JP6403566B2 - Transfer device, client device, and program for content distribution network - Google Patents

Description

  The present disclosure relates to a transfer device, a client device, and a program in a content distribution network that performs routing based on a name related to content.

  A network that distributes content based on a name indicating the content has been proposed. Patent Document 1 and Non-Patent Document 1 disclose a content-centric network (CCN) which is one of such networks.

JP 2009-277234 A

V. Jacobson, et al. , "Networking Named Content", in Proceedings of ACM CoNEXT 2009, December 2009

  In a content-centric network, a server device that publishes content divides the content into one or more objects called chunks, and a client device acquires content in units of the divided objects. In the content-centric network, a communication device that has transferred an object (hereinafter referred to as a transfer device) can store the object. When the transfer device receives an interest packet (request message) requesting an object held by the own device from the client device, the transfer device holds the interest packet without transferring it to the server device. The object can be transmitted to the client device that has transmitted the interest packet.

  Below, an example of operation | movement of a transfer apparatus is demonstrated. The transfer apparatus manages CS (Contents Store), FIB (Forward Information Base), and PIT (PIT: Pending Interest Table). The CS is information indicating an object held by the own device. The FIB is information indicating a relationship between an interest packet and an interface to which the interest packet is to be transferred. The PIT is information indicating the relationship between the object requested by the transferred interest packet and the interface that has received the transferred interest packet.

  When receiving the interest packet, the transfer device searches the CS and determines whether or not the object requested by the interest packet is held. If it is held, the object held by the own device is transmitted to the client device that is the transmission source of the interest packet. On the other hand, if the received interest packet does not hold the requested object, the PIT is searched, the interest packet requesting the same object as the interest packet is already transferred, and the object waiting to be received is received. It is determined whether it is in a state. In the state of waiting for reception, the received interest packet is not transferred, and the PIT is updated so that the reception interface of the interest packet is associated with the object requested by the interest packet. On the other hand, if the received interest packet is not waiting for the requested object, the interest packet is transferred from the interface determined based on the FIB and the PIT is updated. Further, when receiving the object, the transfer apparatus determines the transfer destination interface of the object based on the PIT, and deletes the information related to the object from the PIT. The transfer device updates the CS when the received and transferred object is saved.

  For example, in CCN, the maximum size of an object is 64 KB. Therefore, in the CCN, the client device needs to transmit a large number of interest packets in order to acquire the entire content. Further, when the transfer device receives the interest packet, it searches for each CS. Further, if the transfer device finds that the object requested by the interest packet is not held as a result of searching for the CS, the transfer device searches for the PIT. It is necessary to search one by one. Therefore, the network bandwidth is compressed by a large number of interest packets transmitted by the client device, and the processing load on the transfer device increases.

  The present invention suppresses the number of request messages transmitted by a client device and the processing load on a transfer device in a content distribution network that divides content into a plurality of objects for distribution.

According to one aspect of the present invention, a client device of a content distribution network that divides and distributes content into one or more objects is common to each of a plurality of object names indicating a plurality of requested objects and the plurality of object names . And generating means for generating a request message including information indicating the prefix and transmitting means for transmitting the generated request message to the content distribution network.

  According to one aspect of the present invention, a transfer device of a content distribution network that divides and distributes content into one or more objects stores the object name and the object indicated by the object name or is waiting for reception Holding means for holding one or more sub-tables including information indicating the object, a main table indicating the relationship between the prefix of the object name and the sub-table corresponding to the prefix, and a plurality of object names When the request message including the information indicating is received, the main table is searched with a prefix common to the plurality of object names, the sub table to be searched is determined, and the determined sub table to be searched is determined. Search for each of the plurality of objects indicated by the plurality of object names. And a processing means for performing processing for determining whether the object is a stored object, an object waiting for reception, and an object that is not stored and is not waiting for reception. And

  In a content distribution network that divides content into a plurality of objects for distribution, the number of request messages transmitted by the client device can be reduced, and the processing load on the transfer device can be reduced.

The block diagram of the content delivery network by one Embodiment. The figure which shows the interest packet which a client apparatus transmits in one Embodiment. The figure which shows the table which a transfer apparatus hold | maintains in one Embodiment. The figure which shows the interest packet which the transfer apparatus transmits in one Embodiment. The block diagram of the client apparatus by one Embodiment. The block diagram of the transfer apparatus by one Embodiment.

  Hereinafter, exemplary embodiments of the present invention will be described with reference to the drawings. In the following drawings, components that are not necessary for describing the embodiment are omitted from the drawings. Moreover, the following embodiment is an illustration and does not limit this invention to the content of embodiment.

  FIG. 1 is a configuration diagram of a content distribution system according to the present embodiment. A content distribution network composed of a plurality of transfer devices 2 is connected to a server device 3 that publishes content and a client device 1 that acquires content. Here, when acquiring content, the client device 1 transmits a request message (hereinafter, interest packet). The object name to be acquired is included in the interest packet. For example, when the content name “/ a / b / c / d / name1” is divided into ten, the object names of these ten objects are, for example, “/ a / b / c / d / name 1/1 "to" / a / b / c / d / name 1/10 ". Also, if a version exists in the content, the version name is included and "/ a / b / c / d / name1 / 1 / v1" to "/ a / b / c / d / name1 / 10 / v1" "(Indicating version 1)" and "/ a / b / c / d / name1 / 1 / v2" to "/ a / b / c / d / name1 / 10 / v2" (indicating version 2) are also objects Name. Of course, "/ a / b / c / d / name1 / 1 / v1" and "/ a / b / c / d / name1 / 1 / v2" indicate different objects.

  Conventionally, the client apparatus 1 transmits only one object name in one interest packet. Accordingly, when acquiring all of the content divided into 10 objects, the client device 1 transmits 10 interest packets, and the transfer device 2 of the content distribution network transmits 10 interest packets. Each had to be processed separately.

  In the present embodiment, the client apparatus 1 can include a plurality of object names having a common prefix in the object name in one interest packet. For example, in order to acquire all of the content names “/ a / b / c / d / name1” divided into 10 objects, the client device 1 can obtain “/ a / b / c / d / name1 / An interest packet including 10 object names from 1 "to" / a / b / c / d / name 1/10 "can be transmitted. Note that the client device 1 may transmit not only the object names of objects belonging to the same content but also an interest packet including object names of different contents (including differences in versions) having a common prefix in the object name. it can. In the following, as a general example, the client device 1 is “/ a / b / c / d / e / f / name1 / 1”, “/ a / b / c / d / e / f / name1 / 2”. "," / A / b / c / d / e / f / name2 / 1 "," / a / b / c / d / e / name1 / 1 "," / a / b / c / d / g / A case where five objects of name 1/1 ”are acquired will be described as an example.

  FIG. 2 shows an interest packet transmitted by the client device 1 when the above five objects are acquired. The interest packet in the present embodiment includes a common name field, a longest common name field, and an object name field. As shown in FIG. 2, the longest common name field is set with the longest name of the prefix common to the object names of the objects to be acquired (in this example, five). The object name field lists the names of objects to be acquired. Note that since the longest common name field is set with the longest name of a prefix having a common object name, only the remaining portion (postfix) may be set in the object name field. Note that the client device 1 does not set a value in the common name field. The role of the common name field will be described later.

  Next, processing performed by the transfer apparatus 2 that has received the interest packet illustrated in FIG. 2 will be described. As shown in FIG. 3, the transfer device 2 holds a main table and a plurality of sub tables linked from the main table. The main table is information indicating the relationship between the prefix of the object name and the sub table. The sub table is information indicating the object name including the prefix indicated by the main table and whether the object indicated by the object name is stored in the CS or included in the PIT. Note that objects not included in the sub-table are not stored in the CS and are not included in the PIT.

  The transfer apparatus 2 first determines whether the name included in the longest common name field of the received interest packet exists in the prefix of the main table. If it exists, it is determined whether each object name included in the object name field exists in the sub-table indicated by the prefix. In this example, “/ a / b / c / d” included in the longest common name field does not exist in the main table. In this case, the transfer apparatus 2 searches the main table using a common prefix other than “/ a / b / c / d” included in the longest common name field. For example, the transfer apparatus 2 determines whether the name deleted in order from the end of the longest common prefix exists in the main table. In this example, since “/ a / b / c” exists in the main table, the transfer apparatus 2 searches the sub table # 2 corresponding to “/ a / b / c” in the main table.

  As shown in FIG. 3, “/ a / b / c / d / e / f / name1 / 1” and “/ a / b / c / d / e / f / name1 / 2” included in the object name field. "Is stored in the CS is indicated in the sub-table # 2. Therefore, the transfer apparatus 2 has objects with names “/ a / b / c / d / e / f / name1 / 1” and “/ a / b / c / d / e / f / name1 / 2”. Is read from the CS and transmitted to the client device 1. Further, as shown in FIG. 3, sub-table # 2 indicates that “/ a / b / c / d / e / f / name2 / 1” included in the object name field is included in the PIT. Has been. Therefore, the transfer apparatus 2 adds the interface that has received the interest packet to the corresponding entry of the PIT. Further, the sub table # 2 of FIG. 3 includes “/ a / b / c / d / e / name1 / 1”, “/ a / b / c / d / g / name1 /” included in the object name field. 1 "does not exist. Therefore, the transfer device 2 transfers an interest packet including the two object names in the object name field. The interface that outputs the interest packet is determined based on the FIB.

  FIG. 4 shows an interest packet transferred by the transfer apparatus 2 in this example. In the object name field, two object names that are not included in the CS or the PIT are set. The longest common name field is the same as the received interest packet. Note that when the longest common name is changed to a longer name due to deletion of some object names from the object name field, the longest common name field may be updated. In the common name field, a prefix that matches the main table in the transfer apparatus 2, which is “/ a / b / c” in this example, is set. When the transfer device 2 transfers the interest packet, the transfer device 2 adds an entry related to the object included in the object name field of the transferred interest packet to the PIT and a corresponding sub table (sub table # in this example). Update 2).

  The transfer apparatus 2 that has received the interest packet of FIG. 4 transmitted by the transfer apparatus 2 in the previous stage first determines whether the prefix set in the common name field exists in the main table. This is because there is a high possibility that the same prefix as the prefix matched in the transfer device 2 in the preceding stage exists in the main table. If the prefix set in the common name field does not exist in the main table, the transfer apparatus 2 determines whether the prefix set in the longest common name field exists in the main table. If the prefix set in the longest common name field does not exist in the main table, the main table is searched with a common prefix other than the prefix included in the common name field and the longest common name field. .

  In this example, since there is an object that is not included in the CS or PIT in the object name field of the received interest packet, the interest packet is transferred. On the other hand, if there is no object that is not included in the CS or the PIT, the transfer apparatus 2 can discard the interest packet without transferring the interest packet. When receiving the object as a response to the transferred interest packet, the transfer apparatus 2 transfers the object based on the PIT and deletes the corresponding entry in the PIT. Also, the corresponding sub table is updated. Further, the received object can be held by the own device, and when held, the CS and the corresponding sub table are updated.

  As described above, the client device 1 according to the present embodiment includes a plurality of object names having a common prefix in the interest packet and requests a plurality of objects with one interest packet. As a result, the number of interest packets transmitted by the client device 1 can be reduced, and the content distribution network can be prevented from being compressed due to the transmission of a large number of interest packets to the content distribution network. The transfer device 2 has a two-layer structure of a main table and a sub table, and narrows down the sub table to be searched by using the main table. Therefore, the processing load on the transfer device 2 can be suppressed. Furthermore, by including the longest common prefix in the interest packet and the common prefix that matches the entry in the main table of the transfer apparatus 2, the main table search process in the transfer apparatus 2 at the subsequent stage can be performed quickly. it can.

  FIG. 5 is a configuration diagram of the client device 1 according to the present embodiment. When the user of the client device 1 inputs a content name acquired via the input / output unit 11, the interest packet generation unit 12 generates an object name and sets a plurality of object names having a common prefix in the object name field The interest packet included in is generated. In the interest packet, the longest prefix name common to a plurality of object names included in the object name field can be set. The transmission / reception unit 13 transmits the interest packet generated by the interest packet generation unit 12 to the content distribution network and receives an object from the content distribution network.

  FIG. 6 is a configuration diagram of the transfer device 2 according to the present embodiment. The interface unit 23 has a plurality of interfaces. The holding unit 21 holds the CS, PIT, and FIB, and the main table and sub table described with reference to FIG. When the processing unit 22 receives the interest packet via the interface unit 23, the processing unit 22 performs the above-described processing to transmit the held object and transfer the interest packet. When an object is received as a response to the transferred interest packet, the above-described processing is performed and the received object is transferred. The processing unit 22 manages and updates the CS, PIT, and sub-table. In the present embodiment, the received object is transferred based on the PIT. However, the information indicating the interface to which the transferred object is to be transmitted is not managed by the transfer device 2, but the transfer device 2 manages the PIT when it can be determined directly from the packet including the received object, for example. There is no need. In the PIT, only the object name included in the transferred interest packet is managed. However, the interest packet itself can also be included in the PIT entry.

  The common prefix included in the interest packet and the object name may be text data indicating them or a hash value of the text data. Furthermore, in this embodiment, the common name field and the longest common name field are provided in the interest packet. However, only one of them may be provided, or both may be provided. If there is a value in the common name field or the longest common name field, the transfer device 2 preferentially uses these values in the main table search. Further, the client device 1 and the transfer device 2 according to the present invention can be realized by programs that cause a computer to operate as the client device 1 and the transfer device 2, respectively. These computer programs can be stored in a computer-readable storage medium or distributed via a network.

Claims (12)

A client device of a content distribution network that divides content into one or more objects and distributes the content,
A plurality of object names respectively indicating the plurality of objects that require a generation means for generating a request message including information indicating a common prefix to the plurality of object names,
Transmitting means for transmitting the generated request message to the content distribution network;
A client device comprising:   The client device according to claim 1, wherein the generation unit includes information indicating a longest prefix among prefixes common to the plurality of object names in the request message. A transfer device of a content distribution network that distributes content into one or more objects and distributes the content,
One or more sub-tables including an object name, information indicating whether the object indicated by the object name is stored or waiting for reception, a prefix of the object name, and a sub-table corresponding to the prefix A main table indicating the relationship between
When a request message including information indicating a plurality of object names is received, the main table is searched with a prefix common to the plurality of object names, a sub table to be searched is determined, and the determined search target For each of the plurality of objects indicated by the plurality of object names by searching the sub table, any one of an object that is stored, an object that is waiting to be received, and an object that is not stored and is not waiting to receive Processing means for performing processing to determine whether or not
A transfer device comprising: The request message includes information indicating a first prefix that is the longest prefix among the common prefixes of the plurality of object names,
The processing means determines whether or not the first prefix exists in the main table, and if not, the prefix other than the first prefix among the common prefixes of the plurality of object names. The transfer apparatus according to claim 3, wherein the main table is searched by: The request message includes information indicating a second prefix that is a prefix used for determining the sub table in the main table of the transfer device in the preceding stage,
The processing means determines whether or not the second prefix exists in the main table, and if not, the prefix other than the second prefix among the common prefixes of the plurality of object names. The transfer apparatus according to claim 3, wherein the main table is searched by: The request message is used to determine the sub table in the main table of the transfer apparatus in the preceding stage, and information indicating the first prefix that is the longest prefix among the common prefixes of the plurality of object names. Information indicating a second prefix that is a prefix, and
The processing means determines whether the second prefix exists in the main table, and if not, determines whether the first prefix exists in the main table, and if not, 4. The transfer apparatus according to claim 3, wherein the main table is searched by a prefix other than the first prefix and the second prefix among the prefixes common to the plurality of object names. .   When there is an object that is not stored and is not waiting for reception in the plurality of objects indicated by the plurality of object names, the processing means sends a request message including information indicating the object name of the object to the content The transfer apparatus according to claim 3, wherein the transfer apparatus transmits to a distribution network.   The processing means includes an interest packet including information indicating an object name of the object because there is an object that is not stored and is not waiting to be received in the plurality of objects indicated by the plurality of object names. 8. The transfer apparatus according to claim 7, wherein when transmitting to the content distribution network, a prefix used for determining a sub table in the main table is included in the request message to be transmitted.   The processing means, when there is an object stored in a plurality of objects indicated by the plurality of object names, transmits the stored object to a transmission source of the request message. Item 9. The transfer device according to any one of Items 3 to 8.   When there is an object waiting for reception among the plurality of objects indicated by the plurality of object names, the processing means receives the request message in a wait table indicating an interface used for transferring the object waiting for reception. The transfer apparatus according to claim 3, wherein the transfer apparatus is added.   A program for causing a computer to function as the client device according to claim 1.   A program that causes a computer to function as the transfer device according to claim 3.

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