, for example, a hard disk drive, an optical disk device, or the like, or a combination thereof, and may include a portable storage medium or the like. The storage device 73 implements the function of the storage unit 602 described above.

In addition to the case described above, all or some of the functions of the functional blocks of the relay device 6 shown in FIG. 2 may be realized by dedicated hardware as appropriate.

According to the relay device 6 of the present embodiment, even when a routing protocol can not be used or when it is desired to avoid various problems due to routing, packets addressed to the communication device 3 in the subnet 2 can be relayed.

<Other Embodiment 1>
When the network 4 is an IPv6 network and the subnet 2 is an IPv4 network, the relay device 6 executes a process related to a proxy NDP (this process is also described as a proxy NDP). In proxy NDP, in IPv6, the relay device 6 resolves the address by notifying the communication device 4 in the network 4 of its own MAC address instead of the MAC address of the communication device 3 as the destination. Point to The relay device 6 has a function of translating an address (or a header) between IPv4 and IPv6.

In the case where the network 2 is an IPv6 network, when the communication device 5 requests the MAC address of the communication device 3, the communication device 5 transmits an NDP request. The NDP request includes an IPv6 address that identifies the communication device 3.

When the relay device 6 receives this NDP request, it executes proxy NDP. Here, in the storage unit 602 of the relay device 6, proxy correspondence information indicating the correspondence between the IPv6 address for identifying the communication device 3 and the MAC address of the relay device 6 is stored. The proxy unit 603 creates an NDP response including the MAC address of the relay apparatus 6 using this proxy correspondence information. The relay device 6 transmits the NDP response to the communication device 5 to notify the communication device 5 of the MAC address of the relay device 6 as a MAC address corresponding to the IP address of the communication device 3.

The IPv6 address is not particularly limited, but may be, for example, the format shown in FIG. In the example shown in FIG. 6, an IPv4 address is assigned to the lower 32 bits of the 128-bit IPv6 address. This IPv4 address identifies the communication device 3. The IPv6 address may include a prefix specifying the subnet 2 in which the communication device 3 of the destination exists.

The above-described determination unit 601 and response processing unit 605 may have a function of acquiring an IPv4 address from an IPv6 address, for example. The determination unit 601 or the response processing unit 605 that acquires an IPv4 address from an IPv6 address may also be described as an address acquisition unit.

When the IPv6 address has the format shown in FIG. 6, the proxy correspondence information may indicate the correspondence between the IPv4 address identifying the communication device 3 and the MAC address of the relay device 6. In this case, the relay device 6 extracts the IPv4 address of the communication device 3 from the IPv6 address in the NDP request, searches for proxy correspondence information with the IPv4 address, and acquires the MAC address. This MAC address identifies the relay device 6. Then, the relay device 6 creates an NDP response including the MAC address of the relay device 6 and transmits the NDP response to the communication device 5.

When the relay device 6 receives the above-mentioned NDP request from the communication device 5, the relay device 6 executes a procedure for resolving the MAC address of the communication device 3. Here, the communication device 3 is implemented in the subnet 2 that provides IPv4. Therefore, in order to resolve the MAC address of the communication device 3, the relay device 6 executes a process related to ARP. At this time, the relay device 6 extracts an IPv4 address from the IPv6 address shown in FIG. 6, generates an ARP request including the IPv4 address, and broadcasts or multicasts to the subnet 2. Also, the relay device 6 receives, as an ARP response, a response packet including the MAC address from the communication device 3 to which this IPv4 address is assigned. Then, the relay device 6 stores, in the storage unit 602, correspondence information indicating correspondence between the IPv4 address of the communication device 3 and the MAC address. That is, correspondence information representing correspondence between the IPv4 address of the communication apparatus 3 and the MAC address is generated by address learning. However, correspondence information indicating correspondence between the IPv4 address and the MAC address of the communication apparatus 3 may be generated in advance by a network administrator or a user and stored in the storage unit 602.

In connection with the above-mentioned embodiment, relay device 6 may be provided with the encapsulation / decapsulation function of IPv4 over IPv6. In this case, the relay device 6 executes proxy NDP for the IPv6 address assigned to the encapsulation / decapsulation endpoint.

According to the relay device 6 according to the present embodiment, it is possible to transmit and receive packets between communication devices in each of the IPv6 network and the IPv4 network.

<Other Embodiment 2>
In the case where the network 4 is an IPv6 network and an L2 frame is stored in the IPv6 packet transmitted from the communication device 5, the relay device 6 can execute proxy NDP. In this case, the relay device 6 is implemented at the L2 over IPv6 endpoint. That is, the relay device 6 has an L2 over IPv6 encapsulation / decapsulation function.

When the communication device 5 requests the MAC address of the communication device 3, the communication device 5 transmits an NDP request. The NDP request includes an IPv6 address that identifies the communication device 3.

The IPv6 address given to the IPv6 packet transmitted from the communication device 5 is not particularly limited, but may be, for example, the format shown in FIG. In the example shown in FIG. 7, the MAC address is assigned to the lower 48 bits of the 128-bit IPv6 address. This MAC address identifies the communication device 3. The IPv6 address may include a prefix specifying the subnet 2 in which the communication device 3 of the destination exists.

When the relay device 6 receives the above NDP request, it executes proxy NDP. Here, in the storage unit 602 of the relay device 6, proxy correspondence information representing correspondence between the IPv6 address for identifying the communication device 3 and the MAC address of the relay device 6 as illustrated in FIG. 3 is stored. . The proxy unit 603 creates an NDP response including the MAC address of the relay apparatus 6 using this proxy correspondence information. The relay device 6 transmits the NDP response to the communication device 5 to notify the communication device 5 of the MAC address of the relay device 6 as a MAC address corresponding to the IP address of the communication device 3.

When the subnet 2 is an IPv4 network and the IPv4 address of the communication device 3 changes dynamically, the communication device 5 may not have information on the IPv4 address. The communication device 5 can transfer a packet to the relay device 6 using the IPv6 address and the proxy MAC address for the relay device 6 that transfers the packet to the destination communication device 3. The relay device 6 that has received the packet from the communication device 5 may transfer the packet based on the MAC address, and obtain the IPv4 address from the communication device 3 of the destination that has received this packet. Also, the relay device 6 may store the correspondence between the IPv6 address or MAC address of the destination of the packet and the IPv4 address of the communication device 3 of the destination.

According to this embodiment, even if the communication device 5 does not have the information on the IPv4 address of the destination communication device 3, the relay device 6 can transfer the packet from the communication device 5 to the communication device 3.

The present invention is capable of various embodiments and modifications without departing from the broad spirit and scope of the present invention. In addition, the embodiment described above is for describing the present invention, and does not limit the scope of the present invention. Various modifications made within the scope of the claims and the meaning of the invention are considered to be within the scope of the present invention.

1 relay system 2 subnet 3 5, communication device 4 network 6 relay device 600 Network Interface Card (NIC)
601 determination unit 602 storage unit 603 proxy unit 604 request unit 605 response processing unit 608 header attachment unit 609 transmission buffer 70 processor 71 memory 72 communication interface circuit 73 storage device 74 bus

Claims

A relay apparatus relaying communication between a first communication apparatus implemented in a first network and a second communication apparatus implemented in a second network, the relay apparatus comprising:
A storage unit storing proxy correspondence information representing correspondence between a first address identifying the first communication device in a first protocol and a second address identifying the relay device in a second protocol;
When a first request packet comprising a first request to resolve an address identifying the first communication device in the second protocol from the first address is received from the second communication device, The storage unit is searched by the first address to acquire the second address, and a response packet including the second address acquired from the storage unit is generated and transmitted to the second communication device. A proxy,
A relay device provided with
The second request packet may include a second request packet including a second request to resolve an address identifying the first communication device in the second protocol from an address identifying the first communication device in the first protocol. The relay device according to claim 1, further comprising a request unit that transmits data to one communication device.
A response packet including a third address identifying the first communication device in the second protocol is received from the first communication device, and the correspondence between the first address and the third address is determined. The relay device according to claim 1, further comprising a response processing unit that writes correspondence information to be expressed in the storage unit.
In the storage unit, correspondence information representing correspondence between the first address and a third address for identifying the first communication device in the second protocol is stored in advance. The relay device according to Item 1.
The data packet is obtained by searching the correspondence information at the first address when a data packet to which destination information including the first address and the second address is added is received from the second communication device. The relay apparatus according to claim 3, further comprising: a transmission unit that transfers the data packet to the first communication apparatus using a third address.
The first protocol is IPv6,
The proxy unit executes NDP (Neighbor Discovery Protocol) instead of the first communication device on the first request packet received from the second communication device. The relay device according to any one of 5.
It further comprises an address acquisition unit for acquiring the IPv4 address of the first communication device from the IPv6 address of the destination of the first request packet received from the second communication device,
The relay apparatus according to claim 6, wherein the request unit broadcasts an ARP request for resolving a MAC address corresponding to the IPv4 address to the first network.
The relay apparatus according to claim 7, wherein the IPv6 address of the destination of the first request packet includes the IPv4 address of the first communication apparatus.
The relay device according to claim 6, wherein an IPv6 address of a destination of the first request packet includes the third address.
A relay method for relaying communication between a first communication device implemented in a first network and a second communication device implemented in a second network,
A request packet including a request to resolve an address identifying the first communication device in a second protocol from a first address identifying the first communication device in a first protocol, the second communication device Received from
A storage unit storing proxy correspondence information indicating correspondence between the first address and a second address identifying the relay device in the second protocol according to the request; Search and get the second address,
And generating a response packet including the second address acquired from the storage unit and transmitting the response packet to the second communication device.