JP6367732B2 - Transfer device and transfer method - Google Patents

Description

  The present invention relates to a transfer device and a transfer method.

  In recent years, a technology for virtualizing a service providing function (SF: Service Function) in which a server provides various services to a user terminal on a cloud or the like is known. When such a service providing function is virtualized, a technology for realizing flexible cooperation between a plurality of SFs is required. For this reason, a transfer system that analyzes a packet from a user terminal at the entrance of a network and controls a path for transferring the packet between SFs for each user or for each processing content has been studied.

  As a method for realizing such a transfer system, a technique for routing a packet from a user in service units or flow units, such as SFC (Service Function Chaining) or Open Flow, is known. For example, in SFC, a label for identifying a service is assigned to a packet, and routing based on the label is provided. The label has a different ID for each service, and a transfer function unit (SFF: Service Function Forwarder) that transfers a packet transmitted and received between SFs includes a label ID for identifying a transfer path, a packet transfer destination, Are stored in association with each other. When receiving the packet, the transfer function unit determines the next transfer destination from the ID indicated by the label of the received packet, and transfers the packet. If the destination is SF, the SF performs service processing and transfers the packet to the transfer function unit. The above operation is repeated, the packet passes through all the required SFs, the label is removed, and the packet is transferred to the original destination.

“Draft-ietf-sfc-architecture-02” [online], September 20, 2014, [December 10, 2014 search], Internet (https://tools.ietf.org/html/draft-ietf- sfc-architecture-02) “Open Flow Switch Specification Version 1.4.0” [online], October 14, 2013, [December 10, 2014 search], Internet (https://www.opennetworking.org/images/stories/downloads/sdn- resources / onf-specifications / openflow / openflow-spec-v1.4.0.pdf)

  However, in the above-described conventional technology, when a route branching to a transfer route is generated due to the addition of a new service function, there is a problem that all settings of the transfer function unit that performs processing before and after the branch must be changed.

  For example, when adding a second route that branches from the first route and joins again as a packet transfer route, the transfer function unit that is the branch point of the transfer route uses the packet transferred via the first route as A label having a different ID is assigned to a packet transferred through the second route. For this reason, the transfer function unit on the same route before and after the first route and the second route branch are transferred to the same transfer function unit regardless of whether the packet received from each transfer route is transferred to the same transfer function unit. Each label indicating the transfer path must be stored.

  The present invention has been made to solve the above-described problems of the prior art, and provides a transfer device and a transfer method capable of suppressing the number of transfer function units whose settings are changed even when a transfer path is added. The purpose is to do.

  In order to solve the above-described problems and achieve the object, the transfer device includes a receiving unit that receives a packet having an identifier indicating a transfer route of the packet and having a hierarchical structure based on a branch of the transfer route. An extracting unit that extracts a value up to a predetermined layer among identifiers assigned to the packet received by the receiving unit, a transfer destination of the packet, and at least the predetermined layer among identifiers attached to the packet A specifying unit that identifies a transfer destination associated with the value extracted by the extraction unit, and a transfer destination that the specifying unit specifies a packet received by the receiving unit. And a processing unit that transfers the data.

  Further, the transfer method is a transfer method executed by the transfer device, and includes a reception step of receiving a packet assigned with an identifier having a hierarchical structure based on a branch of the transfer path, which is an identifier indicating a transfer path of the packet. An extraction step for extracting values up to a predetermined layer from the identifiers assigned to the packet received in the reception step, a transfer destination of the packet, and at least the predetermined layer among identifiers assigned to the packet A specifying step for identifying a transfer destination associated with the value extracted in the extraction step with reference to a correspondence table in which the value of the extraction step is associated with, and a transfer destination specifying the packet received in the reception step in the specifying step And a processing step of transferring to the device.

  The specific device, the transfer device, and the transfer method disclosed in the present application can suppress the number of transfer function units whose settings are changed even if a branch occurs in the transfer path.

FIG. 1 is a configuration diagram illustrating an overview of a service providing network according to an embodiment. FIG. 2 is an explanatory diagram illustrating an example of a flow of processing executed by the transfer function unit and SF according to the embodiment. FIG. 3 is an explanatory diagram illustrating an example when a new transfer path is added. FIG. 4 is a diagram illustrating an example of processing executed by the transfer function unit according to the embodiment. FIG. 5 is a diagram illustrating an example of a functional configuration included in the identification function unit according to the embodiment. FIG. 6 is an explanatory diagram illustrating an example of a service correspondence table according to the embodiment. FIG. 7 is a diagram illustrating an example of a header according to the embodiment. FIG. 8 is a diagram illustrating an example of a functional configuration of the transfer function unit according to the embodiment. FIG. 9 is a diagram illustrating an example of information stored in the destination correspondence table according to the embodiment. FIG. 10 is a diagram illustrating another example of information stored in the destination correspondence table according to the embodiment. FIG. 11 is a diagram illustrating an example of information stored in the next process correspondence table according to the embodiment. FIG. 12 is a diagram illustrating another example of information stored in the next process correspondence table according to the embodiment. FIG. 13 is an explanatory diagram illustrating an example of processing in which the transfer function unit according to the embodiment updates transfer information. FIG. 14 is a flowchart illustrating a flow of processing executed by the identification function unit according to the embodiment. FIG. 15 is a flowchart illustrating a flow of processing executed by the transfer function unit according to the embodiment. FIG. 16 is an explanatory diagram illustrating another example of processing in which the transfer function unit updates transfer information.

  In the following embodiment, the configuration and processing flow of the transfer function unit according to the embodiment will be described, and then the effects of the embodiment will be described last.

[Embodiment]
Hereinafter, embodiments of a service providing network having a transfer function unit disclosed in the present application will be described. The following embodiments are merely examples, and do not limit the technology disclosed by the present application. Moreover, you may combine suitably embodiment shown below and its modification in the range which does not contradict.

(Service providing network configuration)
First, the configuration of a service providing network 1 having a transfer function unit, which is an example of a transfer device, will be described with reference to FIG. FIG. 1 is a configuration diagram illustrating an overview of a service providing network according to an embodiment. In the example illustrated in FIG. 1, the service providing network 1 includes a user terminal 2, a server device 3, and a cloud network 10.

  The user terminal device 2 is a server device that transmits a packet to be transmitted to the server device 3 to the cloud network 10, and is an information processing device such as a PC (Personal Computer), for example.

  When receiving a packet from the cloud network 10, the server device 3 is a server device that executes various processes based on information stored in the packet. For example, the server device 3 provides various services to the user who uses the user terminal 2 based on the information stored in the received packet.

  The cloud network 10 is a network that realizes a virtual service providing function in cooperation with a plurality of servers. For example, when receiving a packet from the user terminal 2, the cloud network 10 executes a predetermined process according to the data stored in the received packet, and transmits the packet storing the execution result of the process to the server device 3. .

  Hereinafter, the configuration of the cloud network 10 will be described. The cloud network 10 includes an identification function unit 11, a plurality of transfer function units 12a to 12e, SF_A 13a, SF_B 13b, SF_C 13c, SF_D 13d, and SF_E 13e. Each transfer function unit may be connected directly or via a network.

  The transfer function unit 12a is connected to the transfer function units 12b to 12e, the transfer function unit 12b is connected to the transfer function units 12a and 12c to 12e, and the transfer function unit 12c is connected to the transfer function units 12a, 12b, and 12e. The transfer function unit 12d is connected to the identification function unit 11 and the transfer function units 12a, 12b, and 12e. The transfer function unit 12a is connected to SF_A 13a and SF_D 13d, the transfer function unit 12b is connected to SF_B 13b, the transfer function unit 12c is connected to SF_C 13c and the server apparatus 3, and the transfer function unit 12e is connected to SF_E 13e. Is done.

  In the following description, a set of the transfer function unit 12a and SF_A 13a is a service unit_A 14a, a set of the transfer function unit 12b and SF_B 13b is a service unit_B 14b, a set of the transfer function unit 12c and SF_C 13c is a service unit_C 14c, and the transfer function unit 12a And SF_D13d are described as service unit_D14d, and the transfer function unit 12e and SF_E13e are described as service unit_E14e.

  In the following description, the transfer function units 12a to 12e are collectively referred to as the transfer function unit 12, and SF_A 13a, SF_B 13b, SF_C 13c, SF_D 13d, and SF_E 13e are collectively referred to as SF13. In the following description, service unit_A 14a, service unit_B 14b, service unit_C 14c, service unit_D 14d, and service unit_E 14e are collectively referred to as service unit 14.

  The identification function unit 11 is a gateway device located on the user terminal 2 side of the cloud network 10 and is realized by an information processing device such as a server. The transfer function unit 12 is a transfer device that transfers packets received from the user terminal 2 at any time and outputs the packets to the server device 3, for example, a network having an NP (Network Processor) and / or a CPU (Central Processing Unit). Realized by the device. The SF 13 is a device that executes various service processes using data stored in a received packet, and is realized by an information processing device such as a server device, for example.

(Outline of processing)
Hereinafter, the flow of processing executed by the identification function unit 11, the transfer function unit 12, and the SF 13 will be described with reference to FIG. FIG. 2 is an explanatory diagram illustrating an example of a flow of processing executed by the transfer function unit and SF according to the embodiment. In the example illustrated in FIG. 2, an example of a process of transferring a packet received from the user terminal 2 through a transfer path via SF_A 13a and SF_B 13b is described.

  For example, in the example illustrated in FIG. 2, the identification function unit 11 performs processing described below (step S1). Specifically, when receiving a packet from the user terminal 2, the identification function unit 11 analyzes the received packet and identifies the type of the packet. Here, the packet type is a processing flow of data stored in the packet, a packet transmission source user, or the like. Further, the identification function unit 11 determines a route according to the type of the identified packet, and as shown in FIG. 2A, a label (route ID) indicating the determined route and a transfer connected to the SF_A 13a. An IP header addressed to the function unit 12a is added to create a tunnel. Then, the identification function unit 11 transmits the tunneled packet to the transfer function unit 12a.

  On the other hand, when receiving the tunneled packet, the transfer function unit 12a refers to the label of the received packet, and when the SF_A 13a performs processing on the transfer path indicated by the referenced label, transmits the received packet to the SF_A 13a. (Step S2). In this case, the SF_A 13a executes processing using the received packet, stores the processing result in the received packet, and returns it to the transfer function unit 12a (step S3). Then, the transfer function unit 12a refers to the label of the packet received from the SF_A 13a, specifies the transfer function unit 12b that is the next destination of the SF_A 13a on the transfer path indicated by the label, adds the IP header to the packet, and transmits the packet. (Step S4).

  When the transfer function unit 12b receives the packet, the transfer function unit 12b refers to the label of the received packet, and when the SF_B 13b executes processing on the transfer path indicated by the referenced label, the transfer function unit 12b transmits the received packet to the SF_B 13b (step S5). ). In this case, the SF_B 13b executes processing using the received packet, stores the processing result in the received packet, and returns it to the transfer function unit 12b (step S6). Then, the transfer function unit 12b refers to the label of the packet received from the SF_B 13b, specifies SF_C 13c that executes the process next to SF_B 13b on the transfer path indicated by the label, and the transfer function unit 12c connected to the specified SF_C 13c. An IP header is attached to the packet and transmitted (step S7).

  The transfer function units 12c to 12e execute the same process as the transfer function units 12a and 12b, and the SF_C 13c to SF_E 13e execute the same process as the SF_A 13a and SF_B 13b. For this reason, the cloud network 10 can implement SFC using a packet received from the user terminal 2.

(Example of route addition)
Here, there is a case where a new transfer path via a new SF is added. For example, FIG. 3 is an explanatory diagram illustrating an example when a new transfer path is added. In the example illustrated in FIG. 3, the route ID “123” is assigned to the main transfer route that passes through the service unit_A 14a, the service unit_B 14b, the service unit_C 14c, and the service unit_D 14d.

  Here, when the service unit_E14e is added after the service unit_B14b and a route passing through the service unit_A14a, the service unit_B14b, the service unit_E14e, and the service unit_C14c is added, a new route ID “124” is added as such a route. Need to be set additionally. In such a case, in the related art, it is necessary to add the route ID “124” to the setting of the service unit_A 14a, the service unit C14c, and the service unit D14d before and after the service unit_B 14b that is a branch point.

(Processing executed by the transfer function unit 12)
Therefore, the transfer function unit 12 executes the following processing. For example, FIG. 4 is a diagram illustrating an example of processing executed by the transfer function unit according to the embodiment. As shown in FIG. 4, each transfer function unit 12 has a hierarchical structure based on the branch of the transfer route, and sets a lower layer value for the route ID every time the transfer route branches. When each transfer function unit 12 refers to the route ID of the received packet, the transfer function unit 12 refers to the hierarchical value based on how many times the transfer route in which the device is installed branches from the main transfer route. The packet is transferred to the transfer destination associated with the referenced value.

  For example, the identification function unit assigns a route ID “123-00” or “123-01” to the packet based on the identification result, and transfers the packet to the service unit_A 14a. The service unit_A 14a refers to “123”, which is the first three digits, of the route ID assigned to the received packet (step S10). Then, the service unit_A 14a transfers the received packet to the transfer destination service unit_B 14b associated with the referenced route ID “123”.

  On the other hand, the service unit_B 14b refers to “123”, which is the first three digits, of the route ID assigned to the received packet (step S11). If the transfer destination is not uniquely determined by the first three digits, the next two digits are referred to determine the destination, and the transfer is transferred to the service unit_C 14c.

  Here, the service unit_E14e is installed in a transfer path branched once from the main transfer path. Therefore, the service unit_E 14e refers to values up to the highest layer and the next layer in the route ID. As a specific example, the service unit_E 14e refers to “123-01”, which is the first six digits, of the route ID assigned to the received packet (step S12). Then, the service unit_E14e transfers the packet to the transfer destination service unit_C14c associated with the referred route ID “123-01”.

  As a result, the service unit_C 14c receives the packet with the route ID “123-00” and the packet with the route ID “123-01”. Here, in a packet transferred through the sub transfer path, a path ID in which a value indicating the main transfer path is stored in the highest layer and a value indicating the sub transfer path is stored in the lower layer Is granted. When such a route ID is given, even if the number of route ID layers increases depending on the packet transfer route, the value stored in each layer is not changed. For this reason, the service unit _C 14c installed on the main transfer route does not need to change the setting when transferring the packet using only the value stored in the highest layer among the route IDs.

  For example, the service unit_C 14c refers to the first three-digit value “123” in the route ID assigned to the received packet (step S13). Then, the service unit_C 14c transfers the packet to the transfer destination service unit_D 14d associated with the referenced path ID “123”. Similarly, the service unit_D 14d refers to the first three-digit value “123” in the route ID assigned to the received packet (step S14), and then sends the packet to the transfer destination associated with the referenced value. Forward.

  As described above, the transfer function unit 12 receives a packet to which a path ID having a hierarchical structure based on a branch of the transfer path is attached. In addition, the transfer function unit 12 extracts values up to a predetermined hierarchy from the route IDs attached to the packets. Then, the transfer function unit 12 refers to the destination correspondence table in which the transfer destination of the packet is associated with the value up to a predetermined layer among the route IDs attached to the received packet, and the value of the extracted route ID The transfer destination associated with is identified. Thereafter, the transfer function unit 12 transfers the received packet to the specified transfer destination.

  For this reason, the transfer function unit 12 can make the setting change of the transfer function unit 12 unnecessary even when a transfer path is added. For example, the transfer function unit 12 can add the route indicated by the route ID “124” without changing the setting of the transfer function unit arranged on the route indicated by the route ID “123”. Moreover, since the transfer function part 12 does not require a setting change, it can suppress the increase in the control signal transmitted with a setting change.

(Example of functional configuration of the identification function unit 11)
Hereinafter, an example of the functional configuration of the identification function unit 11 and the transfer function unit 12 that realize the above-described processing will be described. In the following description, an example in which the identification function unit 11 and the transfer function unit 12 transfer a packet using an IP (Internet Protocol) address will be described, but the embodiment is not limited to this. For example, a packet may be transferred using an MPLS (Multi Protocol Label Switching) label or a MAC (Media Access Control) address. That is, the identification function unit 11 and the transfer function unit 12 may transfer a packet on a network having an arbitrary specification without depending on the specification of the lower network.

  First, an example of the functional configuration of the identification function unit 11 will be described. For example, FIG. 5 is a diagram illustrating an example of a functional configuration included in the identification function unit according to the embodiment. In the example illustrated in FIG. 5, the identification function unit 11 includes a control unit 20 and a storage unit 21. The control unit 20 includes a communication unit 23, an analysis unit 24, and a specifying unit 25. The storage unit 21 stores a service correspondence table 22.

  The service correspondence table 22 stores the service contents related to the packet received from the user terminal 2 and the route ID of the transfer route for transferring the received packet in association with each other. For example, FIG. 6 is an explanatory diagram illustrating an example of a service correspondence table according to the embodiment. As shown in FIG. 6, the service correspondence table 22 stores services, route IDs, and destinations in association with each other.

  Here, the service is the content of the service related to the packet, and for example, information for identifying the content of the service such as “service A”, “service B”, “service C”, “service D” is stored. The In the route ID, a route ID indicating a transfer route of a packet related to the associated service is stored. For example, a hierarchical structure based on a branch such as “100”, “123”, “124”, “125”. Is stored. Information indicating the transfer destination of the packet is stored in the destination, and for example, “192.168.1.1” to “192.168.1.4”, which are IP addresses of the transfer destination, are stored.

  It goes without saying that information other than the information shown in FIG. 6 can be stored in the service correspondence table 22. For example, when the specification of the lower network is MPLS, the label assigned to the transfer function unit serving as the transfer destination is stored in the destination. That is, it is assumed that there is reachability between the transfer function units 12, and any information can be adopted as the destination as long as the information identifies each transfer function unit 12.

  Returning to FIG. 5, the description will be continued. The communication unit 23 transmits and receives packets to and from the user terminal 2 and the transfer function unit 12. For example, when receiving a packet from the user terminal 2, the communication unit 23 outputs the received packet to the analysis unit 24. In addition, when receiving a packet from the specifying unit 25, the communication unit 23 transmits the received packet to the transfer function unit 12 indicated by the destination.

  The analysis unit 24 analyzes the packet received from the user terminal 2. For example, the analysis unit 24 analyzes the transmission source of the packet received from the user terminal 2 and the data stored in the packet, and determines what service the received packet is related to.

  The specifying unit 25 specifies the route ID of the transfer route for transferring the packet received from the user terminal 2 according to the determination result by the analysis unit 24. For example, when the packet received from the user terminal 2 is a packet related to “service A”, the specifying unit 25 refers to the service correspondence table 22 and sets the route ID “100” associated with “service A”. The destination “192.168.1.1” is specified. Then, the specifying unit 25 adds a label including the route ID “100” to the packet received from the user terminal 2 and adds a header including the destination “192.168.1.1”, thereby receiving the packet from the user terminal 2. Tunneled packets.

  Here, a packet may loop many times in the same transfer path due to a setting error of the transfer function unit 12 or the like. When such a loop state occurs, a large amount of addition is applied to the transfer function unit 12 in the path through which the packet loops, and a serious failure may occur. Therefore, the specifying unit 25 adds transfer information for detecting a loop in the transfer path to the header.

  For example, FIG. 7 is a diagram illustrating an example of a header according to the embodiment. For example, as illustrated in FIG. 7, the specifying unit 25 adds a header storing information such as “header basic information”, “route information”, “transfer information”, and “option information” to the packet.

  For example, the “header basic information” stores the length of the header, the protocol information of the subsequent packet, and the like, and “option information” stores various metadata used on the network. The specifying unit 25 stores the specified route ID in the “route information” in the header. Further, as illustrated in FIG. 7A, the specifying unit 25 stores a predetermined value for indicating the number of hops on the route in the “transfer information” in the header. Each transfer function unit 12 decrements or increments the value of transfer information each time a packet is received. When the transfer information value satisfies a predetermined condition, the transfer function unit 12 determines that all the SFs have been passed and removes the header, or determines that a loop has occurred and discards the packet. To do. In the following description, the value of transfer information may be described as “In”.

(Example of functional configuration of transfer function unit 12)
Next, an example of the functional configuration of the transfer function unit 12 will be described with reference to FIG. FIG. 8 is a diagram illustrating an example of a functional configuration of the transfer function unit according to the embodiment. As illustrated in FIG. 8, the transfer function unit 12 includes a control unit 30 and a storage unit 31. The storage unit 31 also stores a destination correspondence table 32 and a next processing correspondence table 33. The control unit 30 includes a communication unit 34, an extraction unit 35, a specifying unit 36, a determination unit 37, and a processing unit 38.

  In the destination correspondence table 32, information indicating the transfer destination of a packet and a value up to a predetermined hierarchy among path IDs assigned to the packet are stored in association with each other. For example, FIG. 9 is a diagram illustrating an example of information stored in the destination correspondence table according to the embodiment. In the example shown in FIG. 9, an example of information stored in the destination correspondence table 32a stored in the transfer function unit 12a installed in the main transfer path is described.

  For example, as shown in FIG. 9, in the destination correspondence table 32a, values up to the highest layer among the route IDs stored in the packet are associated with information (for example, IP address) indicating the destination of the packet. Stored. For example, in the example illustrated in FIG. 9, the route correspondence table 32 a stores the route ID “100” and the destination “192.168.1.11” in association with each other, and the route ID “123” and the destination “192. 168.1.12 ”is stored in association with each other, and the route ID“ 124 ”and the destination“ 192.168.1.13 ”are stored in association with each other.

  On the other hand, FIG. 10 is a diagram illustrating another example of information stored in the destination correspondence table according to the embodiment. In the example shown in FIG. 10, an example of information stored in the destination correspondence table 32e stored in the transfer function unit 12e installed on the sub transfer path is described.

  As shown in FIG. 10, in the destination correspondence table 32e, the highest layer and the values up to the next layer among the route IDs stored in the packet are stored in association with the transfer destination of the packet. That is, since the transfer function unit 12e is installed on a sub transfer path that branches once from the main transfer path, the value of the highest hierarchy and the next hierarchy in the path ID are set as the transfer destination. Store in association with each other.

  For example, in the example illustrated in FIG. 10, the destination correspondence table 32e stores the route ID “100-01” and the destination “192.168.1.15” in association with each other, and the route ID “123-01”. The destination “192.168.1.17” is stored in association with each other, and the route ID “124-01” and the destination “192.168.1.18” are stored in association with each other.

  It goes without saying that information other than the information shown in FIGS. 9 and 10 can be stored in the destination correspondence table 32. For example, the destination correspondence table 32 of the transfer function unit 12 installed on the transfer path branched from the sub transfer path stores, for example, a three-layer path ID such as “100-01-01”. . Further, when the received packet is transferred to the SF 13, the destination correspondence table 32 stores the destination of the SF 13 and the destination of the transfer function unit 12 to be the next packet transfer destination in association with the same route ID. Will be.

  Returning to FIG. 8, the description will be continued. In the next processing correspondence table 33, the contents of processing executed according to the value of the transfer information are stored for each route ID. For example, FIG. 11 is a diagram illustrating an example of information stored in the next process correspondence table according to the embodiment. In the example shown in FIG. 11, an example of information stored in the next processing correspondence table 33a stored in the transfer function unit 12a installed in the main transfer path is described.

  For example, as shown in FIG. 11, the next processing correspondence table 33 includes a route ID, a determination formula for determining the hop number on the route, and a process executed when the determination formula is satisfied. Are stored in association with each other. For example, in the example illustrated in FIG. 11, the route IDs “100”, “123”, and “124” are associated with the determination formula “In <10” and the process “transfer to SF_A”. Here, the determination formula “In <10” indicates that it is determined whether or not the value of the transfer information is less than 10. The process “transfer to SF_A” transfers to SF_A when the determination formula is satisfied. Indicate.

  On the other hand, FIG. 12 is a diagram illustrating another example of information stored in the next process correspondence table according to the embodiment. In the example shown in FIG. 12, an example of information stored in the next process correspondence table 33e stored in the transfer function unit 12e installed on the sub transfer path is described.

  As illustrated in FIG. 12, the next processing correspondence table 33 e includes the route IDs “100-01”, “123-01”, and “124-01”, the determination formula “In <31”, and the processing “SF_E”. Are stored in association with each other.

  It goes without saying that information other than the information shown in FIGS. 11 and 12 can be stored in the next processing correspondence table 33. For example, the next processing correspondence table 33 only needs to store various types of processing to be performed on the received packet, such as “transfer to transfer function unit 12b” and “discard packet”. If there is no loop on the transfer path, the transfer function unit 12 may not perform the process using the next process correspondence table 33.

  That is, the service unit 14 installed on the main transfer path adds “10” to the value of the transfer information and outputs the value, and the service unit 14 installed on the sub transfer path sets the value of the transfer information. Add "1" and output. In this way, the service unit 14 adds different values to the transfer information when it is installed on the main transfer path and when it is installed on the sub transfer path. For this reason, the transfer function unit 12 hierarchizes the value of the transfer information together with the route ID.

  The transfer information is added (or subtracted) by SF or a function equivalent thereto. The value to be added (or subtracted) is different between the main route and the sub route, and the value is based on that the main route is larger than that of the sub route. Here, the transfer information may be updated by any one of the service units 14, and may be executed by the transfer function unit 12, for example.

  Here, the effect of the process of hierarchizing transfer information values will be described. For example, a plurality of SFs 13 may be connected to one transfer function unit 12. A specific example will be described. In the example shown in FIG. 1, since the transfer function unit 12a is connected to the SF_A 13a and the SF_D 13d, when the packet passes through the SF_A 13a and SF_D 13d, the same packet is passed multiple times. . However, since each transfer function unit 12 stores the path ID and the transfer destination in a one-to-one relationship, the same transfer function unit 12 cannot be routed a plurality of times.

  Also, regardless of the position where the transfer function unit 12 is installed, if the same numerical value is uniformly added to the value of the transfer information, the determination formula stored in the transfer function unit after the branch when the transfer path is branched All of these must be changed. Therefore, the SF 13 adds a different value to the value of the transfer information depending on whether the transfer path in which the apparatus is installed is a main transfer path or a sub transfer path. More specifically, the SF 13 adds a larger value in the case of the main transfer route than in the case of the sub transfer route. For example, the SF 13 adds “10” to the transfer information when the transfer path where the own apparatus is installed is the main transfer path, and when the transfer path where the own apparatus is installed is the sub transfer path. Then, “1” is added to the transfer information.

  Returning to FIG. 8, the description will be continued. The communication unit 34 transmits and receives packets to and from the other transfer function unit 12 and the SF 13. For example, the communication unit 34 receives from another transfer function unit 12 a packet to which a route ID having a hierarchical structure based on the branch of the transfer route is given.

  The extraction unit 35 extracts the value of the transfer information and the value up to a predetermined hierarchy from the route ID from the received packet label. Specifically, the extraction unit 35 extracts, from the route ID, a value up to a hierarchy corresponding to the number of branches of the transfer route in which the transfer function unit 12 is installed from the main transfer branch.

  For example, when the transfer function unit 12 is installed in the main transfer route, the extraction unit 35 extracts a value (for example, the first three digits) stored in the highest layer of the route ID. On the other hand, when the transfer function unit 12 is installed in the sub transfer path, the extraction unit 35 is configured to store the values stored in the highest layer and the next layer in the path ID (for example, the first 6 digits value). To extract.

  The specifying unit 36 transfers the received packet to the SF 13 connected to the own device based on the port that received the packet, the route ID extracted by the extraction unit 35, the value of the transfer information, and the like. Various processes for the received packet are specified such as transfer to the transfer function unit 12 or discard of the packet.

  For example, the specifying unit 36 searches the destination correspondence table 32 for a route ID that completely matches the value extracted from the route ID by the extraction unit 35. If the route ID that completely matches the value extracted from the route ID by the extraction unit 35 is stored in the destination correspondence table 32 as a result of the search, the specifying unit 36 selects the destination associated with the route ID. All are acquired and output to the processing unit 38. On the other hand, if the route ID that completely matches the value extracted from the route ID by the extraction unit 35 is not stored in the destination correspondence table 32 as a result of the search, the specifying unit 36 discards the received packet.

  The determination unit 37 determines whether or not the value of the transfer information extracted by the extraction unit 35 satisfies the conditional expression stored in the next processing correspondence table 33. For example, the determination unit 37 acquires a determination formula associated with the route ID extracted by the extraction unit 35 from the next processing correspondence table 33. Then, the determination unit 37 determines whether or not the transfer information value extracted by the extraction unit 35 satisfies the acquired determination formula. For example, when the acquired determination formula is “In <10”, the determination unit 37 determines whether or not the value of the transfer information extracted by the extraction unit 35 is smaller than “10”. Then, the determination unit 37 outputs the determination result to the processing unit 38.

  The processing unit 38 is at least one of discarding the received packet, removing the header, or transferring the packet to the original destination (server apparatus 3) according to the path ID extracted from the received packet. Run one. For example, the processing unit 38 receives the received packet and receives the destination from the specifying unit 36. In addition, the processing unit 38 receives a determination result from the determination unit 37. When the determination unit 37 determines that the value of the transfer information extracted by the extraction unit 35 satisfies the conditional expression stored in the next processing correspondence table 33, the processing unit 38 performs processing associated with the conditional expression. To forward the packet.

  For example, when the process associated with the conditional expression is “transfer to SF_A”, the processing unit 38 specifies the destination of “SF_A” from the destination specified by the specifying unit 36, and adds a header indicating the specified destination. By attaching to the packet, the packet is transferred to “SF_A”. On the other hand, when the processing associated with the conditional expression is “transfer to transfer function unit 12b”, the processing unit 38 specifies the destination of “transfer function unit 12b” from the destination specified by the specifying unit 36, and transfers A header indicating the destination of the functional unit 12b is added to the packet, and the packet is transferred. Here, any conventional technique can be applied to the destination specifying method.

  That is, the processing unit 36 transfers the packet to a transfer destination associated with the route ID, SF, or the like. In addition, when the specifying unit 36 instructs the processing unit 38 to transfer the packet to the original destination, the processing unit 38 removes the header storing the route ID and the packet destination before tunneling, that is, the server device 3 forwards the received packet.

  On the other hand, when the determination unit 37 determines that the value of the transfer information extracted by the extraction unit 35 does not satisfy all the conditional expressions stored in the next processing correspondence table 33, the processing unit 38 determines that a loop has occurred. And discard the packet. When a loop occurs, the processing unit 38 may remove the header from the received packet and transfer the packet to the destination of the packet before tunneling. In addition, the processing unit 38 may be set to execute a predetermined arbitrary operation when a loop occurs. In addition to the above-described processes, the processing unit 38 may execute such a process when an arbitrary process is associated with the conditional expression.

(Another example of processing executed by the transfer function unit 12)
Here, the transfer function unit 12 may perform packet transfer by executing the following processing. For example, the transfer function unit 12 stores a correspondence table in which the route ID, the determination formula, and the process are associated, that is, a correspondence table in which the destination correspondence table 32 and the next processing correspondence table 33 are combined. In such a case, the specifying unit 36 specifies a process associated with the route ID extracted by the extracting unit 35. And the determination part 37 determines whether the transfer information of the received packet satisfy | fills the determination formula matched with each process which the specific | specification part specified. Then, the processing unit 38 performs packet transfer, discarding, and the like in accordance with processing in which the determination unit 37 determines that the transfer information satisfies the determination formula.

  In other words, the transfer function unit 12 may be realized by an arbitrary process as long as it determines the packet processing based on the hierarchical route ID and the hierarchical route information.

(Example of processing for updating transfer information)
Next, an example of processing in which the transfer function unit 12 updates transfer information will be described with reference to FIG. FIG. 13 is an explanatory diagram illustrating an example of processing in which the transfer function unit according to the embodiment updates transfer information. In the example illustrated in FIG. 13, an example of processing in which each service unit 14 updates transfer information is described. In the following description, the service unit 14 installed on the main transfer path adds “10” to the transfer information, and the service unit 14 installed on the sub transfer path adds “1” to the transfer information. "Is added.

  For example, the identification function unit 11 outputs a packet given “0” as an initial value of the transfer information. In such a case, the service unit_A 14a determines whether or not the transfer information given to the received packet satisfies “In <10” (step S20). Then, when the transfer information given to the received packet satisfies “In <10”, the service unit_A 14a is set to “10” because the service unit_A 14a is installed on the main transfer path. Is added and transferred to the service unit_B 14b (step S21).

  On the other hand, the service unit_B 14b determines whether or not the transfer information given to the received packet satisfies “In <20” (step S22). Then, when the transfer information given to the received packet satisfies “In <20”, the service unit_B 14b is set to “10” because the service unit_B 14b is installed on the main transfer path. Is added to the service unit_C14c or the service unit_E14e (steps S23 and S24).

  Also, the service unit_E 14e determines whether or not the transfer information given to the received packet satisfies “In <30” (step S25). Then, when the transfer information given to the received packet satisfies “In <30”, the service unit_E 14e is set on the value of the transfer information because the service unit_E14e is installed on the sub transfer path. Is added and transferred to the service unit_C14c (step S26).

  On the other hand, the service unit_C 14c determines whether the transfer information given to the received packet satisfies “In <30” regardless of whether the transfer path of the packet is a main transfer path or a sub transfer path. Is determined (step S27). Then, when the transfer information given to the received packet satisfies “In <30”, the service unit_C 14c is set on the value of the transfer information because the service unit_C 14c is installed on the main transfer path. "Is added and transferred to the service unit_D 14d (step S28).

  Further, the service unit_D 14d determines whether or not the transfer information given to the received packet satisfies “30 ≦ In <40” (step S29). When the transfer information given to the received packet satisfies “30 ≦ In <40”, the service unit_D 14d has the service unit_D 14d installed on the main transfer path, so “10” is added and the packet is transferred (step S30).

  Thus, when the service unit 14 installed on the main transfer path is installed on the main transfer path, “10” is added to the transfer information, and the service unit 14 is set on the sub transfer path. If there is, “1” is added to the transfer information. Then, the transfer function unit 12 determines whether or not the value of the transfer information given to the received packet is smaller than the value obtained by adding “10” to the number of transfer function units that transferred the packet on the main transfer path. Determine.

  As described above, the service unit 14 adds different values on the main transfer path and the sub transfer path, that is, hierarchized values, to the transfer information. As a result, the transfer function unit 12 can determine whether or not a loop has occurred without changing the determination formula of the transfer function unit 12 after the branch.

  In the example shown in FIG. 13, the service unit 14 on the main transfer path adds the value “10” to the transfer information, and the service unit 14 on the sub transfer path uses the value “1” as the transfer information. Added. However, the embodiment is not limited to this. For example, when the value that the transfer function unit on the main transfer path adds to the transfer information is “X” and the value that the transfer function unit on the sub transfer path adds to the transfer information is “x”, “x” The value of “” may be a value smaller than “X”. In this case, the transfer function unit that transfers the nth packet on the main transfer path may determine whether or not the value of the transfer information given to the received packet is equal to or less than “nX”.

  Here, as values of “X” and “x”, when values in different places are set in decimal notation, the values of transfer information are hierarchized and are therefore included in the determination formula Setting of the threshold value can be facilitated. Also, when different values are set as the values of “X” and “x” in binary notation, whether or not a loop has occurred if only a predetermined bit value of the transfer information is read. Can be determined.

(Processing flow by the identification function unit 11)
Next, the flow of processing by the identification function unit 11 according to the embodiment will be described with reference to FIG. FIG. 14 is a flowchart illustrating a flow of processing executed by the identification function unit according to the embodiment. As illustrated in FIG. 14, the identification function unit 11 analyzes a packet received from the user terminal 2 and specifies a service related to the packet (step S <b> 101). Further, the identification function unit 11 adds a path ID and transfer information corresponding to the specified service to the header (step S102). Further, the identification function unit 11 sets a destination corresponding to the specified service (step S103). And the identification function part 11 outputs the received packet (step S104), and complete | finishes a process.

(Processing flow by the transfer function unit 12)
Next, the flow of processing by the transfer function unit 12 according to the embodiment will be described with reference to FIG. FIG. 15 is a flowchart illustrating a flow of processing executed by the transfer function unit according to the embodiment. For example, the transfer function unit 12 extracts transfer information and a route ID from the header of the received packet (step S201). Further, the transfer function unit 12 extracts a value from the top to a predetermined hierarchy from the route ID (step S202). Specifically, the transfer function unit 12 extracts values up to the hierarchy according to how many times the transfer path in which the apparatus is installed branches from the main transfer path.

  Then, the transfer function unit 12 determines whether or not the destination associated with the extracted value is registered in the destination correspondence table 32 (step S203), and if it is registered (step S203: Yes), The destination associated with the extracted value is set as the destination of the packet (step S204). Further, the transfer function unit 12 determines whether or not the value of the extracted transfer information satisfies the determination formula received in correspondence with the value extracted from the route ID (step S205). When the transfer function unit 12 determines that the extracted transfer information value satisfies the determination formula (step S205: Yes), the transfer function unit 12 transfers the packet (step S206) and ends the process.

  On the other hand, when the destination associated with the extracted value is not registered in the destination correspondence table 32 (step S203: No), the transfer function unit 12 sets the predetermined destination as the packet destination (step S207). Step S205 is executed. If the extracted transfer information value does not satisfy the determination formula (step S205: No), the transfer function unit 12 discards the packet (step S208) and ends the process.

  In the above description, an example of processing for executing packet transfer or packet discarding according to whether or not the extracted transfer information value satisfies the determination formula has been described. It is not limited. For example, the transfer function unit 12 sets a plurality of conditions, and depending on which condition the extracted transfer information value satisfies, the packet transfer, the packet discard, the header deletion, the original of the received packet You may perform the transfer to a transfer destination, and other arbitrary processes. In addition, the transfer function unit 12 may set a plurality of conditions for the transfer information value and the route ID value, and execute various processes according to which condition each value satisfies. .

(Effect of embodiment)
As described above, the transfer function unit 12 receives a packet having a path ID indicating a transfer path of a packet and having a path ID having a hierarchical structure based on a branch of the transfer path. In addition, the transfer function unit 12 extracts values up to a predetermined hierarchy from the route IDs assigned to the received packets. Then, the transfer function unit 12 refers to the destination correspondence table 32 in which the transfer destination of the packet is associated with the value up to at least a predetermined layer among the route IDs assigned to the received packet, and corresponds to the extracted value. Identifies the attached forwarding destination. Thereafter, the transfer function unit 12 transfers the received packet to the specified transfer destination.

  For this reason, even when a transfer route is added, the transfer function unit 12 can make it unnecessary to change the setting of the transfer function unit 12 in the added route. For example, in the case illustrated in FIG. 4, the service unit_C14c and the service unit_D14d after branching may have the path ID given to the received packet “123-00” or “123-01”. Only the highest value “123” of the route ID may be extracted, and the packet transferred to the transfer destination associated with the extracted value. For this reason, the transfer function unit 12 can eliminate the need to change the path ID stored in the service unit_C 14c or the service unit_D 14d.

  If the transfer function unit 12 cannot identify the transfer destination associated with the extracted value, the transfer function unit 12 removes the header storing the path ID and transfers the packet to the original transfer destination of the received packet. . For this reason, the transfer function unit 12 can continue the packet transfer even when the transfer destination is not specified.

  In addition, the transfer function unit 12 extracts values from the received route ID to a hierarchy corresponding to the number of transfer routes branched to the own device. Therefore, the transfer function unit 12 can extract a value necessary for specifying the transfer path of the packet from the path ID regardless of the number of transfer paths branched.

  In addition, the transfer function unit 12 updates the value of the transfer information given to the packet to a value obtained by adding a value corresponding to the number of transfer paths branched to the own device. Further, the transfer function unit 12 determines whether or not the value of the transfer information given to the packet is less than a predetermined threshold value. When the transfer function unit 12 determines that the value of the transfer information is smaller than the predetermined threshold value, the transfer function unit 12 transfers the received packet. When the transfer function unit 12 determines that the value of the transfer information is equal to or greater than the predetermined threshold value, Discards the received packet. For this reason, the transfer function unit 12 can make it unnecessary to change the determination formula stored in the transfer function unit 12 after the branch.

  Further, when the transfer function unit 12 is installed on the main transfer route, the transfer function unit 12 adds “X” to the value of the transfer information given to the received packet, and the sub-function branched from the main transfer route. If it is installed on the transfer path, “x” is added to the value of the transfer information given to the received packet. Then, the transfer function unit 12 sets a value obtained by adding “X” to the number of transfer apparatuses that transferred the received packet on the main transfer path until the packet is received as a predetermined threshold. For this reason, the transfer function unit 12 can make it unnecessary to change the determination formula stored in the transfer function unit 12 after the branch.

(Other embodiments)
Although the embodiments have been described so far, the disclosed invention may be implemented in various different forms other than the above-described embodiments. Therefore, other embodiments will be described below.

(Variation of processing to update transfer information)
The transfer function unit 12 described above adds a different value to the value of the transfer information depending on the number of installed transfer paths branched from the main transfer path. However, the embodiment is not limited to this. For example, when the transfer function unit 12 is installed on the main transfer path, the value of transfer information is set to a specific value “X” for the number n of transfer function units 12 that transferred packets on the main transfer path. May be updated to the integrated value.

  For example, FIG. 16 is an explanatory diagram illustrating another example of processing in which the transfer function unit updates transfer information. In the example shown in FIG. 16, “10” is adopted as the specific value “X”. For example, the identification function unit 11 outputs a packet given “0” as an initial value of the transfer information. In such a case, the service unit_A 14a determines whether or not the transfer information given to the received packet satisfies “In <10” (step S40). Then, if the transfer information given to the received packet satisfies “In <10”, the service unit_A 14a has the numbers “n = 1” and “X = 10” of the service units 14 that have transferred the packet so far. The value of the transfer information is changed to a value “10” obtained by integrating the above and the packet is transferred to the service unit_B 14b (step S41).

  On the other hand, the service unit_B 14b determines whether or not the transfer information given to the received packet satisfies “In <20” (step S42). When the transfer information given to the received packet satisfies “In <20”, the service unit_B 14b has transferred the packet so far because the service unit_B 14b is installed on the main transfer path. The transfer information value is changed to a value “20” obtained by integrating the number of service units 14 “n = 2” and “X = 10”, and the packet with the changed transfer information value is changed to service unit_C14c or service unit_e14e. (Steps S43 and S44).

  Here, the service unit_E 14e determines whether or not the transfer information given to the received packet satisfies “In = 20” (step S45). Then, when the transfer information given to the received packet satisfies “In = 20”, the service unit_E 14e is set on the value of the transfer information because the service unit_E14e is installed on the sub transfer path. Is added and transferred to the service unit_C14c (step S46).

  On the other hand, the service unit_C 14c determines whether the transfer information given to the received packet satisfies “In <30” regardless of whether the transfer path of the packet is a main transfer path or a sub transfer path. Is determined (steps S47 and S48). In addition, when the transfer information given to the received packet satisfies “In <30”, the service unit_C 14c has the service unit_C 14c installed on the main transfer path. The value of the transfer information is changed to a value “30” obtained by integrating the number “n = 3” and “X = 10” of the service units 14 that transferred the packet. Then, the service unit_C 14c transfers the packet whose transfer information value has been changed to the service unit_D 14d (step S49).

  Further, the service unit_D 14d determines whether or not the transfer information given to the received packet satisfies “In <40” (step S50). Then, when the transfer information given to the received packet satisfies “In <40”, the service unit_D 14d has the service unit_D 14d installed on the main transfer path. The value of the transfer information is changed to a value “40” obtained by integrating the number “n = 4” and “X = 10” of the service units 14 that transferred the packet. Then, the service unit_D 14d transfers the packet whose transfer information value has been changed (step S51).

  As described above, when the service unit 14 is installed on the main transfer path, the value of the transfer information given to the received packet is set to the number of transfer function units that transferred the packet on the main transfer path. Update a value obtained by adding a specific value “X” to “n”. Further, when the service unit 14 is set on the sub transfer path branched from the main transfer path, the value of the transfer information given to the received packet is smaller than the specific value “X”. Add “x”. Then, the transfer function unit 12 determines whether or not the value of the transfer information is smaller than the value obtained by adding the specific value “X” to the number “n” of transfer devices that transferred the packet on the main transfer path. .

  For this reason, the transfer function unit 12 can eliminate the need to change the determination formula stored in the transfer function unit after the branch. Further, in the method shown in FIG. 13, the number of service units 14 that can be added to the sub transfer path is up to “X−x”, but in the method shown in FIG. 16, the restriction can be solved. . However, in the method shown in FIG. 16, every time the sub transfer path and the main transfer path merge, the value of the transfer information updated in the sub transfer path is replaced. The information shown is lost.

(About decrement)
The transfer function unit 12 described above adds the value of “X” or “x” to the value of the transfer information. However, the embodiment is not limited to this. That is, the transfer function unit 12 may subtract (decrement) the value of “X” or “x” from the value of the transfer information. For example, in the transfer path illustrated in FIG. 13, the identification function unit 11 assigns “50” as the value of the transfer information. In such a case, the service unit_A 14a determines whether or not the value of the transfer information is less than “60”, and when it is determined that the value of the transfer information is less than “60”, the value “ Subtract "10" from "50" and transfer. Further, the service unit_B 14b determines whether or not the value of the transfer information is less than “50”, and when determining that the value of the transfer information is less than “50”, the service unit_B 14b starts from the value “40” of the transfer information. Subtract "10" and transfer.

  Further, the service unit_E 14e determines whether or not the value of the transfer information is less than “40”, and when determining that the value of the transfer information is less than “40”, the service unit_E 14e starts from the value “30” of the transfer information. Subtract "1" and transfer. Then, the service unit C_14c determines whether or not the value of the transfer information is “30” or less, and when it is determined that the value of the transfer information is “30” or less, the value “30” or “ Subtract "10" from 29 "and transfer.

  As described above, even when the transfer function unit 12 decrements the value of the transfer information, the transfer function unit 12 may decrement a different value between the main transfer path and the sub transfer path. By executing such processing, the transfer function unit 12 can detect a loop while making it unnecessary to change the determination formula stored in the transfer function unit 12 after the branch.

(About the scope of application)
In the above-described embodiment, the transfer function unit 12 transfers a packet as an SFF in the SFC. However, the embodiment is not limited to this. For example, the transfer function unit 12 may transfer a packet on an arbitrary network such as VXLAN (Virtual eXtensible Local Area Network). That is, the transfer function unit 12 can change the setting by using a hierarchical route ID and transfer information even when a transfer route is added by adding a common domain or a subdivided domain, for example. It is possible to reduce the number of transfer function units that perform.

  Although several embodiments have been described so far, the technology disclosed in the present application is not limited to these embodiments. That is, these embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made.

  For example, the specific form of distribution / integration of each device (for example, the form shown in FIG. 8) is not limited to the one shown in the figure, and all or a part thereof may be arbitrarily determined according to various loads or usage conditions. Functionally or physically distributed and integrated. For example, the communication unit 34 and the processing unit 38 may be integrated as one unit, and the transfer function unit 12 may be separated into the control unit 30 and the storage unit 31.

  In addition, among the processes described in the embodiments, all or a part of the processes described as being automatically performed can be manually performed.

  Further, the destination correspondence table 32 and the next processing correspondence table 33 may be stored in another storage device connected to the transfer function unit 12 via a network. In addition, each of the units 34 to 39 included in the control unit 30 may be included in different devices, and may be connected to a network to cooperate to realize the functions of the control unit 30 described above.

  These embodiments and modifications thereof are included in the invention disclosed in the claims and equivalents thereof as well as included in the technology disclosed in the present application.

DESCRIPTION OF SYMBOLS 1 Service provision network 2 User terminal 3 Server apparatus 10 Cloud network 11 Identification function part 12 Transfer function part 13 SF
14 service unit 20, 30 control unit 21, 31 storage unit 22 service correspondence table 23, 34 communication unit 24 analysis unit 25 identification unit 32 destination correspondence table 33 next processing correspondence table 34 communication unit 35 extraction unit 36 identification unit 37 determination unit 38 Processing part

Claims (7)

In a transfer device that transmits and receives packets,
An identifier indicating a transfer path of the packet, have a hierarchical structure based on the branch transfer path, every time the transfer path is branched, receives an identifier for setting a lower value in the hierarchical structure is assigned a packet A receiver,
An extraction unit that extracts a value up to a predetermined layer based on how many times the transfer path in which the own transfer device is installed branches from the main transfer path, from the identifier given to the packet received by the receiving unit;
Referring to the correspondence table that associates the packet transfer destination with the values assigned to the packet up to at least the predetermined layer, and identifies the transfer destination associated with the value extracted by the extraction unit A specific part to be
And a processing unit that transfers the packet received by the receiving unit to the transfer destination specified by the specifying unit.   The processing unit executes at least one of discarding the received packet, removing the identifier, or transferring the packet to the original destination according to the value extracted by the extraction unit. The transfer device according to claim 1.   The transfer device according to claim 1, wherein the extraction unit extracts values up to a hierarchy according to the number of branches of the transfer path up to the transfer device. A determination unit that determines whether or not a value of transfer information that is updated every time the packet is transferred is less than a predetermined threshold, which is transfer information given to the packet received by the receiving unit;
When the determination unit determines that the value of the transfer information is less than a predetermined threshold, the processing unit transfers the packet received by the reception unit, and the value of the transfer information becomes the predetermined threshold. The transfer device according to any one of claims 1 to 3, wherein the receiving unit performs a predetermined process on the packet received. The value of the transfer information is incremented by a first value every time it is transferred on a predetermined transfer path, and is smaller than the first value every time it is transferred on a transfer path branched from the predetermined transfer path. The second value is added,
The determination unit sets, as the predetermined threshold, a value obtained by adding the first value to the number of transfer devices that have transferred the packet on the predetermined transfer path before the transfer device receives the packet. The transfer apparatus according to claim 4, wherein: The value of the transfer information is updated to a value obtained by adding the first value to the number of transfer devices that transferred the packet on the predetermined transfer path when the value is transferred on the predetermined transfer path. When transferring on a transfer path branched from the transfer path, a second value smaller than the first value is added,
The determination unit sets, as the predetermined threshold, a value obtained by adding the first value to the number of transfer devices that have transferred the packet on the predetermined transfer path before the transfer device receives the packet. The transfer apparatus according to claim 4, wherein: A transfer method executed by a transfer device that transmits and receives packets ,
An identifier indicating a transfer path of the packet, have a hierarchical structure based on the branch transfer path, every time the transfer path is branched, receives an identifier for setting a lower value in the hierarchical structure is assigned a packet Receiving process;
An extraction step for extracting a value up to a predetermined hierarchy based on how many times the transfer route in which the own transfer device is installed branches from the main transfer route from the identifier given to the packet received in the reception step;
Referring to the correspondence table that associates the packet transfer destination with the values up to the predetermined hierarchy among the identifiers assigned to the packet, specifies the transfer destination associated with the value extracted in the extraction step Specific process to
And a processing step of transferring the packet received in the receiving step to the transfer destination specified in the specifying step.

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