JP6354431B2 - Storage device - Google Patents

Description

  The present invention relates to a storage device connected to a LAN and an IP address exchange method for the storage device.

  In a home or office, a storage device (NAS: Network Attached Storage: NAS) having a storage means such as a hard disk is used. The NAS is connected to a home or office LAN and stores data used by other electronic devices in the LAN.

  There is a need to use NAS from external devices such as smartphones and tablet PCs that have become popular in recent years. Such external devices are frequently used not only in homes and offices but also at destinations due to the nature of the devices. The external device at the destination is connected to a wide area network such as the Internet via a mobile phone line or the like. Therefore, when an external device accesses a NAS in a home or office at the destination, access is made via a wide area network. In order to enable such access, a router that connects a wide area network and a LAN performs IP address conversion using a technique called NAPT or static IP masquerade.

  Opportunities to access specific servers on the LAN side via a wide area network tend to increase. For example, in a video distribution service, there is a case where access is flooded to a server (content server) that holds popular content. In this case, in order to reduce the load on the server, a content server is constructed by a plurality of mirror servers, and access is distributed. As a technology related to this, Patent Document 1 discloses a connection distribution device that prevents uneven access to a specific mirror server among a plurality of mirror servers and distributes the load on each mirror server.

JP 2003-152729 A

  With the spread of external devices, the demand for NAS capable of consolidating various types of enormous amounts of data into a single device is increasing. On the other hand, in recent years, the data amount of one content has increased due to improvement in image quality. Therefore, although the storage capacity of the NAS is very large and is currently increasing, the storage capacity may be saturated due to a rapid increase in the amount of data. In that case, it is necessary to add a new NAS.

  When the external device on the wide area network side accesses the NAS on the LAN side, the above-described address conversion table is used. However, since the address conversion table is created for each NAS, it is necessary to individually specify these NAS from the wide area network side. That is, in order to access desired content stored in any of a plurality of NAS, it is necessary to specify and specify the NAS (specifically, the port number) storing the content.

  However, when the number of contents stored in a plurality of NASs increases, the number of combinations of contents and NAS for storing the contents becomes enormous, and NAS identification becomes complicated. In order to avoid this, it is conceivable to add a device for automatically specifying the NAS for storing the desired content to the LAN. In this case, however, the cost will increase and the environment setting will also be specialized. It becomes an obstacle to popularization.

  Therefore, an object of the present invention is to provide a storage device that can easily access a desired storage device from the wide area network side even when a plurality of storage devices are installed in one LAN.

A first aspect of the present invention is a storage device, which can communicate with another storage device connected to a network via a communication unit, a storage unit for storing content, and accessible via the network A content list creation unit that creates a content list in which various contents and their locations are associated with each other, and when there is a read request from the external device that accesses the content via the network, And (b) the specified location is the other storage device, and the communication unit can communicate with the external device, and is the only one used in the network. The external device can read the content of the other storage device from the other storage device. So that the, and summarized in that a control unit for exchanging the IP address the communication unit with the IP address of the communication unit owns the other storage device is held.

  According to the present invention, it is possible to provide a storage device that can easily access a desired storage device from the wide area network side even when a plurality of storage devices are installed in one LAN.

FIG. 1 is a conceptual diagram of the present invention. FIG. 2 is a configuration diagram of a communication system including a storage device according to an embodiment of the present invention. FIG. 3 is a block diagram showing a storage device according to an embodiment of the present invention. FIG. 4 is a sequence diagram of an IP address exchange method at the time of reading according to an embodiment of the present invention. FIG. 5 is a sequence diagram of an IP address exchange method at the time of writing according to an embodiment of the present invention.

  A storage device according to an embodiment of the present invention will be described with reference to the drawings.

  The storage device according to the present embodiment stores contents used or created by the user such as moving images, images, and documents. The storage device is configured to be connectable to a network such as a LAN. When there is a content read request from an external device (terminal device) such as a computer or a mobile phone via this network, the storage device outputs the content to the external device.

  Furthermore, even when a plurality of storage devices according to the present embodiment are connected to the network, each storage device performs the above-described operation. At this time, each storage device executes a process of assigning a unique IP address accessible to the external device to the storage device that stores the content. That is, when this IP address is assigned to a storage device other than the storage device that stores the content, the IP address of the storage device that stores the content and the only IP address that can access the external device of the other storage device The process of exchanging with is executed. By this processing, the external device can access any of the plurality of storage devices according to the content while using the unique IP address. That is, as shown in FIG. 1, the external device can see only the storage device storing the content through the only “window” open to the outside of the network. In other words, each storage device constructs one virtual storage device to which the above unique IP address is assigned.

  Even when content is written from any external device to any of the plurality of storage devices according to the present embodiment, each storage device performs the above IP address exchange. In this case, the type (file format, content similarity, etc.) of the new content to be written (hereinafter, new content) is compared with the content in the content list. When there is content of the same or similar type, a unique IP address accessible to the external device is assigned to the storage device storing the content, and the new content is stored in this storage device.

  Hereinafter, a storage device according to an embodiment of the present invention will be described. FIG. 2 is a diagram showing a communication system 100 including the storage devices 10A and 10B according to the present embodiment. FIG. 3 is a block diagram showing the storage devices 10A and 10B according to the present embodiment. As will be described later, the storage device according to the present embodiment is a so-called NAS (Network Attached Storage) that stores content and has a communication function via the LAN 12. Hereinafter, for convenience of explanation, this storage device is referred to as NAS.

  As illustrated in FIG. 2, the communication system 100 includes an external device 40 connected to the wide area communication network 30, a router 14 connected to the wide area communication network 30 and the LAN 12, and a plurality of NAS 10 </ b> A and 10 </ b> B connected to the LAN 12. The installed NAS is not limited to the two shown in FIG. In the present embodiment, it is assumed that an IP address that can communicate only with the external device 40 is assigned to only the NAS 10A out of the two NAS 10A and 10B. In other words, only the NAS 10A has an IP address that can communicate only with an external device. Hereinafter, for convenience of explanation, an IP address that can communicate only with the external device 40 is referred to as a public IP address.

  The wide area communication network 30 is a wireless or wired communication network provided by a telecommunications carrier or the like, for example, the Internet to which a known protocol such as TCP / IP is applied. The LAN 12 is a communication network different from the wide area communication network 30 constructed by wireless or wired in a home or office.

  The external device 40 is a terminal device that is connected to the wide area communication network 30 wirelessly or by wire and has a function of communicating with a web server (not shown) of the wide area communication network 30. The external device 40 has a function of performing processing such as content recording, reproduction, input, and output. Examples of the external device 40 include a computer, a mobile phone such as a smartphone, a digital camera, and a digital video camera. When the external device 40 is a mobile phone, it may be connected to the wide area communication network 30 via a mobile communication network (not shown). Based on an address exchange process described later, the external device 40 executes at least one of reading content from the NAS 10A or NAS 10B and writing content to the NAS 10A or NAS 10B. The content is digital data such as moving images, music, documents, still images, and the like, and is not limited to entertainment.

  The router 14 is connected to the wide area communication network 30 and the LAN 12, and enables communication between the NAS 10 </ b> A or NAS 10 </ b> B and the external device 40 via the wide area communication network 30. However, as described above, the public IP address is assigned to the NAS 10A, but is not assigned to the NAS 10B. Therefore, the NAS 10B cannot communicate with the external device 40 unless the address exchange process described later is performed. The router 14 may have a function of operating as a wireless LAN access point. In this case, the router 14 establishes a wireless connection with various electronic devices located within the cover area of the router 14.

  The network addresses of the wide area communication network 30 and the LAN 12 are different from each other. In other words, the NAS 10A, 10B connected to the LAN 12 is assigned an IP address used in the LAN 12, and the IP address of the NAS 10A cannot be designated from outside the NAS 10A (ie, the wide area communication network 30). The same applies to the NAS 10B. Therefore, in order for the external device 40 to access the NAS 10A via the wide area communication network 30, the IP address used when designating the router 14 from the wide area communication network 30 is the IP assigned to the NAS 10A on the LAN 12 side. Processing to convert to an address is required. The router 14 previously holds a combination of these IP addresses as an address conversion table, and performs the IP address conversion based on the address conversion table when the communication is performed. This combination may include a port number held (set) by the NAS 10A.

  Although the IP addresses assigned to the NASs 10A and 10B are different, the configurations of the NASs 10A and 10B are the same. Therefore, the NAS 10A will be described, and the description of the NAS 10B will be omitted. As illustrated in FIG. 3, the NAS 10 </ b> A includes a communication unit 16, a storage unit 18, a content creation unit 20, and a control unit 22. The NAS 10A also includes an operation unit (not shown) such as a power switch and a reset button, and a display unit (not shown) that shows the operation status.

  The communication unit 16 is, for example, a wireless or wired LAN module. The communication unit 16 has an IP address assigned to the NAS 10 </ b> A, and communicates with the external device 40 through the LAN 12, the router 14, and the wide area communication network 30 using this IP address. The communication unit 16 also performs communication with the communication unit of the NAS 10B through the LAN 12. The communication unit 16 may include a USB module. In this case, content can be written to the storage unit 18 via the USB module.

  The storage unit 18 is an SSD (Solid State Drive) configured by a hard disk or a flash memory, and stores the above-described content. Further, the storage unit 18 stores the identification information of the NAS 10A. The identification information is, for example, an ID assigned to the NAS 10A or a MAC address possessed by the NAS 10A.

  The content creation unit 20 creates a content list in which all contents accessible by the external device 40 and their locations (for example, the MAC address of the NAS 10A) are associated with each other in the NAS connected to the router 14. When any of the NASs 10A and 10B stores new content, the content list is updated to include the content. The content list is stored in the storage unit 18, for example.

  The content list is referred to when the IP addresses of the NAS 10A and NAS 10B are exchanged. That is, when the external device 40 requests reading of the content stored in one of the NASs 10A and 10B, the NAS 10A that stores the content is specified based on the content list.

  The control unit 22 includes a central processing unit (CPU), a storage element such as a RAM and a ROM, and executes a series of processes in the NAS 10A based on a program stored in the storage element or the storage unit 18. As one of the series of processes, the control unit 22 exchanges the IP address of the NAS 10A and the IP address of the NAS 10B. Specifically, when there is a read request from the external device 40 for content stored in any of the NASs 10A and 10B, the location of the content is specified based on the content list, and the specified content is stored in the NAS 10B. If the NAS 10A has a public IP address (that is, an IP address that can only communicate with the external device 40), the NAS 10A is assigned to the communication unit 16 of the NAS 10A so that the external device 40 can read the content. The IP address assigned to the communication unit (not shown) of the NAS 10B is exchanged.

  In this embodiment, it is assumed that a public IP address is assigned to the NAS 10A. Therefore, the exchange of the IP address of each NAS is performed only when the content that has received the read request is stored in the NAS 10B. When the content that received the read request is stored in the NAS 10A, the control unit 22 does not exchange the IP address. That is, access from the external device 40 to the NAS 10A is maintained, and the external device 40 reads out desired content from the NAS 10A.

  Thus, in this embodiment, a public IP address is assigned to either NAS 10A or NAS 10B. On the other hand, the external device 40 reads the content of the NAS 10A or NAS 10B using the public IP address. Alternatively, the external device 40 writes the same or similar content as the content of the NAS 10A or NAS 10B to the NAS 10A or NAS 10B using the public IP address. Accordingly, since the external device 40 uses only one IP address, the state of accessing one storage device is maintained.

A content reading process according to the present embodiment will be described.
Each IP address of the NAS 10A, 10B is assigned by the router 14. The same applies when the router 14 functions as a DHCP server. Alternatively, a DHCP server may be separately prepared and the above allocation may be performed. Hereinafter, a case where the router 14 has a function as a DHCP server will be described.

  First, the NAS 10 </ b> A and 10 </ b> B is started in a state where it is connected to the router 14. The NASs 10 </ b> A and 10 </ b> B search for other NAS connected to the router 14. Through this search, NAS 10A finds NAS 10B, and NAS 10B finds NAS 10A. Thereafter, each NAS 10A, 10B creates a content list for all NAS (in this case, NAS 10A and NAS 10B) and stores this. That is, each NAS 10A, 10B shares the same content list. The content list is updated as needed, for example, when content is written. By sharing the content list, the content requested by the external device 40 can be searched only within the NAS operating as the parent NAS. That is, it is possible to reduce the search time and the processing load of other NAS.

  In the above state, it is not yet known which of the NASs 10A and 10B is assigned a public IP address. Therefore, each of the NASs 10A and 10B transmits a packet in which the transmission destination is itself and the public IP address is set as the transmission source to the wide area communication network 30. The NAS that has received this packet is a NAS (parent NAS) that can only communicate with the external device 40. In the present embodiment, for convenience of explanation, it is assumed that the NAS 10A starts operating as a parent NAS and the NAS 10B that has not received a packet starts operating as a child NAS capable of communication only within the LAN 12.

Next, a process until the content is transmitted to the external device 40 when the content is requested from the external device 40 will be described.
First, the external device 40 transmits a content read request to the router 14 (step S1). In response to this, the router 14 converts the IP address and then transmits a content read request to the NAS 10A as the parent NAS (step S2). The NAS 10A refers to the already created content list and searches for the location of the content (step S3).

  It is assumed that the NAS 10B, which is a child NAS, stores the content by this search (step S4). In this case, it is necessary to exchange the IP address of the NAS 10A and the IP address of the NAS 10B. Therefore, the NAS 10A instructs the NAS 10B to transmit an instruction for the router 14 to perform IP address reservation allocation (step S5). Based on the instruction in step S5, the NAS 10B requests reservation allocation of the IP address of the NAS 10A (step S6). In response to this, the router 14 performs reservation allocation of the MAC address of the NAS 10B and the IP address of the NAS 10A (step S7). If it is determined in step S3 that the content is stored in the NAS 10A, the NAS 10A immediately transmits the content to the external device 40, and the series of processing ends.

  After step S7, the NAS 10B notifies the NAS 10A that reservation allocation has been performed (step S8). Upon receiving this notification, the NAS 10A releases its own IP address (public IP address) (step S9), and notifies the NAS 10B of this release (step S10).

  Through the above processing, the public IP address is released from the NAS 10A and reserved in the NAS 10B. Next, the NAS 10B transmits a request for IP address reacquisition to the router 14 (step S11). In response to this, the router 14 prepares the assignment of the IP address of the NAS 10A to the NAS 10B (step S12). Thereafter, the NAS 10B transmits a “DHCP REQUEST” message to the router 14 (step S13), the router 14 transmits a “DHCP OFFER” message to the NAS 10B (step S14), and the NAS 10B transmits a “DHCP ACK” message to the router 14. (Step S15). By transmitting and receiving these messages, the NAS 10B acquires a public IP address, transmits the content requested by the external device 40 to the external device 40 (step S16), and a series of processing is completed.

  When the router 14 does not have a function as a DHCP server, the IP addresses of the NASs 10A and 10B are fixed. In this case, when the NAS 10A has a public IP address and the NAS 10B stores the content requested by the external device 40, the NAS 10A and 10B exchange IP addresses by direct communication between the two. This direct communication can be executed by using both identification information such as a MAC address. Thereafter, the NAS 10B transmits the content requested by the external device 40 to the external device 40.

  Next, content writing processing in the present embodiment will be described. Most of this processing is similar to the content reading processing described above. Therefore, only processes that are different between the two will be described, and the same processes are denoted by the same reference numerals and description thereof is omitted.

  In the content writing, the external device 40 transmits a content writing request to the router 14 (step S1 ′). In response to this, the router 14 converts the IP address, and then transmits a content write request to the NAS 10A as the parent NAS (step S2 ′). The NAS 10A refers to the already created content list and searches for the location of other content similar to the content to be written by the external device 40 (step S3 ′). This identity or similarity is determined by the control unit 22 based on the name, type, content, attribute, and the like of the content.

  It is assumed that the NAS 10B as a child NAS stores the same or similar content by this search (step S4 ′). The subsequent processing is the same as the content reading processing described above up to step S15. That is, the NAS 10B finally obtains the public IP address, and the external device 40 then writes the content in the NAS 10B (step S16 ′).

  According to the present embodiment, only one storage device (NAS) can be accessed from an external device. Therefore, there is only one combination of IP addresses (or combination of a set of port numbers corresponding to the IP addresses) necessary for address translation. This combination is not changed when a storage device is added. Therefore, it is not necessary for the external device to individually specify the storage device that stores the content. In addition, since each storage device performs the above address exchange, it is not necessary to separately prepare a dedicated device for performing this address exchange, and it is not necessary to provide such a function to an external device or a router.

  In addition, a user of an external device can process a plurality of storage devices as one storage device. Therefore, the user can be released from the troublesomeness of managing a plurality of storage devices. That is, it is possible to improve user convenience for reading and writing of content.

  Even when there are only one combination of IP addresses necessary for address conversion, it is possible in principle to output content to an external device without exchanging IP addresses. In this case, the storage device accessible from the external device receives the content from the storage device that stores the content and transmits the content to the external device. However, since it is necessary to transfer content between storage devices, there is an increased possibility that the transfer rate will decrease. In the case of the present embodiment, since the external device directly receives the content from the storage device that stores the content, the transfer rate does not decrease due to the transfer described above.

  Further, since the same or similar types of content are stored when new content is written, these contents are not scattered to a plurality of storage devices, and management is facilitated.

  In the above-described embodiment, the assignment of the public IP address to any of the plurality of NASs in the initial state is unconfirmed, and the assignment of the public IP address is confirmed using packet transmission and reception. However, in the router 14 functioning as a DHCP server, the public IP address may be excluded in advance from the automatic assignment list, and the public IP address may be assigned in advance to any of a plurality of NAS. In this case, the NAS to which the public IP address is assigned starts the operation as the parent NAS without using packet transmission and reception. When the content requested by the external device 40 or content related to this content is stored in the child NAS (NAS 10B), the parent NAS (NAS 10A) releases the public IP address and automatically assigns the IP address. Request to the router 14. On the other hand, the child NAS registers in the router 14 that the released public IP address is associated with its own MAC address. The router 14 updates the address conversion table based on this registration. Thereafter, as in the above embodiment, the child NAS is changed to a new parent NAS, and content is read from or written to the external device 40.

  DESCRIPTION OF SYMBOLS 10A, 10B ... Storage device (NAS), 12 ... LAN, 14 ... Router, 16 ... Communication unit, 18 ... Storage unit, 20 ... Content list creation unit, 22 ... Control unit, 30 ... Wide area communication network, 40 ... External device

Claims (1)

A storage device,
A communication unit capable of communicating with another storage device connected to a network via the network;
A storage unit for storing content;
A content list creation unit for creating a content list in which contents accessible via the network are associated with their locations;
When there is a read request from an external device that accesses the content via the network,
(a) identifying the location of the content based on the content list;
(b) is identified the location a said another storage device, and, if the communication unit is the external device capable of communicating with owns a unique IP address that is utilized by the network, the IP address of the external device is the so read out the contents of said another storage device from said another storage device, the communication unit with the IP address of the communication unit owns the other storage devices owns And a control unit for exchanging with each other.

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