JP2013118537A - Multicast distribution system, router, and multicast distribution method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems about which load is imposed on a router of a distribution source and a line of the distribution source router and the topology of a network becomes unstable in a mesh virtual network.SOLUTION: A multicast distribution system is characterized that a multicast distribution source router and at least one of a plurality of multicast distribution destination routers have in a storage unit a learning message including the address of an adjacent distribution destination router permitting reception of multicast traffic and an interface for distributing the multicast traffic to the adjacent distribution router, and transmit the learning message to the adjacent distribution destination router, and the adjacent distribution destination router having received the learning message selects an interface to which the multicast traffic is distributed on the basis of the learning message, and creates a multicast distribution tree.

Description

  The present invention relates to a multicast distribution system, a router, and a multicast distribution method.

  As background arts in this technical field, routers that constitute a multicast system are PIM-SM (Protocol Independent Multicast-Sparse Mode), PIM-DM (Protocol Independent Multicast-Dense Mode), DVMRP (Distance Vector Mect. A multicast routing protocol is used to construct a multicast tree.

  These multicast routing protocols generate a multicast tree so as to have a minimum number of hops in order to reduce communication delay.

  In Japanese Unexamined Patent Application Publication No. 2008-263449, “in a mesh virtual network to which a plurality of routers R are connected, the router Rs performs multicast distribution to a multicast group corresponding to an application. When the communication characteristics (bandwidth, communication delay) of the group exceed the threshold value, the number of branches and the depth of the multicast tree that distributes packets from the router Rs are updated, and reconstruction of the multicast tree is started. When constructing a multicast tree, referring to the path characteristics (bandwidth, communication delay) of the mesh virtual network, a communication path having a sufficient path characteristic is preferentially selected, and the router Rs performs routing based on the multicast tree. Generate a table ".

JP 2008-263449 A

  In a mesh virtual network, there is a problem that a load is applied to a distribution source router and a distribution source router line, and a problem that the network topology becomes unstable.

  Further, Patent Document 1 describes a distribution method for performing multicast distribution by selecting a communication path that satisfies communication characteristics required by a multicast group. However, the communication method of Patent Document 1 has a problem that unicast communication is greatly affected, and a problem that traffic detours in the event of a failure are not considered.

  Therefore, an object of the present application is to provide a multicast distribution system and a multicast distribution method in a mesh virtual network that solve the above problems.

In order to solve the above problems, for example, the configurations described in the claims below are employed.
A multicast distribution system comprising a server for distributing multicast traffic, a distribution source router connected to the server, a plurality of distribution destination routers connected to the distribution source router, and the plurality of distribution destination routers, wherein the distribution source The router and the plurality of distribution destination routers are connected to each other to form a mesh-structured network, and at least one of the distribution source router and the plurality of distribution destination routers is adjacent to each other that allows the reception of the multicast traffic. A learning message including an address for distributing the multicast traffic to the adjacent destination router in the storage unit, the learning message being transmitted to the adjacent destination router, and the learning message being transmitted to the adjacent destination router. The received adjacent destination router receives the Based on learning message, select an interface in which the multicast traffic is delivered to solve the above problems by the multicast distribution system, characterized in that to create a multicast distribution tree.

  According to the present invention, in a mesh virtual network, a flexible multicast network topology can be designed in response to the problem that a load is applied to a distribution source router, so that the load on the distribution source router is reduced.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is a figure showing the network structure of a logical path full mesh. It is a figure showing the detailed connection of the distribution origin router 105. FIG. FIG. 3 is a diagram illustrating a detailed connection of a router 106. FIG. 3 is a diagram illustrating a detailed connection of a router 107. FIG. 3 is a diagram illustrating a detailed connection of a router 108. FIG. 3 is a diagram illustrating a detailed connection of a router 109. It is a setting table and a message distribution table for RPF learning that the distribution source router 105 and the routers 106 to 109 have. These are an RPF learning table and a multicast routing table that the distribution source router 105 and the routers 106 to 109 have. An RPF learning message possessed by the distribution source router 105 is distribution information and an RPF learning table. It is the RPF learning message distribution information and the RPF learning table which the distribution destination router 106 has. It is the RPF learning message distribution information and RPF learning table which the distribution destination router 107 has. It is the distribution information and RPF learning table of the RPF learning message which the distribution destination router 108 has. It is the RPF learning message distribution information and the RPF learning table which the distribution destination router 109 has. It is the registration flowchart of RPFneighbor and RPF interface based on the RPF learning message distribution of the distribution source router 105 and the distribution destination routers 106-109. It is a distribution flow chart of multicast traffic after an interface of RPF neighbor and RPF is determined. It is a flowchart which selects an RPF interface and RPFneighbor. It is a multicast routing table that the distribution source router 105 has. It is a RPF learning table and a multicast routing table which the delivery destination router 106 has. It is an RPF learning table and a multicast routing table which the delivery destination router 107 has. It is a RPF learning table and a multicast routing table which the delivery destination router 108 has. It is an RPF learning table and a multicast routing table which the delivery destination router 109 has. It is a figure showing the connection of the RPF interface of the delivery origin router 105 and the delivery destination routers 106-109. It is a figure explaining a multicast tree completion figure. It is a figure explaining the mode of a multicast packet delivery. 6 is a flowchart in which a multicast tree is changed when a logical path between a distribution destination router 105 and a distribution destination 106 goes down. It is a re-registration flowchart of an RPF interface and an RPF neighbor when a logical path is down. 6 is an RPF learning table of a distribution destination router 106; It is a multicast routing table of the distribution origin router 105. FIG. It is a multicast routing table of the distribution destination router 106. FIG. It is a multicast routing table of the distribution destination router. FIG. 3 is a diagram illustrating a multicast tree when a distribution source router 105 and a distribution destination router 106 pass down. It is a flowchart in which the multicast tree is changed when the logical paths of the distribution destination routers 106 and 107 are down. It is an RPF learning table of the distribution destination router 107. It is a multicast routing table of the distribution origin router 105. FIG. It is a multicast routing table of the distribution destination router 106. FIG. It is a multicast routing table of the distribution destination router 107. FIG. It is a flowchart in which the multicast tree is changed when the logical paths of the distribution destination routers 106 and 107 are down.

Hereinafter, examples will be described with reference to the drawings.
In this embodiment, the multicast distribution source router 105 and the routers 106 to 109 have an IP address of RP (Rendezvous Point), and the RPF that is an address of an adjacent router that allows the multicast distribution source router and the distribution destination router to receive the multicast.
Based on the distribution of learning messages of multicast RPF (Reversing Path Forwarding) including neighbor (Reversing Path Forwarding neighbor), multicast distribution group ID, and priority, and learning messages of RPF distributed by routers 106-109 This is a multicast distribution system for determining an RPF.

FIG. 1 is a configuration diagram of a multicast distribution system according to the present embodiment.
The multicast system shown in FIG. 1 is connected to one multicast distribution server 110, multicast distribution source router 105 (hereinafter referred to as distribution source router 105), multicast distribution destination routers 106 to 109, and each router. It is comprised from PC101-104.

  The multicast distribution server 110 is connected to the distribution source router by a logical bus. Further, the distribution source router 105 is connected to each of the routers 106 to 109, which are multicast distribution destinations, via a logical bus, and the routers 106 to 109 are connected to each other via a logical bus. As shown in FIG. 1, a state in which the distribution source router 105 and the routers 106 to 109 are connected like a network via a logical bus is assumed to be a full mesh connection state. The PCs 102 to 104 are connected to the routers 106 to 109 by logical buses, respectively.

  Details of the distribution source router 105 and the multicast distribution destination routers 106 to 109 will be described with reference to FIGS.

  FIG. 2 is a diagram for explaining the configuration of the distribution source router 105. The distribution source router includes a routing control unit 201, a physical interface unit 202, and a storage unit 203, which are connected by signal lines.

  The routing control unit 201 distributes traffic to each router based on a multi-routing table described later. The physical interface unit 202 connects the distribution source router 105 to all the distribution destination routers 106 to 109 and the multicast distribution server 110. The connection between each distribution destination router and the multicast distribution server is confirmed by the logical interfaces 204 to 207 in the physical interface unit.

  In the present embodiment, as shown in FIG. 2, the multicast distribution server 110 and the distribution destination routers 106 to 109 are connected to two different physical interfaces, each having a logical interface, 1: 1 connection, and one-to-many connection. Although connected, other physical interfaces and logical interfaces may be supported.

  The storage unit 203 stores a router confident multicast distribution group ID 712, a priority 713, an RPF learning message distribution table 902, a multicast routing table 1702, and the like, which will be described later.

  In this embodiment, the network in the previous multicast system can communicate with each of the distribution router 105 and the routers 105 to 109 for communication of unicast communication. The IP address of the logical interface 208 connected to the multicast distribution server of the distribution source router 105 is set as the IP address of the RP.

  In this embodiment, the multicast routing protocol uses PIM-SM (Protocol Independent Multicast-Sparse Mode), but is not limited to this, and other multicast routing protocols may be used.

  3 to 5 are diagrams showing the configuration of the destination routers 106 to 109, respectively. The distribution destination routers 106 to 109 are connected to the PCs 101 to 104, respectively, and the physical interface connected to the PC and the physical interface connected to the other (distribution source router and other distribution destination routers) are separated as shown in the figure. Yes. Other configurations are the same as those in FIG.

  Next, tables and the like held by the distribution source router 105 and the distribution destination routers 106 to 109 will be described with reference to FIGS.

  As shown in FIGS. 7 and 8, each of the routers 105 to 109 has a setting table 701, an RPF learning message delivery 702, an RPF learning table 801, and a multicast routing table 802 in the storage unit in each router.

  The setting table 701 includes a multicast distribution group ID 711, a multicast distribution group ID 712, a priority 713, and an interface 714 of the router itself.

  A multicast distribution group ID 712 indicates an ID of a group in which multicast distribution is performed, and is used for selecting an interface 714 to be used by the ID. Further, when an RPF learning message to be described later is distributed to the router, it is also used to select the same group ID as its own multicast group ID. The priority 713 is used for interface selection when there are a plurality of interfaces in the same multicast distribution group ID 712. The interface 714 indicates from which logical interface the distribution is performed. 9 to 13, the smaller the number of the priority 713, the higher the priority, and the larger the number, the lower the priority. However, the present invention is not limited to this, and the reverse case may be used.

  The RPF learning message distribution table 702 includes an RP IP address 721, an RPF neighbor 724, and an interface 725 for distributing an RPF learning message in addition to the contents of the setting table described above. Note that the value of the interface 714 is the interface 725 that delivers the RPF learning message. The IP address 721 of the RP indicates the IP address of the logical interface of the router that is the base point of multicast distribution connected to the multicast distribution server. In this embodiment, the distribution source router 105 is the IP address of the logical interface 208 connected to the multicast distribution server 110. The RPF neighbor 724 is an IP address of the interface 725 that distributes the RPF learning message.

  In this embodiment, since PIM-SM is used for the routing protocol, the IP address of the logical interface of the distribution source router is the IP address of the RP. However, when other protocols are used, , An IP address corresponding to the IP address of the RP of the PIM-SM is used.

  The RPF learning table 801 is created from the RPF learning message distribution table 702. The RPF interface 815 of the RPF learning table 801 is a logical interface of the router that has received the RPF learning message distribution table 702. In other items, the value of the RPF learning message distribution table 702 is entered.

  The multicast routing table 802 includes a multicast distribution server IP address 821, a multicast group 822, an RP IP address 823, an RPF neighbor 824, an RPF interface 825, and a transmission interface 826. The creation of the multicast routing table 802 will be described later.

  FIG. 9 shows a setting table 901 and an RPF learning message distribution table 902 of the distribution source router 105. In this embodiment, the distribution source router 105 is set as shown in FIG. Since the distribution source router 105 is a distribution source of multicast distribution in this embodiment, there is no need to create an RPF learning table, and the multicast distribution group ID of the distribution source router 105 itself is not set. This is not the case when the is set as the distribution source. In this embodiment, the distribution source router 105 does not receive the RPF learning message. Therefore, the multicast routing table 1702 of the distribution source router 105 is created based on the entry that becomes the shortest hop to the multicast distribution server in the unicast routing table of the distribution source router 105. Specifically, the interface logical interface 208 directly connected to the multicast distribution source server enters the RPF interface 825, and the IP address of the distribution source server enters the RPFneighbor 824.

  Similarly, FIG. 10 shows the distribution destination router 106, FIG. 11 shows the distribution destination router 107, FIG. 12 shows the distribution destination router 108, and FIG. 13 shows the setting table and RPF learning message distribution table of the distribution destination router 109.

  In this embodiment, since the distribution destination router 107 and the distribution destination router 109 are routers that only connect to the PC, no setting table or the like is set, and the RPF learning message is not distributed.

  Next, regarding the creation of the RPF learning table when the distribution destination routers 106 to 109 receive the RPF learning message and the registration of the multicast routing table based on the RPF learning table in the present multicast system, the flowchart of FIG. A description will be given by taking 105, the distribution destination router 106, and the distribution destination router 108 as examples.

  When the distribution destination router 106 receives a new RPF learning message from the distribution source router 105 (1601), the information 921 to 927 of the RPF learning distribution table 902 included in the received RPF learning message is stored in the RPF learning table 1801. Registration is performed (1602).

  At this time, in order to select a suitable RPF interface from the information 921 to 927 of the RPF learning distribution table 902 included in the received RPF learning message, the distribution destination router 106 receives the multicast distribution group ID 1011 of its own and received it. With reference to the multicast distribution group ID in the RPF learning distribution table 902, information having a high priority (one having a priority of 1) is selected from the matching information.

  Accordingly, the RPF learning table 1801 of the distribution destination router 106 selects the RPF neighbor selected by the RP IP address 1811, the multicast distribution ID 1812, and the priority 1814, as shown in FIG.

  Similarly, when the RPF learning message is received from the distribution destination router 108, the same processing can be performed, and information on the multicast distribution group ID 1813, the priority 1815, the RPF neighbor, and the RPF interface in the RPF learning table 1801 is selected.

  Next, it is determined whether there are a plurality of IP addresses of the same RP in the IP address 811 (1811) of the RP in the registered RPF learning table 1801 (1603). : No), among the entries newly registered in the RPF learning table 1801, the RPF neighbor and the RPF interface are registered in the multicast routing table 1802 (1603).

  If there are a plurality of entries having the same RP IP address in the RPF learning table 1801 registered in 1602 (1603: Yes), the multicast distribution group ID of the distribution destination router 106 and the multicast of the registered RPF learning message 1801 are registered. The distribution group IDs are compared (1604). If the multicast distribution group IDs are not equal (1604: no), the RPF neighbor and RPF interface of the newly registered entry newly registered in the RPF learning table 1801 are not registered in the multicast routing table entry (1607).

  If the multicast distribution group IDs are equal (1604: Yes), it is determined whether there are a plurality of entries identical to the multicast distribution ID of the distribution destination router 106 (1605). The RPF neighbor and the RPF interface of the entry newly registered in the RPF learning table 1802 are registered in the routing table entry (1608).

  If there are a plurality of entries identical to the multicast distribution ID (1605: Yes), the priority 813 in the RPF learning table 1801 is determined (1606). When the priority is the highest (when the priority number is small. 1606: Yes), the RPF neighbor and RPF interface of the entry newly registered in the RPF learning table 1801 are registered in the multicast routing table entry (1608). In other cases (1606: no), registration is not performed (1607).

  19 to 21 are diagrams showing the RPF learning table and the multicast routing table created by the distribution destination routers 107 to 109 according to the registration flow of FIG. 14 described later.

  Next, creation of a multicast tree used for multicast distribution in this embodiment will be described with reference to FIGS. 14, 15, 22, and 23. FIG. This embodiment is an example, and a multicast tree created by another connection may be used.

  The distribution source router 105 distributes the RPF learning message to the distribution destination router 106 based on the RPF learning message distribution table 902 of the distribution source router 105. In the present embodiment, the RP IP address 921, the multicast distribution group ID 922, the priority 924, and the corresponding RPF neighbor are distributed.

  Based on the RPF learning message received from the distribution source router 105, the distribution destination router 106 updates the RPF learning table according to the flowchart shown in FIG. 16 (1401) and updates the multicast routing table (1402).

  By this RPF learning table update process (1401), the entry 1811, the entry 1812, and the entry 1814 are registered in the RPF learning table 1801 of the distribution destination router 106. Further, the entries 1821 to 1825 of the multicast routing table 1802 of the distribution source router 106 are registered by the multicast routing table update process (1402).

Next, the distribution destination router 108 distributes the RPF learning message to the distribution destination router 106 based on the RPF learning message distribution table 1202.
In this embodiment, the RP IP address 1221, multicast distribution group ID 1222, priority 1223 and the corresponding RPF neighbor are distributed.

  Based on the RPF learning message received from the router 108, the distribution destination router 106 updates the RPF learning table 1403 according to the flow illustrated in FIG. By this RPF learning table update process (1403), the entry 1813 and the entry 1815 are registered in the RPF learning table 1801 of the distribution destination router 106.

  However, as shown in the flow (1604) shown in FIG. 16, since the multicast group ID of the entry added to the RPF learning table 1801 does not match the ID of the distribution destination router 106, the multicast routing table 1802 is updated. Absent.

  Next, the distribution source router 105 distributes the learning message to the distribution destination router 107 based on the RPF learning message distribution table 902. In this embodiment, the RP IP address 921, the multicast distribution group ID 922, the priority 925, and the corresponding RPF neighbor are distributed.

  Based on the RPF learning message received from the distribution source router 105, the distribution destination router 107 similarly performs the update process (1404) for the RPF learning table and the multicast routing table update process (1405) according to the flow shown in FIG. .

  By this RPF learning table update process (1404), an entry 1911, an entry 1912, and an entry 1914 are registered in the RPF learning table 1901 of the distribution destination router 107. By the multicast routing table update processing (1405), entries 1921 to 1925 of the multicast routing table 1902 of the distribution destination router 107 are registered.

  Next, the distribution destination router 106 distributes the RPF learning message to the distribution destination router 107 based on the RPF learning message distribution table 1002. In this embodiment, the RP IP address 1021, the multicast distribution group ID 1022, the priority 1023, and the corresponding RPF neighbor are distributed.

  Based on the RPF learning message received from the distribution destination router 106, the distribution destination router 107 performs update processing (1406) for the RPF learning table and update processing (1407) for the multicast routing table according to the flow shown in FIG.

  By this RPF learning table update process (1406), an entry 1913 is registered in the RPF learning table 1901 of the distribution destination router 107. Also, from the flowchart (1606) of FIG. 16, since the entry registered for update has a higher priority, the multicast routing table update processing (1407) is performed, and the entries 1921 to 1925 in the multicast routing table 1902 of the distribution destination router 107 are Overwritten registration.

  Thereafter, when the RPF learning message is transmitted from the distribution source router 105 or the distribution destination routers 106 to 109, the received distribution destination router performs the same RPF learning table update processing and multicast routing table processing (1408 to 1414). .

  The RPF neighbor and RPF interface of the multicast routing table of the destination routers 106 to 109 are determined by the flow shown in FIG. As a result, a path for the distribution source router 105 and the distribution destination routers 106 to 109 to transmit the multicast participation packets (hereinafter referred to as join packets) of the PCs 101 to 105 to the RP is determined. That is, the RPF neighbor and the RPF interface registered in the multicast routing table of the distribution destination routers 106 to 109 are paths to the RP of the join packet.

  Details of the connection between the RPF neighbor of the distribution destination routers 106 to 107 and the RPF interface are shown in FIG.

  Since the RPF interface of the distribution destination router 107 is the logical interface 1925 and the RPF neighbor is the IP address 1924 of the logical interface 305, the RPF interface of the distribution destination router 107 is connected to the router 106. Similarly, the distribution destination router 106 and the distribution source router 105, the distribution destination router 108 and the distribution source router 105, and the distribution destination router 109 and the distribution destination router 108 are connected.

  Next, the multicast traffic distribution flow after determining the RPF neighbor and RPF interface of the multicast routing table of the distribution destination routers 106 to 109 will be described with reference to FIGS. 15, 17, 18, 19, 20, 21, 23 and 24.

  The PC 101 transmits a join packet for multicast participation to the distribution destination router 106. When receiving the join packet of the PC 101, the distribution destination router 106 performs a multicast routing table update process (1501). The distribution router 106 distributes the join packet of the PC 101 to the distribution source router 105 according to the RPF neighbor 1824 and the RPF interface 1825 of the multicast routing table 1802 of the distribution destination router 106. Forward to. By this multicast routing table update processing (1501), an entry of the transmission interface 1826 is added to the multicast routing table 1802 of the distribution destination router 106.

  When the distribution router 105 receives the join packet of the PC 101, the distribution router 105 performs a multicast routing table update process (1502), and sends the join packet of the PC 101 to the multicast distribution server 110 according to the RPF neighbor 1724 and the RPF interface 1725 of the multicast routing table 1702 of the distribution source router 105. Forward to. By this multicast routing table update processing (1502), an entry of the transmission interface 1727 of the multicast routing table 1702 of the distribution source router 105 is added.

  When the multicast distribution server receives the join packet of the PC 101, the multicast distribution server updates a distribution destination table (not shown) of the multicast distribution server 101 and transmits multicast traffic to the distribution source router 105.

  When receiving the multicast traffic from the multicast distribution server 110, the distribution source router 105 transmits the multicast traffic to the distribution destination router 106 according to the entry of the transmission interface 1727 of the multicast routing table 1702 of the distribution source router 105.

  When receiving the multicast traffic from the distribution source router 105, the distribution destination router 106 transmits the multicast traffic to the PC 101 according to the entry of the transmission interface 1826 of the multicast routing table 1802 of the distribution destination router 106.

  Next, the PC 102 transmits a join packet to the distribution destination router 107. When receiving the join packet of the PC 102, the distribution destination router 107 performs multicast routing table update processing (1503), and sends the join packet of the PC 102 to the distribution destination router 106 in accordance with the RPF neighbor 1924 and the RPF interface 1925 of the multicast routing table 1902 of the distribution destination router 107. Forward to. By this multicast routing table update process (1503), an entry of the transmission interface 1926 of the multicast routing table 1902 of the distribution destination router 107 is added.

  When the destination router 106 receives the join packet of the PC 102, it performs a multicast routing table update process (1504), and sends the join packet of the PC 101 to the source router 105 in accordance with the RPF neighbor 1824 and the RPF interface 1825 of the multicast routing table 1802 of the destination router 106. Forward to. By this multicast routing table update processing (1504), an entry of the transmission interface 1827 in the multicast routing table 1802 of the distribution destination router 106 is added.

  When receiving the join packet transferred from the distribution destination router 106, the distribution source router 105 transfers the join packet to the multicast distribution server 110 according to the multicast routing table 1702. The multicast distribution server 110 that has received the join packet updates a distribution destination table (not shown).

  The distribution destination router 106 transmits the multicast traffic to the distribution destination router 107 according to the entry of the transmission interface 1827 of the multicast routing table 1802 after the multicast routing table update process (1504).

  That is, since multicast traffic to the PC 101 has already been distributed to the distribution destination router 106, it is only necessary to distribute multicast traffic to a new distribution destination (distribution destination router 107).

  When receiving the multicast traffic from the distribution destination router 106, the distribution destination router 107 transmits the multicast traffic to the PC 102 in accordance with the entry of the transmission interface 1926 in the multicast routing table 1902 of the distribution destination router 107.

  Thereafter, the PC 103 receives the multicast traffic via the distribution destination router 108 and the distribution source router 105, and the PC 104 receives the multicast traffic via the distribution destination 109 and the distribution destination 108 by the same procedure.

  FIG. 23 shows a multicast tree of the distribution source router 105 and the distribution destination routers 106 to 109 completed by the flow of FIG. As described above, the multicast distribution server 110, the distribution source router 105, the distribution destination routers 106 to 109, and the PCs 101 to 104, which are multicast distribution destinations, are connected using the logical path as shown in FIG. The multicast tree is completed. A solid line in FIG. 23 indicates a logical path.

FIG. 24 shows an example of a multicast network configuration when the distribution source router 105, the distribution destination routers 106 to 109, and the PCs 101 to 104 are connected by a physical line in the multicast tree.
24, the multicast distribution server 110 and one distribution source router 105 are connected by a physical line, and each of the distribution source router 105 and the distribution destination routers 106 to 109 is physically connected to one layer 2 switch (hereinafter referred to as layer 2 SW 2211). In this example, the PC 101 and the distribution destination router 106, the PC 102 and the distribution destination router 107, the PC 103 and the distribution destination router 108, and the PC 104 and the distribution destination router 109 are connected by a physical line.

  Note that the layer 2 SW 2211 is a switch for transferring a packet. The physical line is a line connected by a physical communication cable such as a LAN cable or an optical fiber. Further, the solid line in FIG. 24 indicates a physical line, and the broken line with an arrow indicates a logical path.

  In the multicast network, multicast traffic is transmitted from the multicast distribution server 110 to the distribution source router 105. The distribution source router 105 transmits the multicast traffic through the layer 2 SW 2211 to the distribution destination router 106 according to the entry of the transmission interface 1727 of the multicast routing table 1702 and to the distribution destination router 108 according to the entry of the transmission interface 1726.

  The distribution destination router 106 transmits multicast traffic to the PC 101 via the layer 2 SW 2211 according to the entry of the transmission interface 1827 of the multicast routing table 1802 and the multicast traffic according to the entry of the transmission interface 1826 of the multicast routing table 1802.

  The distribution destination router 107 transmits the multicast traffic to the PC 102 according to the entry of the transmission interface 1926 of the multicast routing table 1902.

  Similarly, the distribution destination router 108 transmits the multicast traffic to the distribution destination router 109 via the layer 2 SW 2211 according to the entry of the transmission interface 2027 of the multicast routing table 2002 and the multicast traffic according to the entry of the transmission interface 2026 to the PC 103.

  The distribution destination router 109 transmits the multicast traffic to the PC 104 according to the entry of the transmission interface 2126 of the multicast routing table 2102.

  In a conventional multicast network in a mesh virtual network, for example, the distribution source router 105 shown in FIG. 1 includes a logical interface 204 to the distribution destination router 106, a logical interface 205 to the distribution destination router 107, and a logical interface 206 to the distribution destination router 108. The multicast traffic is copied to the four logical interfaces of the logical interface 207 to the distribution destination router 108 and distributed.

  In the multicast network of the present embodiment, when multicast traffic flows as shown in FIG. 24, the distribution source router 105 is connected to the logical interface 204 to the distribution destination router 106 and the distribution destination logical interface 207 to the distribution destination router 108. Since multicast traffic is copied and distributed to two logical interfaces, the multicast network can reduce the number of copies of the source router multicast traffic, design the multicast network topology in advance, and reduce the load on the source router in advance. it can.

  In the present embodiment, an example of a multicast distribution system that not only reduces the load on the distribution source router that stabilizes the topology of the network by preventing frequent rebuilding of the multicast tree, but also can secure a detour path in the event of a failure is illustrated in FIG. 23, FIG. 25 to FIG.

  FIG. 23 is an example of a configuration diagram illustrating an example of a multicast distribution system in the second embodiment. The distribution destination router 105 and the distribution destination routers 106 to 109 are connected by the multicast tree shown in the first embodiment.

  At this time, as shown in FIG. 25, multicast traffic is transmitted from the distribution server 110 via the distribution source router 105 and each router.

  In this embodiment, a description will be given of securing a detour route when the connection between the distribution source router 105 and the distribution destination router 106 is down (logical path down 2501).

  The process of newly registering the RPF neighbor and RPF interface of the multicast routing table when the connection between logical interfaces goes down will be described with reference to FIG.

First, when the logical interface connection is down (2601), the entry of the RPF learning table 801 corresponding to the same RPF interface as the down logical interface is deleted (2602).
When the RPF neighbor 814 and the RPF interface 815 of the entry of the deleted RPF learning table 801 are entries registered in the multicast routing table 802 (2603), the RPF interface 825 and RPF neighbor 824 registered in the multicast routing table 801 are deleted. (2604).

If there is an entry in the RPF learning table 801 having the same RP IP address as the RP IP address 823 of the deleted multicast routing table entry 802, an entry of the RPF learning table 801 is newly added to the multicast routing table 802. The RPF interface 814 and the RPF neighbor 815 are registered (2606). When there are a plurality of entries in the RPF learning table 801, registration is made based on the multicast distribution group ID 812 and the priority 813.

  A flow in which the multicast tree of FIG. 23 is changed when the logical paths of the destination routers 105 and 106 are down will be described with reference to FIG.

  When the logical path between the distribution source router 105 and the distribution destination router goes down (2501), the multicast traffic delivered from the multicast distribution server 110 to the PC 101 via the distribution source router 105 and the distribution destination router 106, and the distribution source router 105, multicast traffic addressed to the PC 102 via the distribution destination routers 106 and 107 is not distributed to the PC 101 and PC 102 (2502).

  The distribution source router 105 performs logical path down detection processing (2504) between the distribution destination router 105 and the one distribution destination router 107 when the logical path is down (2501), and the multicast routing table is updated according to the flow shown in FIG. Update processing (2506) is performed.

  The logical path down detection (2504) means that the distribution source router 105 monitors the distribution destination router 106, and the distribution destination router 106 detects the distribution source router 105 by performing polling monitoring. Although the down detection means is polling monitoring, other detection means may be used.

  In the multicast routing table update processing 2506, the entry 1727 is deleted from the transmission interface 826 that is the entry of the multicast routing table 1702 shown in FIG. 17, and only the transmission interface 1726 that is the entry of the multicast routing table 2802 shown in FIG. It is processing to.

  The distribution destination router 106 performs detection processing (2503) when the logical path of the distribution destination routers 105 and 107 is detected when the logical path is down (2501), and updates the RPF learning processing table according to the flow shown in FIG. (2505) is performed, and a multicast routing table update process (2507) is performed.

  In the update process (2505) of the RPF learning table, the entry 1814 related to the distribution destination 105 whose logical path is down is deleted from the priority 813, the RPF neighbor 814, and the RPF interface 815 which are the entries of the RPF learning table 1801 shown in FIG. 29, the RPF learning table 1801 has only the entry 1815 for the RPF neighbor 814 and the RPF interface 815.

  In the multicast routing table update process (2507), the entry 1823 and the entry 1824 are deleted from the RPFneighbor 824 which is the entry of the multicast routing table 1802 shown in FIG. Are newly registered in the RPFneighbor 824 of the entry of the multicast routing table 2902 shown in FIG. 28 and the entry 2922 of the RPF interface 825.

  Through the multicast routing table update process (2507), the abandonment destination router 106 transmits join to the distribution destination router 108. When receiving the join packet from the distribution destination router 106, the distribution destination router 108 performs a multicast routing table update process (2508), and adds an entry 3021 to the transmission interface 826 that is an entry of the multicast routing table 3002 shown in FIG.

  When the multicast routing table update process (2507) is completed, the multicast traffic is transmitted from the multicast distribution server 110 to the PC 101 via the distribution source router 105 and the distribution destination router 108, and via the distribution source router 105 and the distribution destination routers 108 and 107. Is delivered to the PC 102.

  In this way, even when a failure occurs in the logical path during multicast traffic distribution, as shown in the present embodiment, the RPF learning table and the multicast routing table are updated to frequently reconstruct the multicast tree. It is possible to create a detour while reducing the load on the distribution source router that stabilizes the network topology in advance.

  Next, a modification of the present embodiment will be described with reference to FIG. When the flow for changing the multicast tree in FIG. 23 is completed, the multicast distribution server 110, the distribution source router 105 connected to the multicast distribution server 110 by a logical path, and the logical path to the distribution source router 105 shown in FIG. Distribution destination router 108 connected using the distribution destination router 108, distribution destination router 106 connected using the logical path, distribution destination router 107 connected to the distribution destination router 106 through the logical path, and distribution destination router 108, a destination router 109 and a PC 101, a destination router 107 and a PC 102, a destination router 107 and a PC 102, a destination router 108 and a PC 103, and a destination router 109 and a PC 104 connected by a logical path. The tree is completed.

  A flow in which the multicast tree of FIG. 23 is changed when the logical paths of the destination routers 106 and 107 are down will be described with reference to FIG.

  When the logical path between the distribution source router 105 and the distribution destination router 106 goes down 3201, the multicast traffic addressed to the PC 102 via the distribution source router 105 and the distribution destination router 106 distributed from the multicast distribution server 110 is distributed to the PC 102. It disappears (3202).

The distribution destination router 106 detects the logical path down of the distribution destination routers 106 and 107 by the logical path down 3201 (3204), and updates the multicast routing table (3206) by the flow shown in FIG. )I do.
In the multicast routing table update process (3206), the entry 1827 is deleted from the transmission interface 826 that is the entry of the multicast routing table 1802 shown in FIG. 18, and the transmission interface that is the entry of the multicast routing table 3502 shown in FIG. 826 is only an entry 1726.

  The distribution destination router 107 performs detection processing (3203) when the logical path of the distribution destination routers 106 and 107 is detected when the logical path is down (3201), and updates the RPF learning table according to the flow shown in FIG. 3205), and a multicast routing table update process (3207) is performed. In the RPF learning table update process (3205), the entry 1913 is deleted from the priority 813, the RPF neighbor 814, and the RPF interface 815 which are the entries of the RPF learning table (1901) shown in FIG. 19, and the RPF learning shown in FIG. The entries of the table 1901 are the entries of the RPF neighbor 814, and the entries of the RPF interface 815 are only 1914.

  In the multicast routing table update process (3207), the entries 1924 and 1925 are deleted from the RPFneighbor 824 which is the entry of the multicast routing table 1902 shown in FIG. Are newly registered in the RPF neighbor 824 of the entry of the multicast routing table 3602 shown in FIG. 36 and the entry 3622 of the RPF interface 825.

  Through the multicast routing table update process (3207), the distribution destination router 106 transmits join to the distribution source router 105. When the distribution source router 105 receives the join packet from the distribution destination router 106, it performs multicast routing table update processing (3208), and adds an entry 3421 to the transmission interface 826 that is an entry of the multicast routing table 3402 shown in FIG.

When the multicast routing table update process (3207) is completed, the multicast traffic is distributed from the multicast distribution server 110 to the PC 102 via the distribution source router 105.
When the flow for changing the multicast tree in FIG. 32 is completed, the multicast distribution server 110, the distribution source router 105 connected to the multicast distribution server 110 by a logical path, and the logical path to the distribution source router 105 shown in FIG. Distribution destination routers 105 to 108 connected by using, distribution destination router 109 connected to the distribution destination router 108 through a logical path, and PCs 101 to 104 connected through the distribution destination routers 106 to 109 logical path, A multicast tree is completed.

  In this way, even when a failure occurs in the logical path between the distribution destination routers during the distribution of the multicast traffic, the multicast tree is updated by updating the RPF learning table and the multicast routing table as shown in the present modification. It is possible to create a detour while reducing the load of the distribution source router that prevents frequent reconfigurations and stabilizes the network topology.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. It is also possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or add the configuration of another embodiment. In addition, it is possible to add, delete, and replace other configurations for a part of the configuration of the embodiment.

  In addition, each said structure, function, etc. interpret and run the program which a processor implement | achieves each function. Information such as programs and tables for realizing each function can be stored in a storage medium such as a memory or a hard disk.

101-104 User terminal 105 Distribution source router 106-109 Distribution destination router 110 Multicast distribution server 201 Routing control unit 202 Physical interface unit 203 Storage unit 204-208 Logical interface unit 301 Routing control unit 302 Physical interface unit 303 Storage units 304-308 Logical interface unit 401 Routing control unit 402 Physical interface unit 403 Storage units 404 to 408 Logical interface unit 501 Routing control unit 502 Physical interface unit 503 Storage units 504 to 508 Logical interface unit 601 Routing control unit 602 Physical interface unit 603 Storage unit 604 to 608 Logical interface unit 701 Setting table 70 of distribution source router 105 and router distribution destinations 106 to 109 2 Message distribution table for RPF learning 711 Multicast distribution group ID of router
712 Multicast group delivery ID entry 713 Priority entry 714 RPF learning message entry 721 RP IP address entry 722 Multicast group delivery ID entry 723 Priority entry 724 RPFneighbor entry 725 For RPF learning 801 entry of interface for delivering message RPF learning table 802 multicast routing table 811 entry for RP IP address 812 entry for multicast group delivery ID 813 entry for priority 814 entry for RPF neighbor 815 entry for RPF interface 821 IP address for multicast delivery server Entry 822 of multicast group I Entry 2211 Layer 2SW apparatus entry 826 transmission interface entry 825 RPF interface entry 824 RPFneighbor the IP address of the address of the entry 823 RP

Claims (11)

A multicast distribution system comprising a server for distributing multicast traffic, a distribution source router connected to the server, a plurality of distribution destination routers connected to the distribution source router, and the plurality of distribution destination routers,
The distribution source router and the plurality of distribution destination routers are respectively connected to form a mesh-structured network,
At least one of the distribution source router and the plurality of distribution destination routers is an interface that distributes the multicast traffic to an address of an adjacent distribution destination router that permits reception of the multicast traffic and the adjacent distribution destination router. Including a learning message including: and transmitting the learning message to the adjacent destination router;
The adjacent distribution destination router that has received the learning message selects an interface to which the multicast traffic is distributed based on the learning message, and creates a multicast distribution tree. The learning message is used when there are a plurality of multicast distribution group IDs for identifying an address serving as a base point of multicast distribution, a multicast distribution group ID for identifying a group to which multicast traffic distribution is performed, and the multicast distribution group ID. Priority to select an interface for delivering traffic,
The multicast distribution system according to claim 1, wherein the adjacent distribution destination router that has received the learning message creates a multicast routing table used for distribution of multicast traffic based on the learning message.   The multicast distribution system according to claim 2, wherein the routing table is created or updated based on the multicast group ID of the distribution destination router when the learning message is received.   The multicast distribution system according to claim 3, wherein the routing table is created or updated based on the priority.   When the distribution source router or the plurality of distribution destination routers detect that the interface for distributing the multicast traffic in the routing table cannot be used, the interface deletes the interface from the multicast routing table and receives the received learning message 3. The multicast according to claim 2, wherein a message requesting distribution of multicast traffic is transmitted to another distribution destination router or distribution source router according to the above, a new multicast distribution tree is created, and distribution of the multicast traffic is continued. Distribution system. A router for delivering multicast traffic,
Priority for selecting an interface that distributes the multicast traffic to be used to other routers when there are a plurality of multicast distribution group IDs that identify a group to which multicast traffic distribution is performed and the same multicast distribution group ID And an interface for delivering multicast traffic to other neighboring routers,
Based on the multicast distribution group ID, the priority, and the interface, create a learning message necessary for creating a route used for multicast traffic distribution,
A router that creates a route to be used for multicast traffic distribution by transmitting / receiving the learning message to / from another adjacent router.   The router according to claim 6, wherein an interface that has received the learning message is used to create a route used for distributing the multicast traffic. When it is detected that the interface that received the learning message cannot be used,
8. The router according to claim 7, wherein a message requesting distribution of multicast traffic is transmitted to an adjacent router or a multicast traffic distribution source router based on the learning message. A multicast distribution method in a multicast distribution system comprising a server for distributing multicast traffic, a distribution source router connected to the server, a plurality of distribution destination routers connected to the distribution source router, and the plurality of distribution destination routers. ,
The distribution source router creates a learning message from an address of an adjacent distribution destination router that permits reception of the multicast traffic in a storage unit and information of an interface that distributes the multicast traffic to the adjacent distribution destination router; Sending the learning message to the adjacent destination router;
The plurality of distribution destination routers creates a learning message from an address of an adjacent distribution destination router that permits reception of the multicast traffic from a storage unit and information on an interface that distributes the multicast traffic to the adjacent distribution destination router. Transmitting the learning message to the adjacent distribution destination router; and selecting an interface to which the multicast traffic is distributed based on the learning message and creating a multicast distribution tree. Multicast delivery method. The learning message is used when there are a plurality of multicast distribution group IDs for identifying an address serving as a base point of multicast distribution, a multicast distribution group ID for identifying a group to which multicast traffic distribution is performed, and the multicast distribution group ID. Priority to select an interface for delivering traffic,
The multicast distribution method according to claim 9, wherein the distribution destination router that has received the learning message includes a step of creating a multicast routing table used for distribution of multicast traffic based on the learning message.   The distribution source router or the plurality of distribution destination routers detects whether or not an interface that distributes the multicast traffic in the routing table is usable, deletes the interface from the multicast routing table, and the received learning 10. The multicast distribution method according to claim 9, further comprising the steps of: transmitting a message requesting distribution of multicast traffic to another distribution destination router or distribution source router according to the message; and creating a new multicast distribution tree.

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