JP4926763B2 - Packet transfer method and control device - Google Patents

Description

  The present invention relates to a packet transfer method in an overlay network.

  There is a distributed hash table (DHT) method as a method for scalable communication between nodes and data (content data, etc.) in an overlay network. In the Chord system, which is a typical example, a fixed-length ID (Identifier) value (identification number) is assigned to both the nodes constituting the network and the data arranged therein using a hash function. Each data is managed by the node having the closest ID value so that the data is distributed.

  At this time, the nodes are evenly arranged in the ID space according to the nature of the hash function. However, the interval between adjacent nodes in the ID space, that is, the interval of ID values between adjacent nodes in the ID space is not constant and varies. Since the expected value of the number of data arranged in each node is considered to be proportional to the interval of ID values between adjacent nodes, the variation in the interval causes a load bias between the nodes.

  As a method for alleviating this, for example, the following Non-Patent Document 1 proposes a method in which a plurality of ID values are assigned to one node and each load is operated as a virtual node to equalize the load. . By bundling a plurality of virtual nodes, variations in the interval of ID values between the nodes can be averaged, and the load unevenness of each physical node can be reduced.

“Chord: A Scalable Peer-to-Peer Lookup Service for Internet Applications”, Proc. ACM SIGCOMM, 2001

  However, according to the technique of the conventional Non-Patent Document 1, if n virtual nodes are assigned to one physical node, the total number of nodes participating in the system increases n times. The average number of transfers required for communication between a set of nodes increases approximately in logarithmic order with respect to the total number of nodes. Scalability is not lost because it is a gradual increase in logarithmic order. However, in a system that frequently searches the distributed hash table, the number of transfers greatly affects the network cost. It is desirable.

  On the other hand, in general, in the DHT system, when the number of inter-node links that can be used by each node for transfer is increased, the average number of transfers for a pair of inter-node communication decreases. Therefore, the average number of transfers can be suppressed by simply increasing the number of links. However, if the number of links is increased, the cost for maintenance and management also increases. Therefore, there is a limit to how to increase the number of links, and it is difficult to suppress the increase in the number of transfers.

  The present invention has been made in view of the above, and provides a packet transfer method and control device that realize inter-node communication with a small number of transfers without increasing the cost and without losing the load distribution effect provided by the virtual node. The purpose is to obtain.

  In order to solve the above-described problems and achieve the object, the present invention provides a unique identification number assigned to an identification number in a communication system that includes a control device including a plurality of virtual control devices and constitutes an overlay network. A packet transfer method in a virtual control device in which a management area in an identification number space is individually allocated based on the transfer number that is a transfer destination list based on the identification number, and A transfer information generation step that is held so as to be sharable among all virtual control devices belonging to the control device, and the virtual control device that has received the data among all the virtual control devices determines the final destination included in the received data. When the destination identification number indicated is not the management area of the own device, the transfer information held in a sharable manner is based on the destination identification number. And transfer destination selection step of selecting et transfer destination, the virtual controller which has received the data is characterized in that it comprises a and a transfer step of transferring the received data to the transfer destination and the selected.

  According to the present invention, since the transfer information is shared between the virtual nodes belonging to the same physical node, and the redundant portion of the transfer information is deleted, the load balancing effect brought about by the virtual node without increasing the cost There is an effect of realizing inter-node communication with a small number of transfers without impairing the above.

  Hereinafter, embodiments of a packet transfer method and a control device according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram illustrating a functional configuration example of a control device according to a first embodiment of the present invention. As shown in FIG. 1, the control device 1 according to the present embodiment includes a transmission processing unit 2 that transmits data to an external network, a reception processing unit 3 that receives data from the external network, and a virtual control device 5 that receives the received data. A common processing unit 4 that transfers to any one of -1 to 5-4, virtual control devices 5-1 to 5-4, and an interface 9 that connects the virtual control devices 5-1 to 5-4 Is done. The virtual control device 5-i (i = 1 to 4) includes an arithmetic processing unit 6-i that analyzes received data, a control information management unit 7-i that holds control information such as packet transfer information, A content management unit 8-i that holds data allocated to the own virtual node among the content data distributed on the overlay network.

  FIG. 2 is a diagram illustrating an example of an overlay network constructed by connecting the control device 1 according to the present embodiment and the communication terminals 10-1 to 10-5. In FIG. 2, control devices 1-1 to 1-5 each have the same functional configuration as the control device 1 shown in FIG. A logical communication path is set between each of the control devices 1-1 to 1-5, and one-way or two-way communication is possible. Further, for example, the control device 1-connected to the communication terminals 10-1 to 10-5 like the control device 1-1 and the communication terminal 10-1, the control device 1-3 and the communication terminal 10-2, respectively. A logical communication path is also set between 1 and 1-5, and one-way or two-way communication is possible.

  In the overlay network of the present embodiment, the Chord system is applied, and an ID (IDentifier) value is assigned to each node (here, a virtual control device) and each content data. Each data is managed by a virtual control device having the ID value closest to the ID value assigned to the data. It is assumed that the transmission / reception data in the present embodiment includes a destination ID indicating the final destination. Here, the destination ID is the ID of the content data that requests acquisition in the case of a content acquisition request, and in the case of control information (such as addition of a control device), the control device that is the final transmission destination of the control information ID.

  Here, in order to describe the operation of the control device 1 of the present embodiment, first, the operation will be described by taking a single control device that does not perform virtualization as an example. FIG. 3 is a diagram illustrating a functional configuration example of the single control device 11. Components having the same functions as those of the control device 1 in FIG. The single control device 11 includes an arithmetic processing unit 6a, a control information management unit 7, and a content management unit 8 instead of the virtual control devices 5-1 to 5-4 and the common processing unit 4 of the control device 1 of FIG. Yes. The control information management unit 7 and the content management unit 8 have the same functions as the control information management unit 7-i and the content management unit 8-i, respectively.

First, an example of a general transfer method in the Chord system will be described. In the Chord system, the control device that exists first in the clockwise direction from the ID of its own device in the ID space (ID circle) is called successor, and the control device that exists first in the reverse direction is called predecessor. Each control device uses the ID space larger than the predecessor ID and less than or equal to its own ID as the management area of the own control apparatus, and manages the content data having the ID in the management area. In addition, each control device has “own ID + 2 ⁱ⁻¹ (i = ^{1 to} m is a natural number, m is the number of bits of ID)” so that the transmitted data is efficiently transferred to the destination control device. Transfer information (generally called a finger table in the Chord system) to m control devices having IDs is held. When each control device receives destination ID data outside the management area, each control device selects a transfer destination having an ID smaller than the destination ID and closest to the destination from the finger table, and selects the selected transfer The received data is transferred first.

  For example, when the terminal wants to acquire content, the terminal transmits a content acquisition request including the ID of the content data (hereinafter referred to as content ID). Then, the acquisition request is sequentially transferred to the control device having an ID closer to the content ID based on the content ID, and finally transferred to the control device (final destination) that manages the content ID. The control device that manages the content ID transmits information such as the location of the content data to the transmission source terminal. In this way, the terminal can acquire content data.

  Next, the operation of the single control device 11 will be described. Also in the single control device 11, the control information management unit 7 holds transfer information, successor and predecessor information, as in the example of the general transfer method in the Chord system. Here, it is assumed that the content management unit 8 of the control device 11 holds the content in the management area of the own device.

  First, the single control device 11 is connected to an external network, and the reception processing unit 3 receives data via the external network. Then, the arithmetic processing unit 6a analyzes the received data and determines whether or not the destination ID is the ID of the management area of the own control device. When the ID is the management area of the own control device, the arithmetic processing unit 6a transfers the received data to the control information managing unit 7 for the control information and to the content managing unit 8 for the content acquisition request.

  If the received data is a content acquisition request, the content management unit 8 outputs the content data to the arithmetic processing unit 6a in accordance with the content acquisition request included in the received data transferred from the arithmetic processing unit 6a. The arithmetic processing unit 6a transmits the content data via the transmission processing unit 2 and the external network with the transmission source of the content acquisition request as the destination.

  If the received data is a control request, the control information management unit 7 reflects the content of the control request included in the received data transferred from the arithmetic processing unit 6a. For example, when related control devices are added, the transfer information is rewritten.

  On the other hand, if the arithmetic processing unit 6a determines that the destination ID is not the ID of the management area of the own control device, the processing unit 6a selects a transfer destination based on the destination ID of the received data, and receives the received data at the selected transfer destination. Transfer is performed via the transmission processing unit 2. The transfer method at this time is a general transfer method in the Chord system described above.

  Here, it is assumed that the content management unit 8 of the independent control device 11 holds the content in the management area of the own device, but the content management unit 8 stores the content data in another control device or the like. Only the location of content in the management area of the own device may be managed.

  Next, virtualization will be described. FIG. 4 is a diagram illustrating a functional configuration example in the case where one control device is physically operated as four virtual control devices. IDs in the Chord system are assigned to the virtual control devices 5-1 to 5-4. Each of the control devices 12 shown in FIG. 4 does not include the interface 9, but is otherwise the same as the control device 1 of FIG. 1. 4, components having the same functions as those in FIG. 1 are denoted by the same reference numerals.

  In the example of FIG. 4, one physical control device 12 is physically operated as four virtual control devices by virtualization, and different IDs are assigned to the virtual control devices 5-1 to 5-4, respectively. An example of operation in the case of such a configuration will be described. First, the reception processing unit 3 receives data, and the common processing unit 4 selects any one of the virtual control devices 5-1 to 5-4 to the selected virtual control devices 5-1 to 5-4. Transfer received data. When the destination ID value included in the received data at this time matches one of the ID values of the virtual control devices 5-1 to 5-4, the destination ID value is transferred to the virtual control device having the matching ID value.

  If the destination ID value does not match any of the ID values of the virtual control devices 5-1 to 5-4, for example, information for identifying the virtual control devices 5-1 to 5-4 other than the destination ID (for example, (IP address, port number, etc.) are included, the destination virtual control devices 5-1 to 5-4 are selected. Further, for example, the common processing unit 4 holds correspondence information between the destination ID and the destination virtual control device in advance, searches the correspondence information for the destination corresponding to the destination ID included in the received data, and transfers the information. You may make it select as a destination. However, the method of selecting the transfer destination virtual control devices 5-1 to 5-4 is not particularly limited, and a conventionally performed method may be used.

  Then, upon receiving the received data, the arithmetic processing unit 6-n (n = 1 to 4) to which the received data is transferred determines whether or not the destination ID is within the management area of the own device, and When not in the management area, each performs the same transfer processing as the arithmetic processing unit 6a of the single control device 11. Each of the control information management units 7-1 to 7-4 holds transfer information based on the ID of the own virtual device.

  If the arithmetic processing unit 6-n determines that the received data is within the management area of the own device, the received data is transferred to the content management unit 8-n when the received data is a content acquisition request, and the received data is a control request. Is transferred to the control information management unit 7-n. Then, the content management unit 8-n performs the same operation as the content management unit 8, and the control information management unit 7-n performs the same operation as the control information management unit 7. Then, the content data output from the content management unit 8-n is transmitted by the transmission processing unit 2 via the arithmetic processing unit 6-n and the common processing unit 4. That is, the virtual control devices 5-1 to 5-4 perform the same operation as that of the independent single control device 11 except for the transmission / reception operation.

  Next, transfer information held by the control information management units 7-1 to 7-4 of the control device 1 according to the present embodiment illustrated in FIG. 1 will be described. In the control device 12 of FIG. 4, although it is physically one control device, the transfer in the Chord system is performed completely independently. For example, it is assumed that the destination ID included in the received data transferred to the virtual control device 5-1 is the destination ID of the management area of the control device included in the transfer information held by the virtual control device 5-2. Then, it is assumed that the virtual control device 5-1 has no control information for managing the destination ID included in the received data in the transfer information held by the virtual control device 5-1. At this time, since the virtual control device 5-1 performs transfer to the device having the ID closest to the destination ID from the transfer information held by the own device, the virtual control device 5-1 finally transfers the destination ID to the device having the management area. Until it is done, at least one more transfer is required.

  On the other hand, assuming that the transfer information is shared among the virtual control devices 5-1 to 5-4, the virtual control device 5-1 converts the received data into the received data based on the transfer information held by the virtual control device 5-2. The included destination ID can be directly transferred to the device that manages the destination ID, and the number of transfers is one. As described above, the virtual control devices 5-1 to 5-4 can share the transfer information, thereby reducing the number of transfers. The transfer information held by the virtual control devices 5-1 to 5-4 is the ID assigned to the own device by the arithmetic processing units 6-1 to 6-4 or the control information management units 7-1 to 7-4, respectively. Assume that it is held after being calculated based on the value. In the present embodiment, the control information management units 7-1 to 7-4 share transfer information by referring to each other's transfer information via the interface 9.

  Hereinafter, the transfer information sharing method of this embodiment will be described in detail. As a method for sharing the transfer information, for example, there is a method in which the transfer information held by the virtual control devices 5-1 to 5-4 is referred to independently of each other. In this method, when there is overlapping information in the transfer information, the overlapping information is held in multiple. For this reason, in this embodiment, the transfer information is further reduced by deleting redundant information from the transfer information held by the control information management units 7-1 to 7-4. In this example, the overlapping portion of the transfer information is deleted, but it may be used as it is without being deleted.

  5A to 5C are diagrams illustrating a method for reducing transfer information. FIG. 5A is a diagram illustrating an example of the transfer information A-1 calculated by the virtual control device 5-1 based on the ID value assigned to the own device. 5A, the horizontal axis indicates the ID value (identification number), and here, the right side is the increasing direction of the numerical value of the ID value. In FIGS. 5A to 5C, the ID value of the virtual device 5-1 or the virtual device 5-2 is indicated by a black square and is included in the transfer information A-1 or the transfer information A-2. The transfer destination ID value is indicated by a white square. In the present embodiment, “ID value of virtual control device 5-1 <ID value of virtual control device 5-2 <ID value of virtual control device 5-3 <ID value of virtual control device 5-4”. .

  FIG. 5-2 is a diagram illustrating an example of transfer information A-1 held by the virtual control device 5-1, and transfer information A-2 held by the virtual control device 5-2. As shown in FIG. 5B, there may be an overlap section between the transfer information A-1 and the transfer information A-2. FIG. 5C is a diagram illustrating an example in which a portion overlapping with the transfer information A-2 is deleted from the transfer information A-1. FIG. 5C illustrates an example in which a transfer destination (here, the virtual control device 5-3) having an ID exceeding the ID of the virtual control device 5-2 is deleted from the transfer information A-1. .

  In the present embodiment, as illustrated in FIGS. 5A to 5C, the virtual control devices 5-1 to 5-4 are arranged in ascending order of IDs, and the virtual control devices 5-1 to 5-5 having the smallest IDs are arranged. -4, the transfer destination having an ID exceeding the IDs of the virtual control devices 5-1 to 5-4 having the second smallest ID is deleted. Similarly, from the transfer information of the virtual control devices 5-1 to 5-4 having the second smallest ID, transfer destinations having IDs exceeding the IDs of the virtual control devices 5-1 to 5-4 having the third smallest ID are selected. delete. Similarly, a transfer destination having an ID exceeding the ID of the virtual control device 5-1 to 5-4 having the largest ID from the transfer information of the virtual control device 5-1 to 5-4 having the third smallest ID. Is deleted.

  As described above, the virtual control devices 5-1 to 5-4 delete the transfer destination having an ID whose ID exceeds the ID of the virtual control device 5-1 to 5-4 having the next largest ID. , You can delete the duplicate part. For this reason, the capacity of the transfer information can be reduced. In addition, when searching for a transfer destination closest to the destination ID value in the transfer process described later using these transfer information, a duplicate search is unnecessary and the processing load can be reduced.

  Next, the operation of the present embodiment will be described. The operations of the transmission processing unit 2, the reception processing unit 3, and the common processing unit 4 are the same as those of the control device 12 shown in FIG. Here, a case will be described as an example where the virtual control device 5-1 has received reception data transferred from the common processing unit 4, but there are cases where reception data is transferred to the virtual control devices 5-2 to 5-4. The operations of the virtual control devices 5-2 to 5-4 are the same.

  When the arithmetic processing unit 6-1 of the virtual control device 5-1 receives the received data from the common processing unit 4, first, the destination ID value is larger than its own management area (predecessor ID value and less than its own ID). ) Or not. When it is determined that the destination ID value is the ID value of the management area of the own device, the content management unit 8-1 receives the received data as a content acquisition request, as in the control device 12, as a process in the own device. Data is transferred, and when the received data is a control request, it is transferred to the control information manager 7-1. The operations of the content management unit 8-1 and the control information management unit 7-1 are the same as the operations of the content management unit 8 and the control information management unit 7 of the control device 11, respectively.

  When the arithmetic processing unit 6-1 determines that the destination ID value is not the ID value of the management area of its own device, the following transfer process is performed. FIG. 6 is a flowchart illustrating an example of a transfer processing procedure according to the present embodiment. In the present embodiment, it is assumed that the control information management units 7-1 to 7-4 calculate and hold the transfer information from which the overlapping portions shown in FIG. 5 are deleted. The arithmetic processing units 6-1 to 6-4 use the ID values of all the virtual control devices 5-1 to 5-4 in the control device 1 as the identifiers of the virtual control devices 5-1 to 5-4, respectively. Assume that they are held in association. In the flowchart, a virtual control device is expressed as a virtual node, and when it is simply referred to as a node, it is a device having an independent ID without distinction between the control device and the virtual control device.

  First, the arithmetic processing unit 6-1 of the virtual control device 5-1 has the destination ID value of the received data transferred from the common processing unit 4 larger than the ID value of the predecessor and less than or equal to its own ID value (of its own device). It is determined whether it is a management area) (step S1). If it is the destination ID value in the management area of the own device (YES in step S1), the transfer process is terminated as it is because there is no need to transfer. If it is not the destination ID value of the management area of the own apparatus (step S1 NO), it is determined whether the destination ID value is equal to or less than the successor ID (step S2). As for the step S1, as described above, since the same processing is already performed in determining whether the transfer processing is already performed or the processing in the own device is performed, the step S1 is omitted and the processing starts from the step S2. You may do it.

  If it is determined that the destination ID is not less than or equal to the successor ID (NO in step S2), the arithmetic processing unit 6-1 further determines that the destination ID value is the next virtual node (within the same control device, the ID value is the own device). Next largest virtual node: In this example, it is determined whether it is less than the ID value of the virtual control device 5-2) (step S3). If it is determined that the destination ID value is not less than the ID value of the next virtual node (NO in step S3), the arithmetic processing unit 6-1 further selects a virtual node having a maximum ID value equal to or smaller than the destination ID value. (Step S4). Next, the arithmetic processing unit 6-1 refers to the transfer information held by the control information management unit 7-j of the selected virtual node (5-j, j = 2 to 4), and Among them, a transfer destination (node) having a maximum ID value less than or equal to the destination ID is selected (step S5). Then, the arithmetic processing unit 6-1 transfers the received data to the selected node via the common processing unit 4 and the transmission processing unit 2 (Step S6).

  On the other hand, if it is determined in step S2 that the destination ID value is equal to or less than the successor ID value (YES in step S2), the arithmetic processing unit 6-1 passes the common processing unit 4 and transmission processing unit 2 to the successor node. The received data is transferred (step S7).

  When it is determined in step S3 that the destination ID value is less than the ID value of the next virtual node (YES in step S3), the arithmetic processing unit 6-1 is held by the control information management unit 7-1. The transfer destination (node) having the maximum ID value below the destination ID is selected from among the transfer information (step S8), and the process proceeds to step S6.

  Steps S1 and S2 are the same as those in the ordinary Chord system, but in steps S3 to S5 of this embodiment, transfer information of another virtual control device in the same control device is referred to. For this reason, transfer can be performed to a node closer to the destination ID value, and the number of transfers required to reach the final destination node can be reduced. Here, the transfer processing procedure using the transfer information from which the duplicated part is deleted is shown. However, when the duplicated part is not deleted, the arithmetic processing unit 6- 6 is replaced with steps S3 to S5 and step S8. 1 may refer to the transfer information of all the virtual control devices in sequence, select a node having a maximum ID value less than or equal to the destination ID value, and proceed to step S6.

  In this embodiment, an example in which one physical control device 1 is operated as four virtual control devices 5-1 to 5-4 has been described. However, the present invention is not limited to this, and one physical control device. The transfer method of the present embodiment can be applied to any number of virtual control devices for one.

  Thus, in the present embodiment, the control information management units 7-1 to 7-4 of the virtual control devices 5-1 to 5-4 refer to each other's transfer information via the interface 9, and all The received data is transferred to a transfer destination having an ID value that is not more than the destination ID value and is closest to the destination ID value. Furthermore, the redundant part of the transfer information is deleted between the control information management units 7-1 to 7-4. For this reason, it is possible to transfer to a node closer to the destination ID value by one transfer, and it is possible to reduce the number of transfers required to reach the final destination node. Furthermore, the storage capacity and processing load can be reduced as compared with the case where the overlapping portion of the transfer information is not reduced.

Embodiment 2. FIG.
FIG. 7 is a diagram illustrating a functional configuration example of the control device according to the second embodiment of the present invention. As illustrated in FIG. 7, the control device 1a according to the present embodiment deletes the interface 9 from the control device 1 according to the first embodiment, and controls the control information management units 7-1 to 7-4 and the virtual control device 5-1. Are the same as the control device 1 of the first embodiment except that the control information management unit 7a and the virtual control devices 5a-1 to 5a-4 are provided instead of the control information management unit 7a. Components having the same functions as those of the first embodiment are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, the control device 1a includes a control information management unit 7a that centrally manages the control information of all the virtual control devices 5a-1 to 5a-4, and each arithmetic processing unit 6-1 to 6-6. 4, the information held by the control information management unit 7a can be referred to. The control information management unit 7a holds control information obtained by integrating the transfer information held by the control information management units 7-1 to 7-4 described in the first embodiment. Here, the transfer information to be held is obtained by deleting the overlapping portion as in the first embodiment. Furthermore, the control information management unit 7a centrally manages information (distribution information) necessary for packet distribution to communication terminals connected to the virtual control devices 5a-1 to 5a-4. The distribution information is, for example, information (communication distribution information) of communication terminals that distribute packets of the multicast group.

  Next, the transfer method according to this embodiment will be described. Operations other than the transfer method of the present embodiment are the same as those of the first embodiment. Hereinafter, a different part from Embodiment 1 is demonstrated.

  FIG. 8 is a flowchart illustrating an example of a transfer processing procedure according to the present embodiment. Step S11 and step S12 are the same as step S1 and step S2 of the first embodiment, respectively, and thus description thereof is omitted. In step S12, when it is determined in step S11 that the destination ID is not equal to or less than the successor ID (NO in step S12), the arithmetic processing unit 6-1 further transfers the transfer information held by the control information management unit 7a. , A transfer destination (node) having a maximum ID value that is equal to or smaller than the destination ID value is selected (step S13). Steps S14 and S15 are the same as steps S6 and S7 of the first embodiment, respectively, and thus description thereof is omitted. Thus, in this embodiment, it is only necessary to perform step S13 instead of steps S3, S4, S5, and S8 of the first embodiment, and the transfer processing procedure can be simplified as compared with the first embodiment.

  Next, sharing of multicast distribution information according to the present embodiment will be described. When multicast packet distribution using an overlay network is performed, a plurality of virtual control apparatuses belonging to the same control apparatus may receive distribution of the same multicast packet. In this case, multicast packets are duplicated and transmitted to the same control device, and traffic is wasted. In the present embodiment, multicast distribution information is shared in order to avoid this duplicate reception.

  FIG. 9 is a diagram illustrating a method of avoiding double packet distribution by sharing multicast distribution information. FIG. 10 is a diagram illustrating an example of distribution information. FIG. 10 shows distribution information related to the virtual control device 5a-1. Such distribution information is held for all of the virtual control devices 5a-1 to 5a-4. First, it is assumed that the communication terminal 10a-1 is connected to the virtual control device 5a-1 and receives packet distribution of the multicast group x. The upper part of FIG. 10 shows distribution information of the virtual control device 5a-1 in this state. In this way, the distribution information of the virtual control device 5a-1 stores the communication terminals receiving the distribution for each multicast group.

  Next, the communication terminal 10a-2 connected to the virtual control device 5a-2 transmits a distribution request for the multicast group x. When the arithmetic processing unit 6-2 of the virtual control device 5a-2 receives the multicast group distribution request via the reception processing unit 3 and the common processing unit 4, the arithmetic processing unit 6-2 refers to the distribution information held by the control information management unit 7a. Thus, the virtual control devices 5a-1 to 5a-4 including distribution information to the multicast group x are searched.

  In this case, the arithmetic processing unit 6-2 obtains the virtual control device 5a-1 as a result of searching for the virtual control devices 5a-1 to 5a-4 including the distribution information to the multicast group x. Then, the arithmetic processing unit 6-2 adds the communication terminal 10a-2 to the distribution information of the virtual control device 5a-1. The lower part of FIG. 10 shows distribution information (a row corresponding to multicast x) of the virtual control device 5a-1 with the communication terminal 10a-2 added.

  FIG. 11 is a flowchart illustrating an example of a multicast distribution setting process procedure according to the present embodiment. Hereinafter, similarly to FIG. 9, a case where the virtual control device 5a-2 receives a multicast group distribution request from the communication terminal 10a-2 connected to the own device will be described. First, the arithmetic processing unit 6-2 of the virtual control device 5a-2 searches the distribution information of the virtual control device 5a-1 held by the control information management unit 7a, and is the same as the multicast group that requested the distribution. It is determined whether there is a multicast group entry (information) (step S21). If it is determined that there is an entry for the same multicast group (YES in step S21), the communication terminal 10a-2 is added to the distribution information of the virtual control device 5a-1 (step S22), and the multicast distribution setting process is terminated. .

  On the other hand, when it is determined in step S21 that there is no entry of the same multicast group (NO in step S21), the arithmetic processing unit 6-2 determines that all the virtual nodes (here, the virtual control devices 5a-1 to 5a-4). ) Is determined (step S23). If it is determined that not all virtual nodes have been searched (NO in step S23), one of the unsearched virtual nodes is selected (step S24), and the processes in and after step S21 are repeated.

  If it is determined in step S23 that all virtual nodes have been searched (YES in step S23), the arithmetic processing unit 6-2 performs a common process on a multicast packet distribution request for joining the multicast group. The multi-packet distribution request is transmitted to the transmission destination of the multi-packet distribution request (a device that manages the multi-packet request, another control device that receives multi-packet distribution, etc.) via the unit 4 and the transmission processing unit 2 (step S25). Then, the communication terminal 10a-2 is added to the distribution information of the multi-packet group of the own device (5a-2) (step S22).

  In the present embodiment, the control information management unit 7a manages the distribution information in a unified manner, but the control information management units 7-1 to 7-4 have the same configuration as the control device 1 of the first embodiment. The steps shown in FIG. 11 may be performed by referring to each other. In this case, the arithmetic processing unit 6-2 searches all the virtual nodes by sequentially referring to the distribution information of the control information management unit 7-1 instead of referring to the distribution information of the control information management unit 7a. do it.

  In this embodiment, the distribution information is held for each virtual control device. However, the distribution information is integrated, and the distribution information of all the virtual control devices 5a-1 to 5a-4 is set as one distribution information. You may make it manage. FIG. 12 is a flowchart illustrating an example of a multicast distribution setting process procedure when the distribution information is integrated as described above.

  The process in this case will be described with reference to FIG. First, the virtual control device 5a-2 searches the integrated distribution information held by the control information management unit 7a, and determines whether there is an entry for the same multicast group as the multicast group that requested the distribution. (Step S31).

  If there is an entry for the same multicast group (YES in step S31), the communication terminal 6-2 is added to the integrated distribution information (step S32). If there is no entry for the same multicast group (NO in step S31), a multicast packet distribution request for participating in the multicast group is sent to the destination of the multi-packet distribution request via the common processing unit 4 and the transmission processing unit 2 (multi-packet). The request is transmitted to a device that manages the request, another control device that receives multi-packet distribution, or the like (step S33). Then, the communication terminal 10a-2 is added to the distribution information of the multi-packet group of the own device (5a-2) (step S32). Thus, when the integrated distribution information is used, the processing procedure can be simplified as compared with the case of FIG.

  As described above, in this embodiment, the control information management unit 7a manages the transfer information and the control information in an integrated manner. For this reason, the transfer process can be simplified as compared with the first embodiment, and the duplicate distribution of the same multicast group can be avoided. Further, by integrating the distribution information, it is possible to simplify the multicast group distribution setting process.

  As described above, the packet transfer method and control device according to the present invention are useful for packet transfer in an overlay network, and are particularly suitable for packet transfer in a Chord system including a virtual node.

It is a figure which shows the function structural example of Embodiment 1 of the control apparatus concerning this invention. 2 is a diagram illustrating an example of an overlay network according to Embodiment 1. FIG. It is a figure which shows the function structural example of a single control apparatus. It is a figure which shows the function structural example in the case of operating one control apparatus physically as four virtual control apparatuses. It is a figure which shows the transfer information of the virtual control apparatus 5-1. It is a figure which shows an example of the transfer information which the virtual control apparatus 5-1 hold | maintains, and the transfer information which the virtual control apparatus 5-2 hold | maintains. It is a figure which shows the transfer information which deleted the duplication part. 3 is a flowchart illustrating an example of a transfer procedure according to the first embodiment. It is a figure which shows the function structural example of Embodiment 2 of the control apparatus concerning this invention. 10 is a flowchart illustrating an example of a transfer processing procedure according to the second embodiment. It is a figure which shows the method of avoiding double delivery of a packet by sharing multicast delivery information. It is a figure which shows an example of the delivery information of virtual control apparatus 5a-1. 10 is a flowchart illustrating an example of a multicast distribution setting process procedure according to the second embodiment. It is a flowchart which shows an example of the multicast delivery setting processing procedure at the time of integrating delivery information.

Explanation of symbols

1, 1a, 12 Controller 2 Transmission processor 3 Reception processor 4 Common processor 5-1 to 5-4, 5a-1 to 5a-4 Virtual controller 6-1 to 6-4, 6a Arithmetic processor 7 , 7-1 to 7-4, 7a Control information management unit 8, 8-1 to 8-4 Content management unit 9 Interface 10-1 to 10-5, 10a-1, 10a-2 Communication terminal 11 Single control device

Claims (11)

In a communication system comprising an overlay network including a control device including a plurality of virtual control devices, a unique identification number is assigned and a management area in an identification number space is individually assigned based on the identification number, and identification in the management area A packet transfer method in a virtual control device that manages content having a number ,
On the basis of the identification number to generate the identification number of the predetermined number, the apparatus having a generated identification number to generate a transfer information and a transfer destination, the transfer information, all the virtual controller belonging to the same control device A transfer information generation step that can be shared between them,
The virtual control device that has received the data among all the virtual control devices, when the destination identification number indicating the final destination included in the received data is not the management area of the own device, based on the destination identification number, A transfer destination selection step for selecting a transfer destination from transfer information held in a sharable manner;
A transfer step of virtual controller which has received the reception data transfers the received data to a transfer destination and the selected,
A packet transfer method comprising:   2. The packet transfer method according to claim 1, wherein, in the transfer information generation step, each virtual control device generates the transfer information based on unique identification information.   In the transfer information generation step, transfer information of a transfer destination having an identification number less than the identification number of the virtual control device having the next largest identification number among the virtual control devices belonging to the same control device is generated. The packet transfer method according to claim 2.   In the transfer destination selection step, when the destination identification number is less than the identification number of the virtual control device having the next largest identification number, a transfer destination is selected based on the transfer information of the own device, while the destination If the identification number is equal to or greater than the identification number of the virtual control device having the next largest identification number, the virtual control device having the largest identification number not more than the destination identification number among the virtual control devices belonging to the same control device 4. The packet transfer method according to claim 3, wherein a transfer destination is selected based on the transfer information.   The packet transfer method according to claim 1, wherein in the transfer information generation step, one transfer information is generated by integrating a list of transfer destinations generated for each virtual control device.   The transfer destination selecting step selects a transfer destination having a maximum identification number equal to or less than the destination identification number from the transfer information. Packet transfer method. When there is a multicast group distribution request from a terminal connected to the virtual control apparatus, distribution information stored in all the virtual control apparatuses and stored in the subordinate terminals receiving the multicast group distribution is stored. A distribution setting processing step of searching and adding the terminal to the obtained distribution information when the distribution information of the same multicast group as the multicast group requested for distribution is obtained as a search result;
The packet transfer method according to claim 1, further comprising: The distribution information is held for each virtual control device,
The packet transfer method according to claim 7, wherein in the distribution setting processing step, distribution information is searched for each virtual control device.   8. The packet transfer method according to claim 7, wherein distribution information of all the virtual control devices is integrated and held as one distribution information. A control device comprising a plurality of virtual control devices that configure an overlay network and that manage content having an identification number in the management area, each of which is assigned a management area in an identification number space based on a unique identification number,
Each of the virtual control devices
On the basis of the identification number to generate the identification number of the predetermined number, the apparatus having a generated identification number to generate a transfer information and a transfer destination, the transfer information, all the virtual controller belonging to the same control device Control information management means to be held sharable between,
When the destination identification number indicating the final destination included in the received data is not in the management area of its own device, based on the destination identification number, the transfer destination is selected from the transfer information held in a sharable manner and transferred. Computing means for
A control device comprising: A control device comprising a plurality of virtual control devices that configure an overlay network and that manage content having an identification number in the management area, each of which is assigned a management area in an identification number space based on a unique identification number,
Control information management means for integrating and holding transfer information for each virtual control device, with transfer devices having a predetermined number of identification numbers generated based on the identification number as transfer destinations ,
With
The virtual control device is
When the destination identification number indicating the final destination included in the received data is not in the management area of its own device, based on the destination identification number, the transfer destination is selected from the transfer information held in a sharable manner and transferred. Computing means for
A control device comprising:

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