JP7164556B2 - TRANSFER DEVICE AND PROGRAM FOR CONTENT DISTRIBUTION SYSTEM - Google Patents

Description

The present disclosure relates to a transfer device and a program for a content distribution system that performs routing based on content names.

A content distribution system has been proposed that requests and distributes content based on a content name that indicates the content. Non-Patent Document 1 discloses one such system, Content Centric Networking (CCN).

In CCN, a server device that publishes content divides the content into one or more chunks, and the client device acquires the content in chunk units. Also, in CCN, a communication device that has transferred a chunk (hereinafter referred to as a transfer device) can store (cache) the chunk. When a transfer device receives an interest packet (request packet) requesting a cached chunk from a client device, the transfer device receives the cached chunk without forwarding the interest packet to the server device. • Can be sent to the client device that is the source of the packet.

An example of the operation of the transfer device will be described below. The transfer device manages CS (Contents Store), FIB (Forward Information Base), and PIT (PIT: Pending Interest Table). CS is information indicating cached chunks. The FIB is information indicating the relationship between the chunk requested by the interest packet and the interface that transmits the interest packet for the transfer of the interest packet. The PIT is information indicating the relationship between the chunk requested by the forwarded Interest packet and the interface that received the forwarded Interest packet.

Upon receiving an interest packet, the transfer device searches the CS and determines whether or not the chunk requested by the interest packet (hereinafter referred to as request chunk) is cached. If the request chunk is cached, a data packet including the cached request chunk is sent to the client device that sent the interest packet. Note that the interface that transmits the data packet is the interface that received the interest packet. On the other hand, if the request chunk is not cached, the forwarding device searches the PIT to determine if it has already forwarded another interest packet requesting the request chunk and is waiting to receive the request chunk. When in the reception wait state, the forwarding device does not forward the received Interest packet, but adds the receiving interface of the Interest packet to the entry of the request chunk in the PIT. On the other hand, if it is not waiting to receive a request chunk, the transfer device transmits (transfers) the interest packet from the interface determined based on the FIB, and adds an entry for the request chunk to the PIT. This entry has information indicating the request chunk and information indicating the interface that received the interest packet.

Further, upon receiving a data packet including a chunk, the transfer device determines an interface for transmitting the data packet based on the PIT, transmits the data packet from the determined interface, and updates the entry of the chunk from the PIT. delete. Note that the interface that transmits the data packet is the interface that received the interest packet requesting the chunk. Also, the forwarding device updates the CS when it caches the chunks contained in the received data packets.

Thus, in a CCN, data packets containing chunks are sent to the interface that received the Interest packet requesting the chunks. Therefore, the chunk is forwarded in the reverse direction along the same route as the Interest packet requesting the chunk and delivered to the client device that requested the chunk.

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

There is usually not one path but multiple paths from a certain transfer device to a server device that publishes certain content. Therefore, Non-Patent Document 1 also discloses adding strategy information to the FIB. The strategy information disclosed in Non-Patent Document 1 will be described below. FIG. 1 shows a CCN operated by an operator. 2 also shows the FIB of the transfer device 91 of FIG.

A chunk name is usually formed by adding a chunk number to a content name. For example, if the content with the content name "/Ca/olympic/soccer/Japan-US/" is divided into 10000 chunks, the chunk names of the chunks that make up this content are usually "/Ca/olympic/ soccer/Japan-US/1"~"/Ca/olympic/soccer/Japan-US/10000". The first part of the content name is usually information (name) specifying the server device. For example, the content name specifies a content whose file name is "Japan-US" in the "soccer" folder in the "olympic" folder of the server device specified by "Ca".

Thus, the server devices holding chunks with a common prefix are usually the same, and the chunk name prefix is used to reduce the number of entries in the FIB. In the FIB of FIG. 2, "/Ca/" in the chunk name field means any chunk name starting with "/Ca/". Similarly, "/Cb/" in the chunk name field means any chunk name starting with "/Cb/".

In the configuration of FIG. 1, a server device that publishes content with an arbitrary chunk name starting with "/Ca/" and a server device that publishes content with an arbitrary chunk name starting with "/Cb/" , the transfer device 91 needs to transfer the interest packet to the transfer device 95 . Here, in order for the transfer device 91 to transfer an Interest packet to the transfer device 95 , it is necessary to send the Interest packet to the transfer device 92 or the transfer device 93 . The transfer device 91 is connected to the transfer device 92 via its interface (IF) #1, and is connected to the transfer device 93 via its IF #2.

Therefore, in the FIB of FIG. 2, as a transmission interface for an interest packet requesting an arbitrary chunk name starting with "/Ca/" and an arbitrary chunk name starting with "/Cb/", Both IF#1 and IF#2 are described.

Strategy information is information for specifying a determination criterion for determining an interface from which a transfer device actually transmits an Interest packet from among multiple interfaces described as transmission interfaces in the FIB. Information. More specifically, a plurality of predetermined decision criteria are set in the transfer device, and the strategy field of the FIB specifies which one of the plurality of decision criteria is to be used. Information is stored. For example, the decision can be based on selecting the interface with the fastest or slowest link speed. Alternatively, the decision criteria can be to select the interface with the highest or lowest traffic volume. Since the transfer device can determine the delay time from the transfer of the Interest packet to the reception of the data packet as a response to the Interest packet, the selection of the interface with the shortest delay time is used as a decision criterion. can do. In FIG. 2, decision criterion Sa is used for any chunk whose name starts with "/Ca/", and decision criterion Sb is used for any chunk whose name starts with "/Cb/". Use is set as strategy information.

The strategy information is determined based on the operator's traffic management criteria for each content (or for each server device that publishes content), and is set in the FIB of each transfer device. Therefore, the same strategy information is set for each transfer device. That is, the FIBs of the transfer devices 92 to 97 also use the decision criterion Sa for any chunk whose name starts with "/Ca/", and any chunk whose name starts with "/Cb/". Strategy information indicating that the decision criterion Sb is used is set for the chunk. This is because if the determination criteria for the same content differ for each transfer device, the traffic management criteria determined by the operator will not be met. Therefore, in the FIBs of the transfer devices 91 to 96 in FIG. 1, the transfer destination interface differs for each transfer device, but the same strategy information is set.

Therefore, if the operator changes the decision criteria for any chunk whose name starts with "/Ca/" from Sa to Sc, the operator has to update the FIBs of all transfer devices that it manages.

The present invention provides a technique for reducing operator management work for a content distribution system that transfers content request packets based on the content name of the content.

According to one aspect of the present invention, a transfer device of a content distribution system that transfers a request packet for requesting content based on the content name of the content is a plurality of communication interfaces, and includes at least one communication interface connected to a predetermined device. one communication interface and at least one second communication interface connecting with another transfer device; communication interface information and strategy information associated with the content name; and a plurality of decision criteria. wherein the communication interface information indicates one or more communication interfaces that are transmission candidates for the request packet requesting the content with the associated content name; Each of the determination criteria indicates a criterion for determining a communication interface for transmitting the request packet when there are a plurality of communication interfaces that are candidates for transmitting the request packet, and is determined by the communication interface information. indicates a decision criterion, among the plurality of decision criteria, to be used for determining a communication interface for transmitting the request packet requesting the content of the associated content name; When forwarding a first request packet requesting a first content with a first content name received from a communication interface, strategy information associated with the first content name determines a first decision criterion to be used according to the plurality of decision criteria. from one or more communication interfaces indicated by the communication interface information associated with the first content name, determining a first destination communication interface for transmitting the first request packet based on the first determination criterion; and processing means for including information indicating the first decision criterion as use decision criterion information in the first request packet and transmitting the information from the first transfer destination communication interface.

According to the present invention, it is possible to reduce operator's management work for a content distribution system that transfers content request packets based on the content name of the content.

Explanatory diagram of the task. Explanatory diagram of the task. The figure which shows the structure of the part which an operator operates among the content distribution systems by one Embodiment. FIG. 3 illustrates FIBs of a first forwarding device and a second forwarding device according to one embodiment; FIG. 4 is an explanatory diagram of processing in the first transfer device according to one embodiment; FIG. 2 is a configuration diagram of a first transfer device and a second transfer device according to one embodiment;

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more of the features described in the embodiments may be combined arbitrarily. Also, the same or similar configurations are denoted by the same reference numerals, and redundant explanations are omitted.

In the following, the present embodiment will be described assuming that the content delivery system (content delivery network) is a CCN. However, the present invention can be applied to any content distribution system that routes based on content name. In particular, the present embodiment will be described below in a form in which content is distributed in units of content fragments called chunks according to content distribution by CCN, but the present invention also applies to networks that distribute content without dividing it. can be applied. Therefore, chunks and chunk names in the following description can be replaced with content and content names.

FIG. 3 shows a network 30 operated by an operator in the content distribution system according to this embodiment. In this embodiment, two types of transfer devices are defined. The first transfer device 10 is a transfer device that is connected to a user device or a transfer device operated by another operator (hereinafter referred to as an external transfer device). Also, the second transfer device is a transfer device that is connected only to transfer devices within the network 30 and has no connection to user devices or external transfer devices.

4A shows the FIB held by the first transfer device 10, and FIG. 4B shows the FIB held by the second transfer device 20. FIG. The FIB has transmission interface information and strategy information associated with the chunk name (or its prefix). The transmission interface information is information indicating one or more interfaces that are candidates for transmission of Interest packets requesting chunks with associated chunk names. In addition, when there are multiple interfaces that are candidate transmission candidates for an Interest packet requesting a chunk with an associated chunk name, the strategy information sets a determination criterion for determining an interface for transmitting the Interest packet from multiple interfaces. Identifying information. The transmission interface information is set in the transmission interface field of the FIB and the strategy information is set in the strategy field of the FIB. Since the transmission interface information set in the transmission interface field differs for each transfer device, the values of the transmission interface field are omitted in FIGS. 4A and 4B.

The FIB held by the first transfer device 10 shown in FIG. 4A is the same as in FIG. On the other hand, as shown in FIG. 4B, the FIB held by the second transfer device 20 does not have a strategy field.

5(A) and 5(B) illustrate processing when the first transfer device 10 receives an Interest packet through an interface connected to a user device or an external transfer device and transfers the Interest packet. It is a diagram. FIG. 5A shows an interest packet received by the first transfer device 10 at the interface connecting the user device or the external transfer device. The interest packet indicates that the chunk name (Name) of the requested chunk is "/Ca/olympic/soccer/Japan-US/1".

The first transfer device 10 determines an FIB entry that matches the prefix of the chunk name of the received Interest packet, and selects an interface for transmitting the Interest packet based on the determination criteria indicated by the strategy field of the determined entry. decide. If there are multiple entries that match the prefix of the chunk name of the received Interest packet, the first transfer device 10 determines the interface for transmitting the Interest packet based on the entry with the longest matching length. .

From the FIB of FIG. 4A, the first transfer device 10 identifies the decision criterion Sa from the strategy field of the first entry, and according to the identified decision criterion Sa, a plurality of transmission interface fields indicated by the first entry. From the interface, determine the interface on which to send the Interest packet. Note that if the sending interface field of the first entry indicates only one interface, then this one interface is determined to be the interface to send the Interest packet, regardless of the decision criteria used. Then, the first transfer device 10 adds usage decision criterion information indicating the specified decision criterion Sa to the Interest packet, and transmits the interest packet from the decided interface. FIG. 4B shows an interest packet transmitted by the first transfer device 10. FIG. In FIG. 4B, information indicating the decision criterion Sa is added as use decision criterion information (Strategy).

Therefore, the second forwarding device 20 receives an Interest packet containing usage decision criteria information in addition to information indicating the requested chunk name. The second transfer device 20 determines an interface for transmitting the Interest packet from the transmission interfaces indicated by the FIB (FIG. 4(B)) based on the usage decision criteria information included in the Interest packet.

Note that when the first transfer device 10 receives an Interest packet from the second transfer device or another first transfer device 10, the first transfer device 10 transmits the Interest packet based on the usage determination criteria information included in the received Interest packet. Determine the interface and do not change the usage decision criteria information contained in the Interest packet during forwarding. That is, when the first transfer device 10 receives an interest packet from the second transfer device 20 or another first transfer device 10, it does not use the strategy information set in the FIB.

With the above configuration, when the operator changes the strategy information, it is sufficient to update only the FIB of the first transfer device 10, and it is not necessary to update the FIB of the second transfer device 20. FIG. Therefore, the amount of processing for changing strategy information can be reduced. Therefore, the operator's management work can be reduced.

FIG. 6 is a configuration diagram of the first transfer device 10 and the second transfer device 20. As shown in FIG. As shown in FIG. 6, the configurations of the first transfer device 10 and the second transfer device 20 are basically the same. However, the FIB held in the storage unit 3 is different as described above. Also, the processing in the processing unit 2 is different as described above.

First, each functional block will be described assuming that FIG. 6 is the first transfer device 10 . The interface unit 1 has multiple interfaces (multiple communication interfaces). At least one of each interface terminates a link connecting a user device or an external transport device. Also, at least one of each interface terminates a link connecting to the second transfer device 20 or another first transfer device 10 .

The storage unit 3 has determination criterion information. The determination criterion information is information describing specific processing contents for determining an interface for transmitting an Interest packet from a plurality of interfaces for each of a plurality of determination criteria. In addition, the storage unit 3 has PIT, FIB and CS. As shown in FIG. 4A, the FIB of the transfer device 10 has strategy information. As described above, the strategy information is information specifying which of the plurality of decision criteria indicated by the decision criteria information is used to determine the interface for transmitting the interest packet. Although not clearly shown in FIG. 6, chunks to be cached are also stored in the storage unit 3 .

When transferring an Interest packet received from a user device or an external transfer device, the processing unit 2 specifies a decision criterion to be used based on the strategy information of the FIB, and selects an interface for transmitting the Interest packet according to the specified decision criterion. decide. Then, use decision criterion information indicating the specified decision criterion is added to the interest packet, and the interest packet is transmitted from the decided interface. When forwarding an Interest packet received from the first transfer device 10 or the second transfer device 20, the interface for transmitting the Interest packet is determined based on the usage decision criteria information included in the Interest packet. At this time, the usage decision criteria information included in the received interest packet is not changed.

Next, each functional block when FIG. 6 is assumed to be the second transfer device 20 will be described. Only changes from the first transfer device 10 shown in FIG. 6 will be described below. The interface section 1 has a plurality of interfaces. Each interface terminates a link connecting to the first transfer device 10 or the second transfer device 20 . As such, the second forwarding device 20 does not have a link to connect it to a user device or an external forwarding device. Also, the FIB does not include strategy information, as shown in FIG. 4(B).

When forwarding an Interest packet, the processing unit 2 determines an interface for transmitting the Interest packet based on the usage determination criteria information included in the Interest packet. Also, during transfer, the usage decision criteria information included in the received Interest packet is not changed.

In this embodiment, the first transfer device 10 is a transfer device connected to an external transfer device or a user device. However, when the external transfer device also performs the process of adding the usage decision criteria information to the Interest packet, the first transfer device 10 is a transfer device connected to at least one user device, and the second transfer device 20 is an operator The transfer device can be configured to be connected only to other transfer devices regardless of whether the transfer device is different or not.

In addition, when the first transfer device 10 and the second transfer device 20 according to the present invention are executed by one or more processors of a device having one or more processors, the devices are transferred to the first transfer device 10 or the second transfer device 20. , can be implemented by a program that causes the second transfer device 20 to operate. These computer programs can be stored in a computer-readable storage medium or distributed via a network.

The invention is not limited to the above embodiments, and various modifications and changes are possible within the scope of the invention.

1: interface unit, 3: storage unit, 2: processing unit

Claims (6)

A transfer device of a content delivery system that transfers a request packet requesting content based on the content name of the content,
a plurality of communication interfaces, the plurality of communication interfaces having at least one first communication interface connected to a predetermined device and at least one second communication interface connected to another transfer device;
A holding means for holding communication interface information and strategy information associated with the content name, and information indicating a plurality of decision criteria, wherein the communication interface information requests content with the associated content name. indicating one or more communication interfaces that are candidates for transmission of the request packet, wherein the plurality of determination criteria are each determined by the communication interface information, when there are a plurality of communication interfaces that are candidates for transmission of the request packet; indicating a criterion for determining a communication interface for transmitting the request packet, wherein the strategy information is a communication interface for transmitting the request packet requesting the content of the associated content name among the plurality of determination criteria; said holding means indicating a decision criterion used to determine the
When forwarding a first request packet requesting a first content with a first content name received from the first communication interface, strategy information associated with the first content name determines the first decision criteria to be used in the plurality of and determining a first transfer destination communication interface to which the first request packet is transmitted from one or more communication interfaces indicated by the communication interface information associated with the first content name based on the first determination criterion. processing means for determining, including information indicating the first determination criterion as usage determination criterion information in the first request packet and transmitting the information from the first transfer destination communication interface;
A transfer device comprising: When transferring a second request packet requesting a second content having a second content name received from the second communication interface, the processing means, based on the use determination criteria information included in the second request packet, uses a second destination communication interface for determining a second determination criterion to be used from the plurality of determination criteria, and transmitting the second request packet from one or more communication interfaces indicated by communication interface information associated with the second content name; is determined based on the second determination criterion, and the second request packet is transmitted from the second destination communication interface. 3. The transfer device according to claim 1, wherein said predetermined device is a user device. 4. The transfer device according to claim 1, wherein said predetermined device is a transfer device of a content distribution system operated by an operator different from the operator of said content distribution system. A transfer device of a content delivery system that transfers a request packet requesting content based on the content name of the content,
a plurality of communication interfaces that connect with other transfer devices;
holding means for holding communication interface information associated with the content name and information indicating a plurality of decision criteria, wherein the communication interface information is the request packet requesting the content with the associated content name and the plurality of determination criteria are each determined by the communication interface information, and if there are a plurality of communication interfaces that are candidates for transmitting the request packet said holding means indicating criteria for determining a communication interface to transmit a
When transferring a first request packet requesting a first content having a first content name received, the first decision criterion to be used is selected from the plurality of decision criteria based on use decision criterion information included in the first request packet. determine, based on the first determination criteria, a transfer destination communication interface to which the first request packet is to be transmitted from one or more communication interfaces indicated by the communication interface information associated with the first content name; A transfer device that transmits a request packet from the transfer destination communication interface. When executed on said one or more processors of a device having one or more processors, causing said device having one or more processors to act as a transfer device according to any one of claims 1 to 5. A program characterized by

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