JP4827819B2 - Network communication method and apparatus - Google Patents

Description

  The present invention relates to communication in a network, and more particularly to multicast communication in a network.

  In a computer network such as the Internet, multicast is known in which information is simultaneously transmitted from one transmitting terminal to a plurality of receiving terminals. In multicast, data sent from a sending terminal (called “multicast packet” or “multicast frame”) is replicated in a router on the communication path, and each of the replicated data is joined to a plurality of multicast groups. Sent to one of the receiving terminals. Multicast is used for real-time multimedia communication in which a large amount of traffic such as streaming or video conferencing is desired, for example, because the amount of transmitted data is small compared to a method in which data is individually transmitted from a transmitting terminal to each receiving terminal.

  In multicast, route control by a router according to a multicast route control protocol is performed so that data is sent only to receiving terminals participating in the multicast group. As the multicast route control protocol, for example, PIM-SM (Protocol Independent Multispace Sparse-Mode) is used (see Non-Patent Document 1).

IETF, “Protocol Independent Multicast Sparse-Mode (PIM-SM): Protocol Specification”, RFC2362.

  In route control according to PIM-SM, RPF (Reverse Path Forwarding) calculation is used. That is, a router that has received a request to join a certain multicast group from the downstream side detects one adjacent router (called “RPF Neighbor”) on the route in the direction of the multicast transmission terminal from the unicast route table, and is detected. Multicast route information with the adjacent router is registered, and a multicast group join request (referred to as “PIM Join message”) is transmitted to the adjacent router. Multicast communication route from the sending terminal to the receiving terminal is performed by such registration of multicast route information and transmission of the multicast group join request being performed in the router on the route between the multicast sending terminal and the receiving terminal. Is set.

  In a multicast route setting using a redundant route or ECMP (Equal Cost Multipath), a plurality of neighboring routers may be detected. In such a case, one of the detected plurality of neighboring routers is registered in the multicast route information, and multicast data transfer is performed using the route through the registered neighboring router. Here, for example, when a failure occurs in the route, the data transfer route can be switched by newly registering another adjacent router. However, when switching data transfer paths, a long communication interruption period may occur due to re-detection of neighboring routers, re-registration of multicast path information, transmission of a multicast group join request, and the like.

  Such a problem is not limited to multicast communication according to PIM-SM, but is a problem common to multicast communication in a network in general.

  The present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide a technique that can improve the reliability of multicast communication in a network.

  In order to solve at least a part of the above problems, the present invention can be realized as the following forms or application examples.

Application Example 1 A network communication device,
Multiple network interfaces;
A path setting unit that searches an upstream interface that is an upstream network interface of multicast from the plurality of network interfaces, and sets one of the detected upstream interfaces as an active interface;
The multicast data can be received via the plurality of upstream interfaces, and only the multicast data received via the upstream interface set as the active interface is sent to the downstream side of the multicast. A relay processing unit that relays with
A network communication device comprising: a switching setting unit configured to set another upstream interface as a new active interface instead of the upstream interface set as the active interface at a predetermined timing.

  In this network communication device, multicast data is received via a plurality of upstream interfaces, and only multicast data received via an upstream interface set as an active interface is relayed downstream of the multicast. The Then, at a predetermined timing, another upstream interface is set as a new active interface, and after that, only multicast data received via the upstream interface set as the new active interface is transferred to the downstream side of the multicast. Relayed. Therefore, in this network communication apparatus, it is possible to quickly switch multicast paths, and to improve the reliability of multicast communication in the network.

[Application Example 2] The network communication device according to Application Example 1,
When the plurality of upstream interfaces are detected, the path setting unit sends a request for transmission of the multicast data to each of the plurality of upstream interfaces via each of the plurality of upstream interfaces. A network communication device issued to the side.

  In this network communication apparatus, since a multicast data transmission request to each of the plurality of upstream interfaces is issued to the upstream side of the multicast via each of the plurality of upstream interfaces, the multicast data is transmitted via the plurality of upstream interfaces. Data can be received.

[Application Example 3] The network communication device according to Application Example 1 or Application Example 2,
The path control unit creates path information that identifies the detected upstream interface and the set active interface,
The relay processing unit relays the multicast data according to the route information,
The switching setting unit is a network communication device that sets a new active interface by changing the route information.

  In this network communication device, multicast data can be relayed in accordance with route information specifying an active interface, and a new active interface can be set by changing the route information.

[Application Example 4] The network communication device according to any one of Application Example 1 to Application Example 3,
The path control unit creates switching information for specifying the other upstream interface to be set as the new active interface,
The switching setting unit is a network communication device that sets a new active interface according to the switching information.

  In this network communication device, since the other upstream interface to be set as the new active interface is specified by the switching information, the setting of the new active interface can be executed more quickly.

[Application Example 5] The network communication apparatus according to any one of Application Examples 1 to 4,
The network communication device, wherein the predetermined timing is a time when a predetermined failure that makes it impossible to receive the multicast data via the upstream interface set as the active interface is detected.

  In this network communication apparatus, when a predetermined failure that makes it impossible to receive multicast data is detected, the multicast route can be switched quickly.

[Application Example 6] The network communication device according to Application Example 5,
The predetermined failure includes a failure of the upstream interface set as the active interface, a failure of an adjacent network communication device adjacent to the network communication device via the upstream interface set as the active interface, and the multicast And a communication path failure from the transmission source to the upstream interface set as the active interface.

  In this network communication device, the failure of the upstream interface set as the active interface, the failure of the adjacent network communication device adjacent to the network communication device via the upstream interface set as the active interface, the active interface from the multicast source When at least one of the communication path failures up to the upstream interface set as is detected, the multicast path can be switched quickly.

[Application Example 7] The network communication device according to Application Example 5 or Application Example 6,
A network communication device comprising a failure detection unit for detecting the predetermined failure.

  In this network communication apparatus, when a failure is detected by the failure detection unit, the multicast route can be switched quickly.

[Application Example 8] The network communication device according to Application Example 7,
The network communication apparatus, wherein the failure detection unit can use a failure detection protocol.

  In this network communication apparatus, when a failure is detected using a failure detection protocol, a multicast path can be switched quickly.

[Application Example 9] The network communication device according to Application Example 1,
The network communication device, wherein the process by the route setting unit and the process by the switching setting unit are executed independently of each other.

  In this network communication apparatus, the processing by the route setting unit and the processing by the switching setting unit are executed independently of each other, so that even when the processing by the route setting unit is being executed, the multicast route is quickly switched. be able to.

[Application Example 10] The network communication device according to Application Example 1,
The route control unit creates switching information for specifying the predetermined timing,
The switching setting unit is a network communication device that sets a new active interface according to the switching information.

  In this network communication apparatus, the timing for switching the multicast path can be set in advance, and the multicast path can be switched quickly at a predetermined timing registered in advance.

  It should be noted that the present invention can be realized in various modes. For example, a network communication method and apparatus, a network relay method and apparatus, a data transfer method and apparatus, a route setting method and apparatus, and a method or apparatus of these methods or apparatuses The present invention can be realized in the form of a computer program for realizing the function, a recording medium storing the computer program, a data signal including the computer program and embodied in a carrier wave, and the like.

Next, embodiments of the present invention will be described in the following order based on examples.
A. Example:
A-1. Network configuration:
A-2. Multicast route setting processing:
A-3. Route switching processing at the time of failure:
B. Variations:

A. Example:
A-1. Network configuration:
FIG. 1 is an explanatory diagram schematically showing a network configuration in an embodiment of the present invention. The network 10 of the present embodiment is a multicast network that supports PIM-SM, which is a multicast routing protocol. The network 10 includes a transmission terminal 300 as a data transmission source in a multicast group, two reception terminals 200 that finally participate in the multicast group and receive multicast data, and the transmission terminal 300 and the reception terminal 200. And six routers 100 as network communication devices that relay data communicated between them. Components in the network 10 are connected via a link 400. The link 400 is a data transmission path, and is configured by, for example, a UTP cable, an STP cable, an optical fiber, a coaxial cable, or radio.

  In this specification, in order to distinguish individual components in the network 10, an identification code for distinguishing each component may be added to the end of a code representing the component. For example, there are six routers 100 in the network 10 of this embodiment, and each of the six routers 100 may be represented as routers 100A, 100B, 100C, 100D, 100E, and 100F. However, when it is not necessary to individually distinguish the same type of components, the above identification code added to the end of the code is omitted. Further, in the present specification, there is a case where the identification code is added to the name of the component and called. For example, the router 100A may be called router A.

  In this specification, data transmitted and received in multicast communication is also referred to as a multicast packet. Further, data transmitted and received in unicast communication in which a transmission terminal and a reception terminal perform one-to-one communication is also referred to as a unicast packet.

  As shown in FIG. 1, the transmission terminal 300A (transmission terminal A) is connected to a router 100D (router D). The receiving terminal 200A (receiving terminal A) is connected to the router 100A (router A). The router 100A is connected to the router 100B (router B) and the router 100C (router C), and the router 100B and the router 100C are connected to the router 100D. The receiving terminal 200B (receiving terminal B) is connected to the router 100E (router E). The router 100E is connected to the router 100F (router F), and the router 100F is connected to the router 100D.

  FIG. 2 is an explanatory diagram schematically showing the configuration of the router in the present embodiment. FIG. 2 shows the configuration of the router 100A (router A) (see FIG. 1). The router 100A includes a communication unit 140 that performs data communication with other devices (the router 100 and the receiving terminal 200), and a control unit 110 that controls data communication in the communication unit 140.

  The communication unit 140 is configured by, for example, an ASIC (specific application IC), and includes a plurality of network interfaces 142 that function as data input / output holes. One network interface 142a (also referred to as “network interface a” or “IFa”) is connected to the router 100B (router B) via the link 400. Another network interface 142b (also referred to as “network interface b” or “IFb”) is connected to the router 100C (router C) via the link 400. Further, another network interface 142c (also referred to as “network interface c” or “IFc”) is connected to the receiving terminal 200A (receiving terminal A) via the link 400.

  The control unit 110 includes a CPU 112 and an internal memory 114. The internal memory 114 is configured by, for example, a RAM or a flash memory. In FIG. 1, the internal memory 114 is shown as one memory area, but the internal memory 114 may be composed of a plurality of memory areas.

  The internal memory 114 includes a unicast route setting unit 122, a unicast packet relay processing unit 124, a multicast packet route setting unit 126, a multicast packet relay processing unit 128, a failure detection unit 132, and a switching setting unit 134. , Is stored. The unicast route setting unit 122 is a computer program for setting a route for unicast communication in which a transmission terminal and a reception terminal perform one-to-one communication. A unicast packet relay processing unit 124 is used in unicast communication. A computer program for performing relay processing of a unicast packet. The multicast packet route setting unit 126 is a computer program for setting a route for multicast communication, and the multicast packet relay processing unit 128 is a computer program for performing multicast packet relay processing in multicast communication. The failure detection unit 132 is a computer program for detecting a failure in the network 10, and the switching setting unit 134 is a computer program for switching an active interface described later. The CPU 112 reads out these computer programs from the internal memory 114 and executes them, thereby realizing the functions of the above-described units.

  The internal memory 114 further stores a unicast route calculation table UCT, a unicast relay route table URT, a multicast route calculation table MCT, a multicast relay route table MRT, and a switching opportunity registration table SOT. .

  The unicast route calculation table UCT is a table used for route calculation / setting in unicast communication, and is created by the unicast route setting unit 122. The unicast relay route table URT is a table that is referred to when a packet is relayed by the unicast packet relay processing unit 124 in unicast communication, and the unicast route calculation notified by the unicast route setting unit 122. Created / changed / deleted based on contents of table UCT. Since the unicast route calculation table UCT and the unicast relay route table URT are used in conventional unicast communication, the description of the specific contents is omitted. The contents of the multicast route calculation table MCT, the multicast relay route table MRT, and the switching opportunity registration table SOT will be described later.

  The configuration of the router 100 (routers 100B to 100F) other than the router 100A on the network 10 (FIG. 1) is the same as the configuration of the router 100A shown in FIG. Some of the components may not be included, or other components not included in the router 100A may be included. The connection destination of each network interface 142 of the other router 100 is a connection destination according to the connection configuration of the network 10.

A-2. Multicast route setting processing:
FIG. 3 is a flowchart showing the flow of the multicast route setting process in the present embodiment. FIG. 4 is an explanatory diagram showing an overview of multicast route setting processing in the present embodiment. The multicast path setting process is a process for setting a relay path for a multicast packet in the router 100A (FIG. 1).

  In step S110 (FIG. 3), the router 100A (router A) receives a request to join a multicast group from the receiving terminal 200A (receiving terminal A) (see FIG. 4). In this embodiment, it is assumed that this participation request is a request to join a multicast group whose multicast transmission source is the transmission terminal 300A (transmission terminal A). The participation request from the receiving terminal 200A is received via the network interface 142c (IFc) (FIG. 2).

  In this specification, the transmission terminal side of multicast communication is referred to as the upstream side, and the reception terminal side is referred to as the downstream side. For example, the network interface 142c (IFc) of the router 100A is a network interface on the downstream side of the multicast.

  In step S120 (FIG. 3), the multicast packet route setting unit 126 (FIG. 2) of the router 100A searches for an adjacent router on the upstream side of the multicast. Specifically, the multicast packet route setting unit 126 specifies the address of the transmission source (transmission terminal 300A) included in the received multicast group participation request, and refers to the entry of the unicast route calculation table UCT (FIG. 2). Thus, the network interface 142 in the transmission source direction is detected. The router 100 connected to the detected network interface 142 is set as an adjacent router.

  If no upstream neighboring router is detected in step S120 (step S130: No), the multicast route setting process is terminated. On the other hand, when an upstream adjacent router is detected (step S130: Yes), the multicast packet route setting unit 126 registers the multicast route calculation table MCT (FIG. 2) (step S140). In the network 10 (FIG. 1) of the present embodiment, since the router 100B and the router 100C are detected as adjacent routers, the multicast route calculation table MCT is registered.

  FIG. 5 is an explanatory diagram showing an example of the contents of the multicast route calculation table MCT. The multicast route calculation table MCT includes, for each multicast group, the multicast transmission source address (“source” item), the multicast destination address (“group” item), the neighboring upstream router and the neighboring multicast. A network interface (item of “adjacent router (IF)”) used for connection with the router is registered. The multicast packet route setting unit 126 includes a source address (for example, “source 1”) and a destination address (for example, “group 1”) specified by the received participation request, an adjacent router, and a network interface (router B (IFa ) And router C (IFb)) are registered in the multicast route calculation table MCT.

  The multicast packet route setting unit 126 further selects one of the neighboring routers by, for example, hash calculation or metric value reference of the unicast route, and sets the network interface 142 used for connection with the selected neighboring router as the active interface. Set as. That is, the multicast packet route setting unit 126 sets one of the detected upstream network interfaces 142 as an active interface. The multicast packet route setting unit 126 registers the network interface 142 set as the active interface in the item “active interface” of the multicast route calculation table MCT. In the example of FIG. 5, the network interface 142a (IFa) (see FIG. 2) connected to the router 100B is registered as an active interface.

  The multicast packet route setting unit 126 registers the network interface 142 on the downstream side of the multicast in the item “output interface” of the multicast route calculation table MCT. In the example of FIG. 5, the network interface 142c (IFc) (see FIG. 2) connected to the receiving terminal 200A is registered as a downstream network interface.

  In step S150 (FIG. 3), the multicast packet route setting unit 126 (FIG. 2) transmits a multicast group participation request to all registered neighboring routers. In the network 10 of the present embodiment, the router 100B and the router 100C are registered as adjacent routers (see FIG. 5), so the multicast packet path setting unit 126 includes the network interface 142a (IFa) and the network interface 142b (IFb). Then, a multicast group participation request is transmitted to the router 100B and the router 100C (see FIG. 4). As a result, multicast group participation requests from the two network interfaces 142 (IFa and IFb) are transmitted from the router 100A to the upstream side. The multicast group participation request is transmitted as, for example, a PIM Join message.

  In step S160 (FIG. 3), the multicast packet route setting unit 126 (FIG. 2) registers the switching opportunity registration table SOT. FIG. 6 is an explanatory diagram showing an example of the contents of the switching opportunity registration table SOT. In the switching opportunity registration table SOT, an active interface and a secondary interface other than the active interface among the network interfaces 142 on the upstream side of the multicast are registered for each multicast group. In this embodiment, the network interface 142a (IFa) is registered as an active interface in the switching opportunity registration table SOT, and the network interface 142b (IFb), which is an upstream network interface other than the active interface, is registered as a secondary interface.

  The multicast packet path setting unit 126 also registers the trigger (timing) for switching the active interface in the item “switch trigger” of the switch trigger registration table SOT. In this embodiment, the failure of the active interface, the failure of the adjacent router on the communication path via the active interface, the failure of the communication path from the transmission terminal 300A to the active interface, and the like are registered as the switching trigger. These failures are failures that make it impossible for the router 100A to receive the multicast packet sent from the transmission terminal 300A via the active interface. Furthermore, in this embodiment, a time when a failure of the network 10 is detected by a failure detection protocol (for example, BFD (Bidirectional Forwarding Detection)) is registered as a switching trigger.

  In step S170 (FIG. 3), the multicast packet relay processing unit 128 (FIG. 2) registers the multicast relay route table MRT based on the registration result of the multicast route calculation table MCT notified by the multicast packet route setting unit 126. . FIG. 7 is an explanatory diagram showing an example of the contents of the multicast relay route table MRT. The multicast relay route table MRT includes, for each multicast group, a multicast transmission source address (“source” item), a multicast destination address (“group” item), and a downstream network interface (“output interface”). Are registered). In the multicast relay route table MRT, all upstream network interfaces 142 (network interfaces 142 connected to all adjacent routers) are registered in the item “input interface”. Further, an identifier indicating whether or not each input interface is set as an active interface is registered in the item “active identifier”. In the example of FIG. 7, in the “active identifier” item, “1” indicates that the input interface is set as an active interface, and “0” indicates that the input interface is not set as an active interface. Yes. Therefore, the active identifier of the network interface 142a (IFa) set as the active interface is “1”.

  As described above, the router 100A that has received the multicast group join request from the receiving terminal 200A executes the multicast route setting process (FIG. 3). The neighboring routers of the router 100A (in this embodiment, the router 100B and the router 100C) that have received the participation request transmitted in step S150 of the multicast path setting process by the router 100A similarly execute the multicast path setting process. In this process, a multicast group participation request is transmitted from the router 100B and the router 100C to the router 100D (see FIG. 4). As a result, the multicast group join request arrives at the router 100D that accommodates the transmitting terminal 300A via two paths, and two communication paths from the transmitting terminal 300A to the receiving terminal 200A for multicast are set. In addition, as shown in FIG. 4, the multicast group participation request transmitted from the receiving terminal 200B to the router 100E similarly reaches the router 100D via the router 100E and the router 100F, and is transmitted from the transmitting terminal 300A. A multicast communication path to the receiving terminal 200B is set.

  FIG. 8 is an explanatory diagram showing the flow of a multicast packet. FIG. 8 shows the flow of multicast packets in a state where multicast communication paths from the transmission terminal 300A to the reception terminals 200A and 200B are set as shown in FIG.

  In the multicast communication in the network 10 of the present embodiment, the multicast packet MP sent from the transmission terminal 300A to the multicast group address is transferred by the relay processing by the multicast packet relay processing unit 128 (FIG. 2) of each router 100, Finally, it is received by receiving terminal 200A and receiving terminal 200B.

  Specifically, the multicast packet MP transmitted from the transmission terminal 300A is received by the router 100D. The router 100D duplicates the multicast packet MP and transfers it to the three downstream routers (routers 100B, 100C, and 100F). The multicast packet MP transmitted to the router 100F is transferred to the receiving terminal 200B via the router 100E.

  The multicast packet MP transmitted to the router 100B is transferred to the router 100A, and the multicast packet MP transmitted to the router 100C is also transferred to the router 100A. Here, the multicast packet relay processing unit 128 (FIG. 2) of the router 100A downstream only the multicast packet MP received by the network interface 142a (IFa) (see FIG. 7) which is the network interface 142 set as the active interface. To the receiving terminal 200A via the network interface 142c (IFc) on the side. On the other hand, the multicast packet relay processing unit 128 discards the multicast packet MP received by the network interface 142b (IFb), which is the network interface 142 that is not set as an active interface, without relaying.

  As described above, the router 100A receives the multicast packet MP from the two upstream neighboring routers via the two network interfaces 142 (IFa and IFb), and receives the multicast packet MP received by one active interface (IFa). Only the multicast packet MP received by the other network interface 142 (IFb) is discarded.

A-3. Route switching processing at the time of failure:
FIG. 9 is a flowchart showing the flow of a failure path switching process in this embodiment. FIG. 10 is an explanatory diagram showing an outline of the failure path switching process in the present embodiment. The failure path switching process is a process of switching the path by switching the active interface when the router 100A detects a failure of the multicast path via the active interface.

  In step S210 (FIG. 9), the failure detection unit 132 (FIG. 2) of the router 100A (router A) detects a failure. The failure detection may be performed by other methods. In the present embodiment, it is assumed that a failure T that has occurred on the route between the router 100A and the router 100B is detected as shown in FIG.

  In step S220 (FIG. 9), the switching setting unit 134 (FIG. 2) determines whether or not there is a multicast registration with the failed part upstream. If it is determined that there is no such multicast registration (step S220: No), there is no need to switch the multicast route, and the process is terminated.

  When it is determined that there is such multicast registration (step S220: Yes), the switching setting unit 134 determines whether or not the position of the failure T is on the multicast route via the active interface. (Step S230). If it is determined that the location of the failure T is not on the multicast route via the active interface (step S230: No), the processing is terminated because there is no need for route switching.

  When it is determined that the position of the failure T is on the multicast route via the active interface (step S230: Yes), the switching setting unit 134 registers the failure T in the switching opportunity registration table SOT (FIG. 6). It is determined whether it corresponds to the changed switching opportunity (step S240). If it is determined that the failure T does not correspond to the registered switching trigger (step S240: No), the process is terminated.

  When it is determined that the failure T corresponds to the registered switching trigger (step S240: Yes), the switching setting unit 134 determines whether or not there are a plurality of upstream adjacent routers (step S250). If it is determined that there are not a plurality of adjacent routers on the upstream side (step S250: No), since the path cannot be switched, the multicast setting is deleted by the switching setting unit 134 (step S290). The process is terminated.

  When it is determined that there are a plurality of upstream adjacent routers (step S250: Yes), the switching setting unit 134 refers to the switching timing registration table SOT (FIG. 6), and the network interface registered as the secondary interface 142 is detected (step S260). When a plurality of network interfaces 142 are registered as secondary interfaces in the switching opportunity registration table SOT, one network interface 142 is selected from them. In the example of FIG. 6, the network interface 142b (IFb) is detected because the network interface 142b (IFb) is registered as the only secondary interface in the switching opportunity registration table SOT.

  In step S270 (FIG. 9), the switching setting unit 134 performs update registration of the multicast relay route table MRT. Specifically, the switching setting unit 134 changes the item of “active identifier” in the multicast relay route table MRT (FIG. 7) so that one secondary interface detected in step S260 is newly registered as an active interface. To do. In the example of FIG. 7, the active identifier corresponding to the network interface 142b (IFb) is changed from “0” to “1”. Conversely, the active identifier corresponding to the network interface 142a (IFa) that was the active interface before the switching is changed from “1” to “0”.

  After the multicast relay route table MRT (FIG. 7) is updated and registered in step S270, the multicast packet relay processing unit 128 executes multicast packet relay processing according to the multicast relay route table MRT after the update registration. Therefore, as shown in FIG. 10, the multicast packet relay processing unit 128 receives the multicast packet MP received from the router 100C via the network interface 142b (IFb) via the downstream network interface 142c (IFc). Relay to terminal 200A.

  In step S280 (FIG. 9), the multicast packet route setting unit 126 that has received the notification from the switching setting unit 134 (FIG. 2) performs update registration of the multicast route calculation table MCT (FIG. 5). Note that the update registration of the multicast relay route table MRT by the switching setting unit 134 and the update registration of the multicast route calculation table MCT by the multicast packet route setting unit 126 are performed independently of each other.

  As described above, in the network 10 of the present embodiment, the router 100A can receive multicast packets via the plurality of upstream network interfaces 142. The router 100A relays only the multicast packet received via the network interface 142 set as the active interface to the downstream side. In addition, when a failure occurs on a multicast route via an active interface, the multicast route can be switched simply by switching the active interface, and the communication disconnection time can be shortened. Therefore, the router 100A of the present embodiment can improve the reliability of multicast communication in the network.

  Further, in the network 10 of this embodiment, the router 100A has registered in advance all neighboring routers, active interfaces, secondary interfaces, etc. on the upstream side, and has received multicast packets from all neighboring routers. When switching the route, it is not necessary to rediscover neighboring routers, select a new active interface, or send a multicast group join request, and can realize rapid switching.

B. Variations:
The present invention is not limited to the above-described examples and embodiments, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

B1. Modification 1:
The configuration of the network 10 and the router 100A in the above embodiment is merely an example, and the configuration of the network 10 and the router 100A can be other configurations. Further, the present invention is not limited to a router, but can be applied to other network communication devices such as a layer 2 switch, a layer 3 switch, and an access point.

B2. Modification 2:
In the above embodiment, all detected upstream neighboring routers are registered in the multicast route calculation table MCT. However, as long as a plurality of neighboring routers are registered, it is not always necessary to register all neighboring routers.

B3. Modification 3:
In the above embodiment, the multicast route is switched when the failure T occurs. However, the timing for switching the multicast route is not necessarily limited to the time when the failure T occurs. It may be the timing.

B4. Modification 4:
In the above embodiment, the multicast relay route table MRT is registered by the multicast packet relay processing unit 128, but the multicast relay route table MRT may be registered by the multicast packet route setting unit 126.

B5. Modification 5:
In the above embodiment, a part of the configuration realized by hardware may be replaced with software, and conversely, a part of the configuration realized by software may be replaced by hardware. For example, the communication unit 140 does not need to be configured by an ASIC, and the function of the communication unit 140 may be realized by software, for example.

It is explanatory drawing which shows schematically the structure of the network in the Example of this invention. It is explanatory drawing which shows schematically the structure of the router in a present Example. It is a flowchart which shows the flow of the multicast route setting process in a present Example. It is explanatory drawing which shows the outline | summary of the multicast path | route setting process in a present Example. It is explanatory drawing which shows an example of the content of the multicast route calculation table MCT. It is explanatory drawing which shows an example of the content of the switching opportunity registration table SOT. It is explanatory drawing which shows an example of the content of the multicast relay routing table MRT. It is explanatory drawing which shows the flow of a multicast packet. It is a flowchart which shows the flow of the path switching process at the time of a failure in a present Example. It is explanatory drawing which shows the outline | summary of the path switching process at the time of a failure in a present Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Network 100 ... Router 110 ... Control part 112 ... CPU
DESCRIPTION OF SYMBOLS 114 ... Internal memory 122 ... Unicast route setting part 124 ... Unicast packet relay process part 126 ... Multicast packet route setting part 128 ... Multicast packet relay process part 132 ... Failure detection part 134 ... Switching setting part 140 ... Communication part 142 ... Network Interface 200 ... receiving terminal 300 ... transmitting terminal 400 ... link

Claims (10)

A network communication device,
Multiple network interfaces;
An upstream interface which is a network interface on the upstream side of multicast is searched from among the plurality of network interfaces, and when the plurality of upstream interfaces are detected, transmission of the multicast data to each of the plurality of upstream interfaces A route setting unit that sends a request to the upstream side of the multicast via each of the plurality of upstream interfaces, and sets any one of the upstream interfaces that sent the multicast data transmission request as an active interface; ,
The multicast data can be received via the plurality of upstream interfaces, and only the multicast data received via the upstream interface set as the active interface is sent to the downstream side of the multicast. A relay processing unit that relays with
A network communication device comprising: a switching setting unit configured to set another upstream interface as a new active interface instead of the upstream interface set as the active interface at a predetermined timing. The network communication device according to claim 1 ,
The route setting unit creates route information that identifies the detected upstream interface and the set active interface,
The relay processing unit relays the multicast data according to the route information,
The switching setting unit is a network communication device that sets a new active interface by changing the route information. The network communication device according to claim 1 or 2 ,
The path setting unit creates switching information for specifying the other upstream interface to be set as the new active interface,
The switching setting unit is a network communication device that sets a new active interface according to the switching information. A network communication device according to any one of claims 1 to 3 ,
The network communication device, wherein the predetermined timing is a time when a predetermined failure that makes it impossible to receive the multicast data via the upstream interface set as the active interface is detected. The network communication device according to claim 4 ,
The predetermined failure includes a failure of the upstream interface set as the active interface, a failure of an adjacent network communication device adjacent to the network communication device via the upstream interface set as the active interface, and the multicast And a communication path failure from the transmission source to the upstream interface set as the active interface. The network communication device according to claim 4 or 5 , further comprising:
A network communication device comprising a failure detection unit for detecting the predetermined failure. The network communication device according to claim 6 ,
The network communication apparatus, wherein the failure detection unit can use a failure detection protocol. The network communication device according to claim 1,
The network communication device, wherein the process by the route setting unit and the process by the switching setting unit are executed independently of each other. The network communication device according to claim 1,
The route setting unit creates switching information for specifying the predetermined timing,
The switching setting unit is a network communication device that sets a new active interface according to the switching information. A network communication method,
(A) An upstream interface that is a network interface on the upstream side of multicast is searched from among a plurality of network interfaces, and the multicast data to each of the plurality of upstream interfaces when a plurality of the upstream interfaces are detected Sending the transmission request to the upstream side of the multicast via each of the plurality of upstream interfaces, and setting any one of the upstream interfaces that sent the multicast data transmission request as an active interface; ,
(B) The multicast data is received via a plurality of the upstream interfaces, and only the multicast data received via the upstream interface set as the active interface is transmitted to the downstream side of the multicast. And relaying process,
(C) A step of setting another upstream interface as the new active interface instead of the upstream interface set as the active interface at a predetermined timing.

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