Information-centric networking system, publisher node, router, system control method and system control program

Abstract

An information-centric networking (ICN) system (100) which comprises a plurality of routers (20), a publisher node (10) that delivers a content and a subscriber node (30) that requests the content. Th

Description

INFORMATION-CENTRIC NETWORKING SYSTEM, PUBLISHER NODE, ROUTER, SYSTEM CONTROL METHOD AND SYSTEM CONTROL PROGRAM FIELD

[0001] <Cross-reference to related application> The present invention is based on the priority of Japanese patent application No. 2024-093968 (filed on June 10, 2024), the entire contents of the same application are incorporated by reference in the present application. The present invention relates to an informationcentric networking system, a publisher node, a router, a system control method and a system control program. BACKGROUND

[0002] A technology referred to Information-centric networking (ICN) has been researched (see, for example, Patent Literature (PTL) 1). Under the information-centric networking, a router stores a content delivered from a publisher node in its cache and delivers the content based on its content name. Therefore, a subscriber node only needs to access to any one of routers that store the content, resulting in distribution of access to the publisher node.

[0003] PTL 1: Tokkai JP 2019-091375A SUMMARY

[0004] The following analysis is made from an aspect of the present invention. Herein, disclosure of the document cited above is incorporated in the present application by reference thereto.

[0005] As described above, under the information-centric networking, since access to the publisher node is distributed, a mobile node vulnerable to access concentration may be utilized as the publisher node. However, when the publisher node makes a positional shift, a problem will arise that the subscriber node would not be possible to access to the publisher node under a routing based on the content name.

[0006] Concretely, under a state where any one of routers stores the content, it is sufficient for the subscriber node to have a mechanism for accessing such router, thus accessing the publisher node is not essential. Therefore, the publisher node is disparaged as an access destination, and thus the positional shift of the publisher node is not followed up.

[0007] However, since the routers store the content on their cache, the content would be deleted from all of the routers on a certain time point. In addition, since the routers store the content on their cache when it relays the content, under a state where the content has not been delivered from the publisher node even once, all of the routers never store the content. Under such situation, although required is accessing the publisher node, the positional shift of the publisher node provides a problem that the routing based on the content name cannot realize accessing the publisher node.

[0008] In other words, a conventional information-centric networking involves a problem that the positional shift of the publisher node makes content distribution unavailable.

[0009] Accordingly, it is a purpose of the present invention to provide an information-centric networking system, a publisher node, a router, a system control method and a system control program that contribute to a reliable content delivery.

[0010] According to a first aspect of the present invention, there is provided an information-centric networking system, comprising: a plurality of routers that configure an information-centric network, a publisher node that delivers a content, and a subscriber node that requests the content, wherein, the publisher node comprises: a router detection part that detects a router in the closest connection relationship among the plurality of routers, a notification part that performs a notification for announcing that the publisher node stores the content to a first router in the closest connection relationship, and a re-notification part, when it is detected that own positional shift resulted in a replacement of the router in the closest connection relationship, performs a re-notification for announcing that the publisher node stores the content to a second router which newly becomes in the closest connection relationship, and each of the plurality of routers comprises: a notification processing part that, when receiving the notification, forwards the notification to the other router(s) in a connection relationship, and registers in a memory the publisher node or router, which is a source forwarder of the notification, as a forwarding destination of a content request derived from the subscriber node, and a re-notification processing part that, when receiving the re-notification, forwards the re-notification to the other router(s) in a connection relationship, and updates the forwarding destination of the content request to the publisher node or router, which is a source forwarder of the re-notification.

[0011] According to a second aspect of the present invention, there is provided a publisher node, comprising: a router detection part that detects a router in the closest connection relationship among a plurality of routers, a notification part that performs a notification for announcing that the publisher node stores a content to a first router in the closest connection relationship, and a re-notification part, when it is detected that own positional shift resulted in a replacement of the router in the closest connection relationship, performs a re-notification for announcing that the publisher node stores the content to a second router which newly becomes in the closest connection relationship.

[0012] According to a third aspect of the present invention, there is provided a router, comprising: a notification processing part that, when receiving a notification for content storage, forwards the notification to the other router(s) in a connection relationship, and registers in a memory a publisher node or router, which is a source forwarder of the notification, as a forwarding destination of a content request derived from a subscriber node, and a re-notification processing part that, when receiving a re-notification for content storage, forwards the re-notification to the other router(s) in a connection relationship, and updates the forwarding destination of the content request to the publisher node or router, which is a source forwarder of the re-notification.

[0013] According to a fourth aspect of the present invention, there is provided a system control method, wherein an information-centric networking system comprises: a plurality of routers that configure an information-centric network, a publisher node that delivers a content, and a subscriber node that requests the content, the publisher node executes: detecting a router in the closest connection relationship among the plurality of routers, performing a notification for announcing that the publisher node stores the content to a first router in the closest connection relationship, and when it is detected that own positional shift resulted in a replacement of the router in the closest connection relationship, performing a renotification for announcing that the publisher node stores the content to a second router which newly becomes in the closest connection relationship, and each of the plurality of routers executes: when receiving the notification, forwarding the notification to the other router(s) in a connection relationship and registering in a memory the publisher node or router, which is a source forwarder of the notification, as a forwarding destination of a content request derived from the subscriber node, and when receiving the re-notification, forwarding the re-notification to the other router(s) in a connection relationship and updating the forwarding destination of the content request to the publisher node or router, which is a source forwarder of the re-notification.

[0014] According to a fifth aspect of the present invention, there is provided a system control program, wherein an information-centric networking system comprises: a plurality of routers that configure an information-centric network, a publisher node that delivers a content, and a subscriber node that requests the content, the publisher node is caused to execute: detecting a router in the closest connection relationship among the plurality of routers, performing a notification for announcing that the publisher node stores the content to a first router in the closest connection relationship, and when it is detected that own positional shift resulted in a replacement of the router in the closest connection relationship, performing a renotification for announcing that the publisher node stores the content to a second router which newly becomes in the closest connection relationship, and each of the plurality of routers is caused to execute: when receiving the notification, forwarding the notification to the other router(s) in a connection relationship and registering in a memory the publisher node or router, which is a source forwarder of the notification, as a forwarding destination of a content request derived from the subscriber node, and when receiving the re-notification, forwarding the re-notification to the other router(s) in a connection relationship and updating the forwarding destination of the content request to the publisher node or router, which is a source forwarder of the re-notification.

[0015] According to each aspect of the present invention, there are provided an information-centric networking system, a publisher node, a router, a system control method and a system control program that contributes to a reliable content delivery. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is an explanatory view of one outline. Figure 2 is a diagram showing an example of a router. Figure 3 is a diagram showing an example of a publisher node. Figure 4 is an explanatory view of a notification process. Figure 5 is an explanatory view of a re-notification process. Figure 6 is a diagram showing an example of flow of processes by the publisher node. Figure 7 is a diagram showing an example of flow of processes by a node. Figure 8 is an explanatory view of content delivery under a situation where the publisher node has not made positional shift. Figure 9 is an explanatory view of content delivery after the positional shift of the publisher node. Figure 10 is a diagram showing a conventional technology. Figure 11 is an explanatory view of the notification process. Figure 12 is an explanatory view of the re-notification process. Figure 13 is a diagram showing an example of a computer as the publisher node. Figure 14 is a diagram showing an example of a computer as the router. EXAMPLE EMBODIMENTS

[0017] A preferable example embodiment which may be realized by the present invention is explained in detail with reference to the drawings. Herein, reference signs in the following description are expediently attached to each element as an explanatory aid for understanding, but not for limitation of the present invention to an illustrated configuration. In addition, connection lines between blocks in each figure include both of bidirectional and one directional. One way arrow schematically indicates a flow of main signal (data), thus does not exclude bidirectional. In addition, in a circuit diagram, a block diagram, an inner configuration diagram, a connection diagram, etc., illustrated in the present disclosure, input / output ends of each of connection lines respectively have input / output ports, but explicit indications thereof are omitted. The same is applied to input / output interfaces, too.

[0018] One outline of the present invention is explained. As illustrated in Figure 1, an information-centric networking system 100 comprises a publisher node 10 that distributes a content, a plurality of routers 20 that configures an information-centric network, and a subscriber node 30 that requests the content.

[0019] A publisher node 10 comprises a router detection part 11, a notification part 12 and a re-notification part 13. The router detection part 11 detects a router in the closest connection relationship among the plurality of routers 20. The notification part 12 performs a notification for announcing that the publisher node stores the content to a first router in the closest connection relationship. A re-notification part 13, when it is detected that own positional shift resulted in a replacement of the router in the closest connection relationship, performs a re-notification for announcing that the publisher node stores the content to a second router which newly has become in the closest connection relationship.

[0020] Each of the router 20 comprises a notification processing part 21 and a re-notification processing part 22. The notification processing part 21, when receiving the notification, forwards the notification to the other router(s) in a connection relationship, and registers in a memory the publisher node 10 or router 20, which is a source forwarder of the notification, as a forwarding destination of a content request derived from the subscriber node 30. The re-notification processing part 22, when receiving the re-notification, forwards the re-notification to the other router(s) in a connection relationship, and updates the forwarding destination of the content request to the publisher node 10 or router 20, which is a source forwarder of the re-notification.

[0021] Herein, the "router 20" indicates a general term of each router, and comprises "first router", "second router", "the other routers" and the like. Their reference signs are arbitrarily omitted to prevent confusion.

[0022] According to the above information-centric networking system 100, even if the publisher node 10 makes a positional shift, the renotification would be performed for announcing that the publisher node stores the content at a location after the positional shift, thus there is no problem that the subscriber node 30 cannot access the publisher node 10.

[0023] [Example embodiment 1] The information-centric networking system 100 will be explained below using a concrete example.

[0024] Similar to the above outline, the information-centric networking system 100 comprises the publisher node 10, the plurality of routers 20 and the subscriber node 30.

[0025] As shown in Figure 2, each router 20 comprises a notification processing part 21, a re-notification processing part 22 and a memory, and also comprises general components (such as a port, not shown) for functioning as the router 20. The memory includes two tables referred to as FIB (Forwarding Information Base) and PIT (Pending Interest Table). Herein, in a case where the routers are distinguished from one another, it is referred to as "Router A" and the like, and its reference sign is arbitrarily omitted. In addition, reference signs of "the other (another) router(s)", "router in the closest connection relationship (the closest router)" are also arbitrarily omitted for preventing confusion.

[0026] FIB is a table in which a content name (Name) and a forwarding destination of a content request derived from the subscriber node 30 (Next) is associated. For example, with respect to Router B of Figure 4, it is indicated that a content request of content name: data-P is forwarded to Router C. As a whole, a routing (relaying, forwarding) of the content request is performed such that, based on the content name: data-P, the subscriber node 30->Router A->Router B->Router C->the publisher node 1 0.

[0027] PIT is a table relating to unprocessed content request, in which registered are a content name which is described on a content request (Name) and a node which had received the content request (Requested) [the node was received and forwarded the content request to it, thus registered as a node who (Requested) the content]. For example, with respect to Router B of Figure 8, it is indicated that a content request relating to a content name: data-P has been received from Router A, but this content request is not processed yet (unprocessed). Herein, when Router B receives the data itself of the content (data-P), Router B makes reference to PIT and forwards the received content (data-P) to Router A. Entirely, a content delivery is performed such that, based on a content name: data-P, the publisher node 10->Router C->Router B->Router A->the subscriber node 30.

[0028] The notification processing part 21 performs forwarding a notification and information registration on FIB. For example, Router B of Figure 4 receives a notification for announcing that the publisher node 10 stores content name: data-P from Router C. [Thus, Router C is referred to as "source forwarder" of the notification]. At that time, Router B forwards the notification to Router A and Router E. In addition, Router B registers the content name: data-P on Name of FIB and registers Router C on Next. By virtue of such processes, FIB of Router B becomes as that shown in Figure 4.

[0029] The re-notification processing part 22 performs forwarding a re notification and update of FIB. For example, assumed is a situation where, starting from a situation of Figure 4, the publisher node 10 has made a positional shift, resulting in a situation of Figure 5. At that time, for example, Router B of Figure 4 receives a re-notification for announcing that the publisher node 10 store content name: data-P from Router E. [Thus, Router E is referred to as "source forwarder" of the renotification.] At that time, Router B forwards the re-notification to Router A and Router C. In addition, Router B updates Next about content name: data-P on FIB to Router E. By virtue of such processes, FIB of Router B is updated to that shown in Figure 5.

[0030] In Figure 5, with respect a content request derived from the subscriber node 30, a routing is performed such that, based on content name: data-P, the subscriber node 30->Router A->Router B->Router E->the publisher node 10. In addition, with respect a content, a delivery is performed such that, based on content name: data-P, the publisher node 10->Router E->Router B->Router A->the subscriber node 30.

[0031] The publisher node 10 is exemplified by, for example, a smartphone. Concretely, as shown in Figure 3, the publisher node 10 comprises a router detection part 11, a notification part 12, a re-notification part 13 and a memory, and also comprises general components (communication function and the like, not shown) for functioning as the publisher node 10. Herein, the present application has a premise that the publisher node 10 makes positional shift, thus it is thought that the publisher node 10 and the router 20 are in a radio connection, but a cable connection may be also applicable.

[0032] In Figure 4, the router detection part 11 detects Router C as a router in the closest connection relationship. In addition, in Figure 5, the router detection part 11 detects Router E as a router in the closest connection relationship. Hereinafter, the router in the closest connection relationship is referred to as "the closest router".

[0033] With respect to detection of the closest router, various existing technologies are applicable. For example, an existing smartphone has a function automatically detecting an optimal access point and switching thereto. Such optimal access point may be regarded as the closest router. In addition, the router detection part 11 may periodically make an inquiry to the routers 20 in connection. Herein, a router 20 provided a reply to the inquiry in first may be said as the closest router. When a router 20 provided the reply is different from that provided a former reply, the router detection part 11 may determine that the router in the closest connection relationship has been replaced.

[0034] The notification part 12 performs a notification for announcing that the publisher node stores the content to a first router in the closest connection relationship. Figure 4 indicates a situation where the notification part 12 has performed a notification relating to content storage of content: data-P to Router C as the "first router". Herein, it is considered that, as a trigger of the notification by the notification part 12, for example, storing of the content or a delivery instruction by a content delivery agent.

[0035] The re-notification part 13 performs a re-notification for announcing that the publisher node stores the content to a second router which has newly become in the closest connection relationship. Figure 5 indicates a situation where the re-notification part 13 has performed a renotification relating to content storage of content: data-P to Router E as the "second router". By virtue of the re-notification, FIB of Routers B, C, E is updated.

[0036] The subscriber node 30 is a node that obtains the content, and is exemplified by, for example, a smartphone.

[0037] An example of flow of processes by the publisher node 10 and the routers 20 is explained below.

[0038] As illustrated in Figure 6, when a content is stored (Step Sil, Yes), the publisher node 10 detects a router in the closest connection relationship 20 (Step S12). Then, the publisher node 10 performs a notification for announcing that the publisher node 10 stores the content to the detected closest router (first router) (Step S13). After that, the publisher node 10 periodically performs detection of the closest router (Step S14, No). Herein, when the publisher node 10 detects that own positional shift results in replacement of the closest router (Step S14, Yes), the publisher node 10 performs a re-notification for announcing that the publisher node 10 stores the content to a second router which newly becomes in the closest connection relationship (Step S15).

[0039] As illustrated in Figure 7, when the notification is received (Step S21, Yes), the router 20 performs information registration on FIB (Step S22). After that, when the re-notification is received (Step S23, Yes), the router 20 updates information on FIB (Step S24).

[0040] Herein, processes of content delivery, and the like, are similar to that of conventional one.

[0041] A difference between the present invention and a conventional technology is explained below. In first, as a common matter in both of the present invention and conventional technology, a notification is performed with a trigger of storing a content in the publisher node 10, resulting in a situation of Figure 4. Under such situation, when a content name: data-P is requested from the subscriber node 30, routing of the content request is performed such that the subscriber node 30->Router A->Router B->Router C->the publisher node 10, thus the content request reaches the publisher node 10. Herein, PIT of each router 20 has a state of Figure 8 at that time.

[0042] Under a situation of Figure 4, it is assumed that the publisher node 10 made a positional shift. At that time, in the present invention, FIB of the routers 20 has been updated by virtue of the re-notification from the publisher node 10 as shown in Figure 5. Therefore, when the subscriber node 30 requests content name: data-P, PITs of the routers 20 become those indicated in Figure 9. That is, routing of the content request from the subscriber node 30 is performed such that the subscriber node 30->Router A->Router B->Router E->the publisher node 10, thus the content request reaches the publisher node 10.

[0043] On the other hand, in a conventional technology, FIBs of the routers 20 are still being those of Figure 4 even after the positional shift of the publisher node 10. Therefore, as shown in Figure 10, routing of the content request is performed such that the subscriber node 30->Router A->Router B->Router C. Router C would cause a forwarding failure for the content request, since the publisher node 10, which is the forwarding destination of the content request, is already not existing there.

[0044] It can be said that such transmission failure for the content request in the conventional technology indicates that the publisher node 10 is disparaged as an access destination and the positional shift of the publisher node is not followed up. In other words, it can be also said that, in the conventional technology, the publisher node 10 is assumed to be a fixed apparatus like a server, etc., and thus the positional shift of the publisher node 10 is out of consideration.

[0045] [Variational mode] The updating of FIB based on the re-notification may be addition of information. For example, when receiving a re-notification, although Router B updates Next of FIB from "Router C" to "Router E", Router B may add "Router E" thereto.

[0046] [Example embodiment 2] In the information-centric networking, the content name may have a layered-name structure which includes an internet domain name. Herein, when the publisher node 10 makes a positional shift, change of the domain name is sometime required.

[0047] For example, content data-P of AAA-company sometime may have a content name of AAA.com / data-P. Herein, it is assumed that the publisher node 10 performs a notification via Router Cl arranged in the AAA-company. In addition, it is also assumed that the publisher node 10 makes a positional shift and then performs a re-notification via Router C2 which is arranged in the AAA-company likewise Router Cl. Under such situation, A A A. com / data-P is no problem, since that means a content delivered from inside of the AAA-company.

[0048] However, if the re-notification is performed via Router E arranged outside of the AAA-company, since the content would not be a content delivered from inside of the AAA-company, it would be required to change the domain name AAA.com / . However, changing the content name is problematic in terms of universal recognition of the content name.

[0049] Therefore, the router detection part 11 periodically makes an inquiry to the router in the closest connection relationship about its belonging network. In addition, the re-notification part 13, when a reply to the inquiry from the router in the closest connection relationship is different from a former reply, determines that own positional shift results in a replacement of the router 20 in the closest connection relationship, and also results in a shift of own belonging network. Then, the re-notification part 13 performs a re-notification for announcing that the publisher node stores the content to a second router which newly becomes in the closest connection relationship. Particularly, the notification part 12 performs a notification for announcing a content name, and the re-notification part 13 preforms a re-notification for announcing a different content name and also announcing that the different content name indicates the same content as that indicated by the content name having been notified by the notification part.

[0050] A concrete example is explained. As illustrated in Figure 11, a network to which Routers Cl to C3 belong is regarded as a local area network of AAA-company. It is assumed that the publisher node 10 has performed a notification for announcing content name: AAA. com / data-P when its closest router is Router Cl. At that time, FIBs of Router A and the like have a state indicated in Figure 11. In addition, the publisher node 10 makes an inquiry about its belonging network to Router Cl, and then obtains a reply from Router Cl, that Router Cl belongs to the local area network of AAA-company.

[0051] Starting from the situation of Figure 11, it is assumed that the publisher node 10 makes a positional shift, resulting in that its closest router is Router E. At that time, the publisher node 10 makes an inquiry to Router E about its belonging network, and then obtains a reply that Router E belongs to a public network. Herein, since the reply from Router E is different from the reply from Router Cl, the publisher node 10 determines that own positional shift results in a replacement of the closest router and also results in a shift of own belonging network. Then, the publisher node 10 performs announcement of content name: BBB. com / data-P to Router E. At that time, the publisher node 10 performs a re-notification for announcing that content name: BBB.com / data-P is the same content as content name: AAA.com / data-P.

[0052] At that time, FIBs of the routers 20 have a state indicated in Figure 12. For example, on Name of FIB of Router B, registered is content name: AAA.com / data-P and additional content name: (BBB.com / data-P), which indicates that it is the same content. In addition, on Next of FIB of Router B, Router E is additionally registered. Under such state, when receiving a request for content name: A A A. com / data-P, Router B regards AAA. com / data-P = (BBB. com / data-P), thus forwards the content request to both of Router Cl and Router E.

[0053] Conclusively, even after the positional shift of the positional shift and the re-notification for content name: BBB .com / data-P, the content request reaches from the subscriber node 30 to the publisher node 10 based on content name: AAA.com / data-P. Therefore, a problem that the subscriber node 30 cannot access the publisher node 10 is solved.

[0054] [Example embodiment 3] It is assumed that the publisher node 10 performed a notification of content name: AAA.com / data-P via Router Cl, then made a positional shift, and then performed a re-notification via Router C2. At that time, it is sufficient that Routers Cl to C3 within a local area network of AAA-company receives re-notification and updates FIBs. In other words, since FIBs of Routers A, B, D, E would not be modified even if Routers A, B, D, E receive the re-notification, it is not required to forward the re-notification to Routers A, B, D, E. Therefore, it is considered to hold the re-notification on Routers Cl to C3.

[0055] That is, the re-notification part 13 detects that, even though a reply to the inquiry from Router C2 about its belonging network is the same as the former one from Router Cl, own (publisher node 10) positional shift results in a shift into the closest router. At that time, the re-notification part 13 performs a re-notification announcing that the publisher node 10 stores the content to Routers Cl to C3 which belong to the same belonging network as Router C2 which has become the closest router.

[0056] For example, it is considered that the routers 20 belonging to the local area network of AAA-company is designated as destinations of the renotification. As illustrated in Figure 11, although the local area network of AAA-company is connected to a public network via Router Cl, Router Cl may terminate forwarding the re-notification to Router B.

[0057] Since the forwarding area of the re-notification is limited, network load is reduced.

[0058] Furthermore, the present invention may be realized as a program that causes a computer to execute processes. For example, a computer as the publisher node 10 comprises a memory, CPU (Central Processing Unit) and an interface as illustrated in Figure 13. CPU reads out a program of the present invention from the memory to realize a processing module corresponding to the router detection part 11, the notification part 12 and the re-notification part 13.

[0059] Furthermore, a computer as the router 20 realizes a processing module corresponding to the notification processing part 21 and the renotification processing part 22 as illustrated in Figure 14. Herein, the memory stores FIB and PIT.

[0060] A part or entire of the example embodiment(s) may be described as the following modes, but not limited thereto.

[0061] (Mode 1) An information-centric networking system, comprising: a plurality of routers that configure an information-centric network, a publisher node that delivers a content, and a subscriber node that requests the content, wherein, the publisher node comprises: a router detection part that detects a router in the closest connection relationship among the plurality of routers, a notification part that performs a notification for announcing that the publisher node stores the content to a first router in the closest connection relationship, and a re-notification part, when it is detected that own positional shift resulted in a replacement of the router in the closest connection relationship, performs a re-notification for announcing that the publisher node stores the content to a second router which newly becomes in the closest connection relationship, and each of the plurality of routers comprises: a notification processing part that, when receiving the notification, forwards the notification to the other router(s) in a connection relationship, and registers in a memory the publisher node or router, which is a source forwarder of the notification, as a forwarding destination of a content request derived from the subscriber node, and a re-notification processing part that, when receiving the re-notification, forwards the re-notification to the other router(s) in a connection relationship, and updates the forwarding destination of the content request to the publisher node or router, which is a source forwarder of the re-notification.

[0062] (Mode 2) The information-centric networking system according to Mode 1, wherein the router detection part periodically makes an inquiry to the router in the closest connection relationship about its belonging network, and the re-notification part, when a reply to the inquiry from the router in the closest connection relationship is different from a former reply, determines that own positional shift resulted in a replacement of the router in the closest connection relation and also resulted in a shift of own belonging network, and performs the re-notification for announcing that the publisher node stores the content to the second router which newly becomes in the closest connection relationship.

[0063] (Mode 3) The information-centric networking system according to Mode 2, wherein the notification part performs the notification for announcing a content name, the re-notification part preforms the re-notification for announcing a different content name and also announcing that the different content name indicates the same content as that indicated by the content name having been notified by the notification part.

[0064] (Mode 4) The information-centric networking system according to Mode 3, wherein the re-notification part, when it is detected that own positional shift results in a replacement of the router in the closest connection relationship even though a reply to the inquiry from the router of the closest connection relationship is the same as former one, performs the re-notification for announcing that the publisher node stores the content to routers belonging to the same belonging network as that of the second router which newly becomes in the closest connection relationship.

[0065] (Mode 5) A publisher node, comprising: a router detection part that detects a router in the closest connection relationship among a plurality of routers, a notification part that performs a notification for announcing that the publisher node stores a content to a first router in the closest connection relationship, and a re-notification part, when it is detected that own positional shift resulted in a replacement of the router in the closest connection relationship, performs a re-notification for announcing that the publisher node stores the content to a second router which newly becomes in the closest connection relationship.

[0066] (Mode 6) A router, comprising: a notification processing part that, when receiving a notification for content storage, forwards the notification to the other router(s) in a connection relationship, and registers in a memory a publisher node or router, which is a source forwarder of the notification, as a forwarding destination of a content request derived from a subscriber node, and a re-notification processing part that, when receiving a re-notification for content storage, forwards the re-notification to the other router(s) in a connection relationship, and updates the forwarding destination of the content request to the publisher node or router, which is a source forwarder of the re-notification. (Mode 7) A system control method, wherein an information-centric networking system comprises: a plurality of routers that configure an information-centric network, a publisher node that delivers a content, and a subscriber node that requests the content, the publisher node executes: detecting a router in the closest connection relationship among the plurality of routers, performing a notification for announcing that the publisher node stores the content to a first router in the closest connection relationship, and when it is detected that own positional shift resulted in a replacement of the router in the closest connection relationship, performing a renotification for announcing that the publisher node stores the content to a second router which newly becomes in the closest connection relationship, and each of the plurality of routers executes: when receiving the notification, forwarding the notification to the other router(s) in a connection relationship and registering in a memory the publisher node or router, which is a source forwarder of the notification, as a forwarding destination of a content request derived from the subscriber node, and when receiving the re-notification, forwarding the re-notification to the other router(s) in a connection relationship and updating the forwarding destination of the content request to the publisher node or router, which is a source forwarder of the re-notification.

[0068] (Mode 8) A system control program, wherein an information-centric networking system comprises a plurality of routers that configure an information-centric network, a publisher node that delivers a content, and a subscriber node that requests the content, the publisher node is caused to execute: detecting a router in the closest connection relationship among the plurality of routers, performing a notification for announcing that the publisher node stores the content to a first router in the closest connection relationship, and when it is detected that own positional shift resulted in a replacement of the router in the closest connection relationship, performing a renotification for announcing that the publisher node stores the content to a second router which newly becomes in the closest connection relationship, and each of the plurality of routers is caused to execute: when receiving the notification, forwarding the notification to the other router(s) in a connection relationship and registering in a memory the publisher node or router, which is a source forwarder of the notification, as a forwarding destination of a content request derived from the subscriber node, and when receiving the re-notification, forwarding the re-notification to the other router(s) in a connection relationship and updating the forwarding destination of the content request to the publisher node or router, which is a source forwarder of the re-notification.

[0069] The features described in Mode 2 to 4 may be developed to the publisher node of Mode 5, the router of Mode 6, the system control method of Mode 7 and the system control program of Mode 8.

[0070] Herein, it is assumed that disclosure of each of the above Patent Literature is incorporated in the present application and may be used as a base or a part of the present invention as necessary. The example embodiment(s) or example(s) may be modified or adjusted within the scope of the entire disclosure of the present invention, inclusive of claims, based on the basic technical concept of the invention. In addition, a variety of combinations or selections (including partial selection or non-selection) of disclosed variety elements (each element in each claim, each element in each example embodiment or each example, etc.) may be made within the entire disclosure of the present invention. That is, the present invention, of course, may cover a variety of modifications or corrections that may be made by those skilled in the art in accordance with the entire disclosure of the present invention, inclusive of claims, and the technical concept of the present invention. In particular, a numerical range described in the present application should be interpreted as specifically describing any numerical value(s) or subrange(s) included within said range, even if not explicitly described. Furthermore, each of the disclosure in the above cited references shall be deemed to be included in the description of the present application, when necessary, as part of the description of the present invention, in whole or in part, in combination with the description of the present application, in accordance with the concept of the present invention. REFERENCE SIGNS LIST

[0071] 10 publisher node 11 router detection part 12 notification part 13 re-notification part 20 router 21 notification processing part 22 re-notification processing part 3 0 subscriber node 100 information-centric networking system

Claims

1. An information-centric networking system, comprising:a plurality of routers that configure an information-centric network,a publisher node that delivers a content, anda subscriber node that requests the content, wherein, the publisher node comprises:a router detection part that detects a router in the closest connection relationship among the plurality of routers,a notification part that performs a notification for announcing that the publisher node stores the content to a first router in the closest connection relationship, anda re-notification part, when it is detected that own positional shift resulted in a replacement of the router in the closest connection relationship, performs a re-notification for announcing that the publisher node stores the content to a second router which newly becomes in the closest connection relationship, andeach of the plurality of routers comprises:a notification processing part that, when receiving the notification, forwards the notification to the other router(s) in a connection relationship, and registers in a memory the publisher node or router, which is a source forwarder of the notification, as a forwarding destination of a content request derived from the subscriber node, anda re-notification processing part that, when receiving the renotification, forwards the re-notification to the other router(s) in a connection relationship, and updates the forwarding destination of the content request to the publisher node or router, which is a source forwarder of the re-notification.

2. The information-centric networking system according to Claim 1, whereinthe router detection part periodically makes an inquiry to the router in the closest connection relationship about its belonging network, andthe re-notification part, when a reply to the inquiry from the router in the closest connection relationship is different from a former reply, determines that own positional shift resulted in a replacement of the router in the closest connection relation and also resulted in a shift of own belonging network, and performs the re-notification for announcing that the publisher node stores the content to the second router which newly becomes in the closest connection relationship.

3. The information-centric networking system according to Claim 2, whereinthe notification part performs the notification for announcing a content name,the re-notification part preforms the re-notification for announcing a different content name and also announcing that the different content name indicates the same content as that indicated by the content name having been notified by the notification part.

4. The information-centric networking system according to Claim 3, whereinthe re-notification part, when it is detected that own positional shift results in a replacement of the router in the closest connection relationship even though a reply to the inquiry from the router of the closest connection relationship is the same as former one, performs the re-notification for announcing that the publisher node stores the content to routers belonging to the same belonging network as that of the second router which newly becomes in the closest connection relationship.

5. A publisher node, comprising:a router detection part that detects a router in the closest connection relationship among a plurality of routers,a notification part that performs a notification for announcingthat the publisher node stores a content to a first router in the closest connection relationship, anda re-notification part, when it is detected that own positional shift resulted in a replacement of the router in the closest connection relationship, performs a re-notification for announcing that the publisher node stores the content to a second router which newly becomes in the closest connection relationship.

6. A router, comprising:a notification processing part that, when receiving a notification for content storage, forwards the notification to the other router(s) in a connection relationship, and registers in a memory a publisher node or router, which is a source forwarder of the notification, as a forwarding destination of a content request derived from a subscriber node, anda re-notification processing part that, when receiving a renotification for content storage, forwards the re-notification to the other router(s) in a connection relationship, and updates the forwarding destination of the content request to the publisher node or router, which is a source forwarder of the re-notification.

7. A system control method, whereinan information-centric networking system comprises:a plurality of routers that configure an information-centric network,a publisher node that delivers a content, anda subscriber node that requests the content, the publisher node executes:detecting a router in the closest connection relationship among the plurality of routers,performing a notification for announcing that the publisher node stores the content to a first router in the closest connection relationship, andwhen it is detected that own positional shift resulted in a replacement of the router in the closest connection relationship,performing a re-notification for announcing that the publisher node stores the content to a second router which newly becomes in the closest connection relationship, andeach of the plurality of routers executes:when receiving the notification, forwarding the notification to the other router(s) in a connection relationship and registering in a memory the publisher node or router, which is a source forwarder of the notification, as a forwarding destination of a content request derived from the subscriber node, andwhen receiving the re-notification, forwarding the re-notification to the other routers in a connection relationship and updating the forwarding destination of the content request to the publisher node or router, which is a source forwarder of the re-notification.

8. The system control method according to claim 7, wherein the publisher node executes:periodically making an inquiry to the router in the closest connection relationship about its belonging network, andwhen a reply to the inquiry from the router in the closest connection relationship is different from a former reply, determining that own positional shift resulted in a replacement of the router in the closest connection relation and also resulted in a shift of own belonging network, and performing the re-notification for announcing that the publisher node stores the content to the second router which newly becomes in the closest connection relationship.

9. The system control method according to claim 8, wherein the publisher node executes:performing the notification for announcing a content name,preforming the re-notification for announcing a different content name and also announcing that the different content name indicates the same content as that indicated by the content name having been notified. [Claim 1 0]The system control method according to claim 9, wherein the publishernode executes:when it is detected that own positional shift results in a replacement of the router in the closest connection relationship even though a reply to the inquiry from the router of the closest connection relationship is the same as former one, performing the re-notification for announcing that the publisher node stores the content to routers belonging to the same belonging network as that of the second router which newly becomes in the closest connection relationship.

11. A system control program, whereinan information-centric networking system comprises:a plurality of routers that configure an information-centric network,a publisher node that delivers a content, anda subscriber node that requests the content,the publisher node is caused to execute:detecting a router in the closest connection relationship among the plurality of routers,performing a notification for announcing that the publisher node stores the content to a first router in the closest connection relationship, andwhen it is detected that own positional shift resulted in a replacement of the router in the closest connection relationship, performing a re-notification for announcing that the publisher node stores the content to a second router which newly becomes in the closest connection relationship, andeach of the plurality of routers is caused to execute:when receiving the notification, forwarding the notification to the other router(s) in a connection relationship and registering in a memory the publisher node or router, which is a source forwarder of the notification, as a forwarding destination of a content request derived from the subscriber node, andwhen receiving the re-notification, forwarding the re-notification to the other router(s) in a connection relationship and updating theforwarding destination of the content request to the publisher node or router, which is a source forwarder of the re-notification. [Claim 1 2]The system control program according to claim 11, wherein the publisher node is caused to execute:periodically making an inquiry to the router in the closest connection relationship about its belonging network, andwhen a reply to the inquiry from the router in the closest connection relationship is different from a former reply, determining that own positional shift resulted in a replacement of the router in the closest connection relation and also resulted in a shift of own belonging network, and performing the re-notification for announcing that the publisher node stores the content to the second router which newly becomes in the closest connection relationship. [Claim 1 3 ]The system control program according to claim 12, wherein the publisher node is caused to execute:performing the notification for announcing a content name,preforming the re-notification for announcing a different content name and also announcing that the different content name indicates the same content as that indicated by the content name having been notified. [Claim 1 4]The system control program according to claim 13, wherein the publisher node is caused to execute:when it is detected that own positional shift results in a replacement of the router in the closest connection relationship even though a reply to the inquiry from the router of the closest connection relationship is the same as former one, performing the re-notification for announcing that the publisher node stores the content to routers belonging to the same belonging network as that of the second router which newly becomes in the closest connection relationship.

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