TRANSMISSION DEVICE, TRANSMISSION SYSTEM, AND TRANSMISSION METHOD

Abstract

To suppress the occurrence of bandwidth congestion.SOLUTION: Control units 1a and 2a mutually transmit pieces of address information ad1 and ad2 for communication between transmission devices 1 and 2, and share the pieces of address information ad1 and ad2. When the control unit 1a detects a generation trigger of a path p0, the control unit 1a determines whether a communication policy for generating the path p0 in a relay network N1 and performing stream distribution is satisfied on the basis of policy information pc in a storage unit 1b. When the communication policy registered in the policy information pc is satisfied, the control unit 1a transmits a control signal indicating the determination result to the transmission device 2. Upon receiving the control signal, the control unit 2a determines whether the communication policy is satisfied on the basis of the policy information pc in the storage unit 2b. When the policy information pc is satisfied in both transmission devices 1 and 2, the control units 1a and 2a control path generation to generate the path p0 in the relay network N1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a transmission device, a transmission system, and a transmission method. [Background technology]

[0002] In recent years, networks connecting broadcast-related media nodes are increasingly being made IP (Internet Protocol)-based, and the use of technologies such as IP multicast and IGMP (Internet Group Management Protocol) for media distribution is progressing.

[0003] IP multicast is a technology for simultaneously sending data to multiple nodes on an IP network, while IGMP is a protocol for users to notify routers when they want to join or leave a multicast group.

[0004] These technologies make it possible to realize, for example, a one-to-many IP multicast distribution service from one transmitting node of a camera / microphone sound source system to multiple receiving nodes. Related technologies include, for example, a technology that generates connection information on the network configuration of a multicast tree and sets up or deletes paths corresponding to reservation times based on the connection information. Also, a technology has been proposed that calculates an IP multicast route for an IP multicast group that has a sending node and a receiving node, and forwards the IP multicast along the calculated route. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-049986 A [Patent Document 2] International Publication No. 2014 / 199924 Summary of the Invention [Problem to be solved by the invention]

[0006] Multicast routing protocols such as Protocol-Independent Multicast (PIM) operate on networks that transmit IP multicast. However, in the past, for example, when IGMP joins and leaves frequently, routers would become congested due to the load of calculating the delivery path of the routing protocol, and IP multicast relay links would fluctuate, causing bandwidth congestion.

[0007] In one aspect, the present invention has an object to provide a transmission device, a transmission system, and a transmission method that suppress the occurrence of bandwidth congestion. [Means for solving the problem]

[0008] In order to solve the above problem, a transmission device is provided. Streaming The transmission device has a memory unit that stores address information for communicating with an opposing device via a relay network and policy information in which a communication policy is set when streaming distribution is performed in the relay network, and a control unit that holds the address information together with the opposing device and generates a path to the relay network based on the address information and policy information when a generation trigger for generating a path for communication is detected. The policy information also includes identification information of the transmission device, identification information of a multicast group connected to an access network subordinate to the transmission device and performing streaming distribution, identification information of a terminal connected to the access network and performing streaming distribution, permission information indicating whether or not to permit the generation of a path, and status information indicating the connection status of the path.

[0009] In order to solve the above problem, a transmission system that executes control similar to that of the above transmission device is provided. Furthermore, in order to solve the above problems, a transmission method is provided that executes control similar to that of the above transmission device. Effect of the Invention

[0010] According to one aspect, it is possible to suppress the occurrence of bandwidth congestion. [Brief description of the drawings]

[0011] [Figure 1]FIG. 1 is a diagram illustrating an example of a transmission system according to a first embodiment. [Diagram 2] FIG. 1 illustrates an example of a transmission system according to a second embodiment; [Diagram 3] FIG. 1 is a diagram illustrating an example of traffic flow in a transmission system. [Figure 4] FIG. 2 illustrates an example of functional blocks of a transmission device. [Diagram 5] FIG. 2 illustrates an example of a hardware configuration of a transmission device. [Figure 6] FIG. 11 illustrates an example of an address information table. [Figure 7] FIG. 11 illustrates an example of an address information table. [Figure 8] FIG. 11 illustrates an example of an address information table. [Figure 9] FIG. 11 illustrates an example of a multicast information table. [Figure 10] FIG. 11 illustrates an example of a policy information table. [Figure 11] FIG. 11 is a diagram showing an example of an operation sequence in which an IGMP trigger occurs and IP multicast is performed. [Figure 12] 13 is a flowchart showing an example of a policy control operation. [Figure 13] 13 is a flowchart showing an example of a policy control operation. [Figure 14] FIG. 11 is a diagram illustrating an example of an operation sequence of pre-path generation. [Figure 15] FIG. 11 is a diagram illustrating an example of an operation sequence of path control when a failure occurs. [Figure 16] 11 is a flowchart showing an example of an operation from receiving a failure message to blocking or re-establishing a path. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] The present embodiment will be described below with reference to the drawings. [First embodiment] 1 is a diagram for explaining an example of a transmission system according to a first embodiment. The transmission system 1-1 includes transmission devices 1 and 2, which are connected via a relay network N1. The transmission device 1 includes a control unit 1a (first control unit) and a storage unit 1b (first storage unit), and the transmission device 2 includes a control unit 2a (second control unit) and a storage unit 2b (second storage unit).

[0013] In the transmission device 1, the storage unit 1b stores address information ad1, ad2 for communication via the relay network N1, and policy information pc in which a communication policy (policy) for performing stream distribution in the relay network N1 is set.

[0014] The control unit 1a holds address information ad1, ad2 together with the transmission device 2, and when a trigger for generating a path p0 is detected, the control unit 1a generates a path p0 for the relay network N1 based on the address information ad1, ad2 and policy information pc, and controls the relay path for stream distribution.

[0015] In the transmission device 2, the storage unit 2b stores address information ad1, ad2 and policy information pc. The control unit 2a holds the address information ad1, ad2 together with the transmission device 1, and generates a path p0 for the relay network N1 based on the address information ad1, ad2 and the policy information pc to control relay of the stream distribution. The functions of the control units 1a and 2a are realized by processors (not shown) included in the transmission devices 1 and 2 executing predetermined programs.

[0016] The operation will be explained using the example of FIG. [Step S1] The control unit 1a transmits address information ad1 to the transmission device 2, and the control unit 2a transmits address information ad2 to the transmission device 1, so that the transmission devices 1 and 2 share the address information ad1 and ad2 for communication therebetween.

[0017] [Step S2] The control unit 1a detects a generation trigger for the path p0. [Step S3] Based on the policy information pc in the storage unit 1b, the control unit 1a determines whether or not the communication policy is satisfied when the path p0 is generated in the relay network N1 and stream distribution is performed.

[0018] [Step S4] If the communication policy registered in the policy information pc is satisfied, the control unit 1a transmits a control signal to that effect to the transmission device 2. [Step S5] Upon receiving the control signal, the control unit 2a judges, based on the policy information pc in the storage unit 2b, whether or not the communication policy for generating the path p0 in the relay network N1 and performing stream distribution is satisfied.

[0019] [Step S6] If the communication policies registered in the policy information pc in both the transmission devices 1 and 2 are satisfied, the control units 1a and 2a generate a path p0 to the transit network N1. In this way, in the transmission system 1-1, when a path generation trigger is detected after address information is shared between transmission devices, a path based on policy information is generated for the relay network between the transmission devices, and relay of the stream distribution is controlled.

[0020] As a result, paths based on the communication policy are generated sequentially at the transmission devices at the source and destination of the stream, so that even in cases where there is frequent joining / leaving of stream distribution, unexpected bandwidth fluctuations do not occur and bandwidth congestion can be suppressed.

[0021] [Second embodiment] Next, a second embodiment in which the function of the transmission system 1-1 shown in Fig. 1 is applied to stream distribution by IP multicast will be described in detail below. In the following, the path may be called an LSP (Label Switched Path). In the following, an LSP by P2MP RSVP-TE (Point to Multi Point Resource Reservation Protocol-Traffic Engineering) will be used for the explanation, but it is also possible to use a method that uses multiple P2P paths (duplicating multicast traffic at the transmission device on the sending side), such as an LSP by P2P RSVP-TE.

[0022] In addition, the following application of IGMPv3 and IPv4 group IDs and source IDs to IPv4 multicast can also be implemented for IPv6 multicast by replacing them with MLDv2 (Multicast Listener Discovery version 2, a type of ICMPv6) and IPv6 group IDs and source IDs.

[0023] <System configuration> 2 is a diagram showing an example of a transmission system according to the second embodiment. The transmission system 1-2 includes transmission devices 10-1 and 10-2. The transmission device 10-2 is a transmitting device, and the transmission device 10-1 is a receiving device. The transmission devices 10-1 and 10-2 each have both a transmitting function and a receiving function.

[0024] A transmitting / receiving station 3 is located on the user network (corresponding to an access network under the device) side of the transmission device 10-2, and nodes 31 and 32 in the transmitting / receiving station 3 are connected to the transmission device 10-2. The nodes 31 and 32 are, for example, a photographing device (camera) or a sound collecting device (microphone).

[0025] A transmitting / receiving station 4 is located on the user network side of the transmission device 10-1, and terminals (monitors, etc.) 41 and 42 in the transmitting / receiving station 4 are connected to the transmitting / receiving station 4. In addition, an MPLS (Multi-Protocol Label Switching) / IP network n1 is connected to the relay network sides of the transmission devices 10-1 and 10-2.

[0026] The transmission devices 10-1 and 10-2 respectively have the functions of the transmission devices 1 and 2 shown in Fig. 1. In addition, the transmission devices 10-1 and 10-2 have a P2MP RSVP-TE head-end function (a function for transmitting and terminating video, audio, data, etc.) and a function for identifying the accessed traffic by policy information.

[0027] RSVP-TE is a signaling protocol for reserving resources and setting up paths, and is an extension of RSVP that incorporates elements of traffic engineering into RSVP.

[0028] Moreover, the transmission devices 10-1 and 10-2 have a function of establishing a multicast path of P2MP LSP to any transmission device. Furthermore, the transmission device 10-1 has a function of analyzing an IGMPv3 signal (generation trigger) between the transmission device 10-1 and the transmitting / receiving station 4, monitoring the presence of a terminal in the transmitting / receiving station 4 (hereinafter, the terminal of the transmitting / receiving station may be called a user terminal), and outputting a control signal based on the IGMPv3 notification to a distribution source requested by the user terminal.

[0029] 2, in the notation {Sa, Ga} of the nodes 31 and 32, Sa means that the ID (source ID) of the node is Sa, and Ga means that the multicast group ID to which the node belongs, which is the multicast source, is Ga.

[0030] FIG. 3 is a diagram showing an example of a traffic flow in a transmission system. [Step S11] The transmission device 10-1 analyzes the IGMPv3 sent from the user terminal and detects the source ID and multicast group ID of the node that sends the information that the user terminal wants to receive. The transmission device 10-1 then transmits a request to the transmission device 10-2 to establish an LSP for receiving the information sent from the detected node.

[0031] [Step S12] At UNI (User Network Interface) #1a, the transmission device 10-2 maps the source ID and multicast group ID of node {S1, G1} to the service information (main signal) output from node {S1, G1} to generate multicast information.

[0032] This multicast information is encapsulated and transmitted from the network node interface (NNI) #2 through a tunnel (eg, a source to leaf (S2L) sub-LSP5a) in the P2MP LSP5 toward the transmission device 10-1.

[0033] [Step S13] At UNI#1b, the transmission device 10-2 generates multicast information by mapping the source ID and multicast group ID of node {S2, G2} with the service information output from node {S2, G2}. This multicast information is encapsulated and transmitted from NNI#2 to the transmission device 10-1 through a tunnel (e.g., S2L sub-LSP5b) in P2MP LSP5.

[0034] [Step S14] The S2L sub-LSP5a is connected to the NNI#3 of the transmission device 10-1, and information transmitted through the S2L sub-LSP5a is sent to the corresponding user terminal via the UNI#4a.

[0035] [Step S15] The S2L sub-LSP5b is connected to the NNI#3 of the transmission device 10-1, and information transmitted through the S2L sub-LSP5b is sent to the corresponding user terminal via the UNI#4b.

[0036] <Function block> 4 is a diagram showing an example of functional blocks of a transmission device. In the following, the transmission devices 10-1 and 10-2 may be collectively referred to as the transmission device 10. The transmission device 10 includes a control unit 11, a storage unit 12, and a communication unit 13.

[0037] 4, "a" in the reference numerals indicates a functional block that controls the UNI block side, and "b" in the reference numerals indicates a functional block that controls the NNI block side. Also, the storage unit 12 is used in common for controlling the UNI block and the NNI block.

[0038] Control unit 11 includes, as functional blocks for controlling the UNI block side, a receiving unit 11a1, a transmitting unit 11a2, an IGMP / ICMP (Internet Control Message Protocol) processing unit 11a3, a policy management unit 11a4, and a time management unit 11a5.

[0039] Moreover, the control unit 11 includes, as functional blocks for controlling the NNI block side, a receiving unit 11b1, a transmitting unit 11b2, an RSVP processing unit 11b3, a policy management unit 11b4, a time management unit 11b5, and a path management unit 11b6.

[0040] Furthermore, the communication unit 13 includes a communication IF (interface) unit 13a1, a demultiplexing / multiplexing unit 13a2, and a filter unit 13a3 as functional blocks that control the UNI block side. The communication unit 13 also includes a communication IF unit 13b1, a demultiplexing / multiplexing unit 13b2, and an MPLS encapsulation / decapsulation unit 13b3 as functional blocks that control the NNI block side. The communication unit 13 also includes a switch unit sw that performs switching between the UNI block and the NNI block.

[0041] The operation of each functional block will be described. The communication IF unit 13a1 is connected to the user network ne1, and is an interface for communicating with the transmitting / receiving station via the UNI (transmitting / receiving station side). The demultiplexing / multiplexing unit 13a2 separates control signals (IGMP, ICMPv6) from the UNI (transmitting / receiving station side) from main signals such as IP multicast. The demultiplexing / multiplexing unit 13a2 also multiplexes the control signals output from the UNI block to the user network ne1 and the main signals input from the NNI block, and outputs the multiplexed signal in the UNI direction.

[0042] The filter unit 13a3, in accordance with a communication policy (hereinafter simply referred to as policy), transparently transfers the IP multicast stream received from the UNI to the NNI block if it is to be relayed, or discards it if it is to be cut off without being relayed.

[0043] The receiver 11a1 receives a control signal from the UNI separated by the demultiplexer / multiplexer 13a2 and outputs it to the IGMP / ICMP processor 11a3. The transmitter 11a2 receives IGMP / ICMP transmission from the IGMP / ICMP processor 11a3 toward the UNI and sends it to the demultiplexer / multiplexer 13a2.

[0044] The IGMP / ICMP processing unit 11a3 processes IGMPv3 frames and ICMPv6 frames (RA (Router Advertise) processing). Policy management unit 11a4 manages policy information and executes policy control shown in Fig. 12. Policy management unit 11a4 also communicates with policy management unit 11b4.

[0045] The time management unit 11a5 holds the device time (for example, the time to which the device is synchronized using NTP (Network Time Protocol) or PTP (Precision Time Protocol)) and provides the time information to the policy management unit 11a4. The switch unit sw relays traffic from the UNI block to the NNI block, or from the NNI block to the UNI block.

[0046] The communication IF unit 13b1 connects to the carrier relay network ne2 and performs an NNI communication interface with the relay network side. The demultiplexing / multiplexing unit 13b2 demultiplexes a control signal (RSVP) from the NNI (relay network) and a main signal (MPLS), multiplexes the control signal transmitted from the NNI block with the main signal input from the UNI block, and outputs the multiplexed signal in the NNI direction.

[0047] The MPLS encapsulation / decapsulation unit 13b3 removes (decapsulates) the MPLS header input from the NNI direction, and adds (encapsulates) the MPLS header to be output to the NNI direction. The reception unit 11b1 receives the control signal from the NNI separated by the separation / multiplexing unit 13b2, and passes it to the RSVP processing unit 11b3.

[0048] The transmitter 11b2 receives RSVP transmission in the NNI direction from the RSVP processor 11b3 and sends it to the demultiplexer / multiplexer 13b2. The RSVP processor 11b3 processes P2MP RSVP-TE frames. Policy management unit 11b4 manages policy information and executes policy control in Fig. 13 described below and path control when a failure occurs in Fig. 16 described below. Policy management unit 11b4 also relays requests from policy management unit 11a4 of the UNI block and transmits them to path management unit 11b6.

[0049] The time management section 11b5 holds the device time and provides the time information to the policy management section 11b4. The path management section 11b6 performs transmission and reception processing of control signals, and notifies the policy management section 11b4 of the reception of a control signal.

[0050] In addition, the path management unit 11b6 performs P2MP LSP generation / deletion / route change operations on the RSVP processing unit 11b3 in response to a request from the policy management unit 11b4. Furthermore, the path management unit 11b6 performs LSP normality monitoring (activity monitoring), and performs LSP recovery processing when the LSP is unintentionally cut off due to a fault in the relay network, etc. The storage unit 12 stores each table information shown in Fig. 6 to Fig. 10 described later.

[0051] <Hardware configuration> 5 is a diagram showing an example of a hardware configuration of a transmission device 10. The transmission device 10 is entirely controlled by a processor (computer) 100. The processor 100 realizes part of the functions of the control unit 11 and the communication unit 13.

[0052] The processor 100 is connected to a memory 101 , an input / output interface 102 , and a network interface 104 via a bus 103 . The processor 100 may be a multiprocessor. The processor 100 may be, for example, a central processing unit (CPU), a field programmable gate array (FPGA), a micro processing unit (MPU), a digital signal processor (DSP), an application specific integrated circuit (ASIC), or a programmable logic device (PLD). The processor 100 may also be a combination of two or more elements of a CPU, an FPGA, an MPU, a DSP, an ASIC, or a PLD.

[0053] The memory 101 realizes the function of the storage unit 12 and is used as a main storage device of the transmission device 10. The memory 101 temporarily stores at least a part of an OS (Operating System) program and application programs to be executed by the processor 100. The memory 101 also stores various data required for processing by the processor 100.

[0054] The memory 101 is also used as an auxiliary storage device of the transmission device 10, and stores an OS program, application programs, and various data. The memory 101 may include, as an auxiliary storage device, a semiconductor storage device such as a flash memory or an SSD (Solid State Drive), or a magnetic recording medium such as an HDD (Hard Disk Drive).

[0055] An input / output interface 102 and a network interface 104 may be connected to the bus 103. The input / output interface 102 can be connected to an information input device such as a keyboard or a mouse, and transmits signals sent from the information input device to the processor 100.

[0056] The input / output interface 102 also functions as a communication interface for connecting peripheral devices. For example, the input / output interface 102 can connect an optical drive device that uses laser light or the like to read data recorded on an optical disc. Optical discs include Blu-ray Disc (registered trademark), CD-ROM (Compact Disc Read Only Memory), CD-R (Recordable) / RW (Rewritable), etc.

[0057] Furthermore, the input / output interface 102 can connect to a memory device or a memory reader / writer. The memory device is a recording medium equipped with a function for communicating with the input / output interface 102. The memory reader / writer is a device for writing data to a memory card or reading data from a memory card. The memory card is a card-type recording medium.

[0058] The network interface 104 realizes the function of the communication unit 13, and controls the network interface by connecting to a network. For example, a NIC (Network Interface Card) or a wireless LAN (Local Area Network) card can be used as the network interface 104. Data received by the network interface 104 is output to the memory 101 or the processor 100.

[0059] The above hardware configuration can realize the processing functions of the transmission device 10. For example, the transmission device 10 can perform the processing of the present invention by causing the processors 100 to execute predetermined programs.

[0060] The transmission device 10 realizes the processing functions of the present invention by, for example, executing a program recorded on a computer-readable recording medium. The program describing the processing contents to be executed by the transmission device 10 can be recorded on various recording media.

[0061] For example, the program to be executed by the transmission device 10 may be stored in an auxiliary storage device. The processor 100 loads at least a part of the program in the auxiliary storage device into the main storage device and executes the program.

[0062] The program may also be recorded on a portable recording medium such as an optical disk, a memory device, or a memory card. The program stored on the portable recording medium is executable after being installed in an auxiliary storage device under the control of the processor 100. The processor 100 may also directly read out and execute the program from the portable recording medium.

[0063] Next, the table information stored in the storage unit 12 will be described with reference to Fig. 6 to Fig. 10. Fig. 6 is a diagram showing an example of an address information table. Items registered in the address information table T1 include, for example, an NNI router ID (router ID), which is an IP address for uniquely identifying a device, a network number, an IPv4 network address, an IPv6 prefix, a group ID, a source ID, and version information.

[0064] The NNI router ID includes the network number, which includes the IPv4 network address, IPv6 prefix, group ID, source ID, and version information. For a group ID, the source ID can be given information of 0 or more (0 is no source ID).

[0065] Also, the group ID or source ID may be configured as a table that can hold one or more. Such a table configuration can use a list format (group IDs or source IDs are arranged in a list) or an address mask format (group ID or source ID is expressed as a range set of a bit mask indicating the valid range or the valid prefix length from the beginning of the ID).

[0066] FIG. 7 shows an example of an address information table T1a having a table configuration in list format, and FIG. 8 shows an example of an address information table T1b having a table configuration in address mask format.

[0067] On the other hand, the NNI router ID is the loopback IP address (IPv4 or IPv6 address) of the NNI that identifies the transmission device. The network number is an identifier of the user network. The IPv4 network address is the network address to which the UNI (subordinate IF) of the transmission device belongs, and the IPv4 / netmask length is set.

[0068] The IPv6 prefix is ​​the IPv6 prefix to which the IF belongs, and the IPv6 prefix / prefix length is set (learned when RA is received). The group ID indicates which policy the multicast group ID matches (IPv4 or IPv6 group ID).

[0069] The version information is incremented when any change occurs in the information registered in the table, and indicates the latest state. Note that the network number and each piece of information included in the network number correspond to address information of the access network (network of transmitting and receiving stations) under the control of the transmission device 10.

[0070] 9 is a diagram showing an example of a multicast information table. Items registered in the multicast information table T2 include, for example, a group ID (G), a network number, a source ID (S), a tunnel ID, an LSP ID, a destination node, an S2L sub-LSP ID, and a user IP address (L). This information is used when establishing a path in a transit network.

[0071] The source ID (S) includes a tunnel ID, which includes an LSP ID, which includes a destination node, an S2L ID, and a user IP address (L). The group ID (G) is the multicast group ID (the group ID used to identify which group's information is to be transmitted over which LSP). The network number is the identifier of the user network. The source ID is the identifier of the sender (IPv4 or IPv6 address). One entry consists of the group ID (G) + network number + source ID.

[0072] The tunnel ID, LSP ID, and S2L sub-LSP ID are the IDs of the three-layered path defined in the P2MP LSP standard. The tunnel ID is assigned at the time of entry, and the LSP ID and S2L sub-LSP ID are assigned at the time of user registration.

[0073] The destination node is the loopback IP address of the NNI of the destination transmission device of the LSP (IPv4 address). The user IP address (L) is the address of the user terminal (IPv4 or IPv6 address).

[0074] 10 is a diagram showing an example of a policy information table. The policy information table T3 is set for each UNI of the transmission device 10. Items registered in the policy information table T3 include, for example, a group ID (G), a source ID (S), a user ID (L), permit (permission information), a status, and an option (examples of the setting values ​​are omitted).

[0075] Note that the group ID includes the source ID, and the source ID includes the user ID, permit, status, and options. The options include the time zone (time information), pre-path generation, and paths p1 and p2 (in this example, there are registrations for two paths, but any number of registrations is possible).

[0076] The group ID is the group ID of the source that requests service information and is a multicast address. The source ID is the source ID (IP address). The user ID is the IP address of the requester (user IP address (or Don't care)). The permit is permission information indicating permission / non-permission. That is, it is information indicating which user ID is permitted to generate a path for which source ID of which group ID.

[0077] The status is information indicating any one of unconnected, connecting, and disconnected as the connection state of the LSP. The time zone among the options indicates the time zone to which the policy is applied (for example, from 19:00:00 on October 1, 2020 to 20:30:00 on October 1, 2020). The pre-path generation indicates on / off information for pre-generating a path when the permitted time is reached within the time registered in the time zone.

[0078] That is, when the pre-path generation is on, it indicates that a path is being generated because the permitted time has been reached, and when the pre-path generation is off, it indicates that no path has been generated because the permitted time has not been reached. The paths p1 and p2 are the path information of the LSP, and a list of nodes (a list of IP addresses of each node) used for the relay of the LSP is registered. This path information is used, for example, for selecting candidates for a detour path when a path failure occurs.

[0079] <Execution from the occurrence of an IGMP trigger to IP multicast> Next, the operations from the occurrence of an IGMP trigger to the execution of IP multicast will be described with reference to FIGS. 11 to 13.

[0080] FIG. 11 is a diagram showing an example of an operation sequence in which an IGMP trigger occurs and IP multicast is performed. [Step S21] In the operation setting (e.g., manual setting) of the transmission device (sender) 10-2, an IP address for a UNI is registered (UNI / IPv4 network address registration). The transmission device 10-2 also receives information such as the prefix of an IPv6 address advertised by ICMPv6 (setting by receiving an RA).

[0081] [Step S22] The transmission device 10-2 generates an address information table T1 in response to the setting performed in step S21. By generating the address information table T1, the node ID (router ID-1) is associated with the subordinate UNI segment.

[0082] [Step S23] Table synchronization is performed between the transmission device 10-2 and the transmission device (receiving side) 10-1, and the information in the address information table T1 is shared between the transmission devices 10-1 and 10-2.

[0083] In this way, the addresses and device IDs of the access networks under the transmission devices 10-1 and 10-2 are shared autonomously in a synchronized manner among all the transmission devices connected to the relay network, thereby improving the efficiency of the parameter setting work. Note that the processes from step S21 to step S23 are preparation processes before executing IP multicast.

[0084] [Step S24] The user terminal 40 transmits to the transmission device 10-1 an IGMPv3 trigger (message) including the multicast group ID (G1), the multicast source ID (source ID (S1)), and the IP address (L1) of the user terminal 40. Note that in RSVP, a trigger means a message that generates / deletes an LSP.

[0085] [Step S25] When the transmission device 10-1 receives an IGMPv3 trigger (joining a group), it executes policy control Pc1 to determine whether or not to permit IP multicast as a receiving transmission device. Policy control Pc1 determines whether or not the information included in the IGMPv3 trigger matches the registration in the policy information table T3. Details of policy control Pc1 will be described later with reference to FIG. 12.

[0086] [Step S26] If the transmission device 10-1 determines in the policy control Pc1 in step S25 that IP multicast is permitted, it transmits a control signal to the transmission device 10-2. The destination of the control signal is router ID-1, and the payload of the control signal contains information {G1, S1, L1}. Note that if multiple user terminals 40 exist under the same port of the transmission device 10-1, this L1 can be the IP address of the transmission device 10-1 indicating the UNI that accommodates the user terminal 40.

[0087] [Step S27] Upon receiving the control signal, the transmission device 10-2 executes policy control Pc2 to determine whether or not to permit IP multicast as a transmitting device. If the transmission device 10-2 determines in the policy control Pc2 that IP multicast is permitted, it creates a multicast information table T2.

[0088] The multicast information table T2 includes {G1, S1, L1}, and further includes a tunnel ID for establishing an LSP, which is assigned and registered in the multicast information table T2. Details of the policy control Pc2 will be described later with reference to FIG.

[0089] [Step S28-1] The transmission node 10-2 transmits a P2MP RSVP path message (RSVP path (P2MP)) to the transmission node 10-1 to request label allocation for the path.

[0090] [Step S28-2] Upon receiving the RSVP path message, the transmission node 10-1 returns an RSVP reservation message (RSVP Resv) to the transmission node 10-2 to notify it of the label allocation.

[0091] [Step S29] A P2MP LSP is established between the transmission devices 10-1 and 10-2. As a result, the IP multicast from the transmitting / receiving station side input to the transmission device 10-2 is transmitted to the transmission device 10-1 via the generated P2MP LSP, and the IP multicast is then transmitted from the transmission device 10-1 to the user terminal 40.

[0092] If either the policy of the above-mentioned policy controls Pc1 and Pc2 is not satisfied, no path is set up in the transit network. 12 is a flow chart showing an example of the policy control operation, illustrating the operation of the policy control Pc1 of the transmission device 10-1 performed in step S25 of FIG.

[0093] [Step S25a] Upon receiving an IGMPv3 trigger, the control unit 11 in the transmission device 10-1 determines a policy based on {G1, S1, L1} contained in the IGMPv3 trigger. Specifically, the following policy decisions (1A) to (5A) are made.

[0094] (1A) The communication information {G1, S1, L1} (first communication information) having the multicast group ID (G1), source ID (S1), and IP address (L1) of the user terminal 40 included in the IGMPv3 trigger matches the communication information {G, S, L} (second communication information) registered in the policy information table T3. If the contents of the permit in the policy information table T3 are permit, and the status of the LSP for {G1, S1, L1} is not connected, the process proceeds to step S25c.

[0095] (2A) The communication information {G1, S1, L1} having the multicast group ID (G1), the source ID (S1), and the IP address (L1) of the user terminal 40 matches the communication information {G, S, L} registered in the policy information table T3. If the contents of the permit in the policy information table T3 are permit, and the status of the LSP for {G1, S1, L1} is connected, the process proceeds to step S25b.

[0096] (3A) If at least one of the communication information {G1, S1, L1} having the multicast group ID (G1), the source ID (S1), and the IP address (L1) of the user terminal 40 does not match the communication information {G, S, L} registered in the policy information table T3, processing proceeds to step S25e.

[0097] (4A) The communication information {G1, S1, L1} having the multicast group ID (G1), the source ID (S1), and the IP address (L1) of the user terminal 40 matches the communication information {G, S, L} registered in the policy information table T3. If the contents of the permit in the policy information table T3 are not permitted, the process proceeds to step S25e.

[0098] (5A) The communication information {G1, S1, L1} having the multicast group ID (G1), the source ID (S1), and the IP address (L1) of the user terminal 40 matches the communication information {G, S, L} registered in the policy information table T3. If the contents of the permit in the policy information table T3 are permit, and the status of the LSP for {G1, S1, L1} is blocked, the process proceeds to step S25e.

[0099] [Step S25b] The control unit 11 judges whether or not a threshold time (e.g., 300 seconds) has elapsed since the previous IGMPv3 trigger was received. If the threshold time has elapsed, the process proceeds to step S25c to execute a refresh. If the threshold time has not elapsed, a refresh is deemed unnecessary and the process proceeds to step S25e. In RSVP, a refresh means maintaining an already-generated LSP.

[0100] [Step S25c] The control unit 11 searches for the node ID (NNI router ID) that contains the source {G1, S1} indicated in the IGMPv3 trigger. If the search does not return a hit, the process proceeds to step S25e. If the search returns a hit, the process proceeds to step S25d.

[0101] [Step S25d] The control unit 11 performs processing for transmitting a control signal to the transmission device 10-2 having the searched node ID. The control signal includes information on the multicast group ID (G), source ID (S), and IP address (L) of the user terminal 40, which are permitted by the policy of the policy control Pc1. This L may be the IP address of the transmission device 10-1 indicating the UNI that accommodates the user terminal 40, as in step S26 of FIG. 11.

[0102] [Step S25e] The control unit 11 discards the received IGMPv3 trigger. 13 is a flow chart showing an example of the policy control operation, which illustrates the operation of the policy control Pc2 of the transmission device 10-2 performed in step S27 of FIG.

[0103] [Step S27a] Upon receiving the control signal transmitted from the transmission device 10-1, the control unit 11 in the transmission device 10-2 determines the policy based on {G1, S1} contained in the control signal.

[0104] Specifically, the following policy decisions (1B) to (5B) are made. (1B) The communication information {G1, S1} (third communication information) having the multicast group ID (G1) and the source ID (S1) matches the communication information {G, S} (fourth communication information) registered in the policy information table T3. If the contents of the permit in the policy information table T3 are permit, and the status of the LSP for {G1, S1} is not connected, the process proceeds to step S27b.

[0105] (2B) If the communication information {G1, S1} having the multicast group ID (G1) and the source ID (S1) matches the communication information {G, S} registered in the policy information table T3, and if the content of the permit in the policy information table T3 is permit, and if the status of the LSP for {G1, S1} is connected, the process proceeds to step S27e.

[0106] (3B) If at least one of the communication information {G1, S1} having the multicast group ID (G1) and the source ID (S1) does not match the communication information {G, S} registered in the policy information table T3, the process proceeds to step S27g.

[0107] (4B) If the communication information {G1, S1} having the multicast group ID (G1) and the source ID (S1) matches the communication information {G, S} registered in the policy information table T3, and if the contents of the permit in the policy information table T3 are not permitted, the process proceeds to step S27g.

[0108] (5B) If the communication information {G1, S1} having the multicast group ID (G1) and the source ID (S1) matches the communication information {G, S} registered in the policy information table T3, and if the contents of the permit in the policy information table T3 are permit, and if the status of the LSP for {G1, S1} is blocked, the process proceeds to step S27g.

[0109] [Step S27b] In order to generate a new LSP, the control unit 11 assigns a tunnel ID and an LSP ID, and updates the registration in the multicast information table T2. [Step S27c] The control unit 11 assigns a number to an S2L sub-LSP ID in addition to the tunnel ID and LSP ID, and updates the registration in the multicast information table T2.

[0110] [Step S27d] The control unit 11 starts a connection of the S2L sub-LSP. This connection process causes the RSVP path message shown in step S28-1 in Fig. 11 to be transmitted from the transmission node 10-2 to the transmission node 10-1.

[0111] [Step S27e] The control unit 11 judges whether or not an LSP for the IP address (L) has been established. If the LSP has not been established, the process proceeds to step S27b. If the LSP has been established, the process proceeds to step S27f.

[0112] [Step S27f] The control unit 11 continues to monitor the active state of the LSP (no control for generating an LSP is performed). If the control unit 11 recognizes that a control signal has not been received for a certain period of time (for example, 600 seconds), it disconnects the currently established LSP.

[0113] [Step S27g] The control unit 11 discards the received control signal (no control for generating an LSP is performed). As described above, in the transmission system 1-2, policy control is performed by both the sending and receiving transmission devices, and a path is generated in the relay network between the transmission devices when both the sending and receiving policies are satisfied. This makes it possible to suppress congestion of multicast paths that are generated in conjunction with IGMP, and also makes it possible to prevent unexpected path generation.

[0114] <Pre-pass generation> 14 is a diagram showing an example of an operation sequence of pre-path generation. It shows an operation in which an LSP is autonomously generated between transmission devices 10-1 and 10-2 when the device time (synchronization time of the device) managed within the transmission device reaches the permitted time (a time period including the synchronization time, hereinafter also referred to as the predetermined time).

[0115] [Step S31] In the operation setting of the transmission device (sender) 10-2, an IP address for a UNI is registered (UNI / IPv4 network address registration). The transmission device 10-2 also receives information such as an IPv6 address prefix advertised by ICMPv6.

[0116] [Step S32] The transmission device 10-2 generates an address information table T1 in response to the setting performed in step S31. By generating the address information table T1, the node ID (router ID-1) is associated with the subordinate UNI segment.

[0117] [Step S33] Table synchronization is performed between the transmission device 10-2 and the transmission device (receiving side) 10-1, and the information in the address information table T1 is shared between the transmission devices 10-1 and 10-2.

[0118] [Step S34-1] The transmission device 10-2 executes policy control to determine whether or not to permit IP multicast. In this policy control, a determination is made as to whether or not the contents of permit for {G1, S1} are permit.

[0119] [Step S34-2] The transmission device 10-1, as a receiving device, executes policy control to determine whether or not to permit IP multicast. In this policy control, a determination is made as to whether the contents of permit for {G1, S1, L1} are permit or not.

[0120] [Step S34-3] When the transmission device 10-2 detects that the device time has entered the time period registered in the policy information table T3 and the permitted time for pre-path generation has arrived, it generates a multicast information table T2. The multicast information table T2 contains {G1, S1, L1}, and furthermore, a tunnel ID for generating an LSP is assigned and registered in the multicast information table T2.

[0121] [Step S35-1] The transmission node 10-2 transmits a P2MP RSVP path message (RSVP path (P2MP)) to the transmission node 10-1 to request label allocation. [Step S35-2] Upon receiving the RSVP path message, the transmission node 10-1 returns an RSVP reservation message (RSVP Resv) to the transmission node 10-2 to notify it of the label allocation.

[0122] [Step S36] A P2MP LSP is established between the transmission devices 10-1 and 10-2. As a result, the IP multicast from the transmitting and receiving stations input to the transmission device 10-2 is transmitted to the transmission device 10-1 via the P2MP LSP.

[0123] [Step S37] The user terminal 40 transmits an IGMPv3 trigger including the multicast group ID (G1), the user terminal ID (source ID (S1)), and the IP address of the user terminal 40 (L1) to the transmission device 10-1.

[0124] [Step S38] The transmission device 10-1 transmits a control signal to the transmission device 10-2. The destination of the control signal is router ID-1, and the payload of the control signal contains information {G1, S1, L1}. Even if the transmission device 10-2 receives the control signal, the path has already been established, so the transmission device 10-2 does not control path generation. Alternatively, in the case of advance path generation, the transmission device 10-1 does not need to transmit the control signal at all.

[0125] [Step S39] The transmission device 10-1 transmits an IP multicast to the user terminal 40. As described above, in the transmission system 1-2, when the device time synchronized between the transmission devices 10-1 and 10-2 enters the time period registered in the policy information table T3 and reaches the preset permitted time, a path is generated autonomously in the relay network. This makes it possible to generate a path efficiently at the pre-registered time.

[0126] When the path is generated, the UNI of the user terminal 40 is in a blocked state. When the IGMP participation is accepted by the transmission device 10-1, the blocked state of the UNI is released, and the IP multicast is transparently forwarded from the transmission device 10-1 to the user terminal 40.

[0127] <Path control when a failure occurs> Fig. 15 is a diagram showing an example of the operation sequence of path control when a failure occurs. It shows an example of the operation of the fail safe function when a failure such as a bandwidth overflow caused by a path misconnection occurs. It is assumed that the failure occurs during path establishment by pre-path generation.

[0128] In addition, other fail-safe functions can be used in the event of bandwidth overflow, such as an emergency function that changes the RSVP path generation priority or MPLS priority to the highest to protect important lines, or a best-effort function that does not disconnect low-priority paths but keeps them connected and waits for the bandwidth overflow to be resolved.

[0129] [Step S41] When the transmission device 10-2 detects that the device time has reached the permitted time, it generates a multicast information table T2. The multicast information table T2 contains {G1, S1, L1}, and further, a tunnel ID for generating an LSP is assigned and registered in the multicast information table T2.

[0130] [Step S42-1] The transmission node 10-2 transmits a P2MP RSVP path message (RSVP path (P2MP)) to the transmission node 10-1 to request label allocation. [Step S42-2] Upon receiving the RSVP path message, the transmission node 10-1 returns an RSVP reservation message (RSVP Resv) to the transmission node 10-2 to notify it of the label allocation.

[0131] [Step S43-1] A P2MP LSP is established between the transmission devices 10-1 and 10-2. As a result, IP multicast data from the transmitting and receiving stations input to the transmission device 10-2 is transmitted to the transmission device 10-1 via the P2MP LSP.

[0132] [Step S43-2] Processing similar to steps S41 to S42-2 above is carried out between the transmission device 10-1a (receiving side) and the transmission device 10-2 (transmitting side), and a P2MP LSP is established between the transmission devices 10-1a and 10-2.

[0133] [Step S44] The transmission device 10-1a detects the occurrence of a fault, for example, by recognizing frequent occurrences of data loss. [Step S45] The transmission device 10-1a notifies all transmission devices (transmission devices 10-1 and 10-2) connected to the relay network of a fault message.

[0134] [Step S45a] The transmission device 10-1a checks whether or not there is information about alternative routes (information about detour routes) for paths that have been established within a certain period of time (the connection monitoring period of step S51 in FIG. 16) since the transmission device 10-1a received the fault message (step S52 in FIG. 16).

[0135] [Step S46] If the transmitting transmission device 10-2 receives a failure message within the connection monitoring time and there is no information about other routes, it changes the status in the information table T3 to "blocked" and sends an RSVP pathTear message to terminate the RSVP reservation.

[0136] [Step S47] The user terminal 40 transmits an IGMPv3 trigger (message) including the multicast group ID (G1), the user terminal ID (source ID (S1)), and the IP address of the user terminal 40 (L1) to the transmission device 10-1.

[0137] [Step S48] The transmission device 10-1 transmits a control signal to the transmission device 10-2. The destination of the control signal is router ID-1, and the payload of the control signal contains information {G1, S1, L1}.

[0138] [Step S49] Having received the control signal, the transmission device 10-2 executes policy control, invalidates (disconnects) the entry for the user terminal 40, and does not create a path.

[0139] 16 is a flowchart showing an example of the operation from receiving a fault message to cutting off or re-establishing a path. Note that the fault message is assumed to be transmitted at regular intervals (e.g., 10 seconds) from the transmission device where the fault occurred while the fault is occurring.

[0140] [Step S51] The control unit 11 in the transmission device that received the fault message determines whether or not there is a user terminal 40 currently being monitored for connection. If there is no user terminal 40 currently being monitored for connection, the process of step S51 is repeated. If there is a user terminal 40 currently being monitored for connection, the process proceeds to step S52.

[0141] [Step S52] The control unit 11 judges whether or not information on another route (information on a detour route) is registered in the policy information table T3. If it is registered, the process proceeds to step S53, and if it is not registered, the process proceeds to step S56.

[0142] [Step S53] The control unit 11 blocks the S2L sub-LSP in which the failure has occurred. [Step S54] The control unit 11 connects the LSP via a different route registered in the policy information table T3.

[0143] [Step S55] The control unit 11 monitors the connection of the newly connected LSP (extends the connection monitoring time). [Step S56] The control unit 11 blocks the S2L sub-LSP in which the failure has occurred.

[0144] [Step S57] The control unit 11 updates the status in the policy information table T3 to "disconnected." As described above, in the transmission system 1-2, when a faulty path is detected during streaming, if a detour path other than the faulty path is registered in the policy information, the faulty path is cut off and a detour path is generated in the transit network. This makes it possible to quickly recover from communication abnormalities caused by the service failure that has occurred and quickly restore communication.

[0145] As described above, according to the present invention, policy information for stream distribution by IP multicast is defined, and when an LSP generation trigger by IGMP is detected, an LSP based on the policy information is generated for the transit network.

[0146] This makes it possible to avoid bandwidth congestion and prevent erroneous connections. In addition, since the functions of the present invention can be realized by modifying the software / applications of an already-constructed system, it is not necessary to construct new facilities (such as SDN (Software Defined Network) devices), and costs can be reduced. Furthermore, when a fault occurs in a path, a new path is autonomously generated to avoid the faulty path, making it possible to quickly recover from the fault.

[0147] The above-described transmission device and transmission system of the present invention can be realized by a computer. In this case, a program is provided that describes the processing contents of the functions that the transmission device and transmission system should have. By executing the program on a computer, the above processing functions are realized on the computer.

[0148] The program describing the processing contents can be recorded on a computer-readable recording medium. Examples of computer-readable recording media include magnetic storage units, optical disks, magneto-optical recording media, and semiconductor memories. Examples of magnetic storage units include hard disk drives (HDDs), flexible disks (FDs), and magnetic tapes. Examples of optical disks include CD-ROM / RWs. Examples of magneto-optical recording media include MOs (Magneto Optical disks).

[0149] When distributing a program, for example, a portable recording medium such as a CD-ROM on which the program is recorded is sold. Also, the program can be stored in the memory of a server computer and transferred from the server computer to other computers via a network.

[0150] A computer that executes a program stores, for example, a program recorded on a portable recording medium or a program transferred from a server computer in its own storage unit. The computer then reads the program from its own storage unit and executes processing according to the program. Note that the computer can also read the program directly from a portable recording medium and execute processing according to the program.

[0151] The computer can also execute processing according to the programs it receives each time the programs are transferred from a server computer connected via a network. At least a part of the above processing functions can also be realized by electronic circuits such as DSPs, ASICs, and PLDs.

[0152] Although the embodiments have been described above, the configurations of the parts shown in the embodiments can be replaced with other configurations having similar functions. Any other components or steps may be added. Furthermore, any two or more configurations (features) of the above-described embodiments may be combined. [Explanation of symbols]

[0153] 1-1 Transmission system 1, 2 Transmission equipment 1a, 2a control section 1b, 2b storage section ad1, ad2 address information p0 path PC Policy Information N1 Transit network

Claims

1. A transmission device for performing stream distribution, a storage unit that stores address information for communicating with an opposing device via a relay network and policy information in which a communication policy is set when the stream distribution is performed in the relay network; a control unit that holds the address information together with the opposing device, and generates the path to the relay network based on the address information and the policy information when a generation trigger for generating a path for performing the communication is detected; The policy information is Identification information of the transmission device; Identification information of a multicast group connected to an access network under the transmission device and for which the stream distribution is performed; Identification information of a terminal connected to the access network and performing the stream distribution; Permission information indicating whether or not generation of the path is permitted; and status information indicating a connection state of the path. Transmission equipment.

2. the address information includes identification information of the transmission device and an address of the access network under the transmission device; the control unit transmits the address information of the transmission device to the opposite device connected to the relay network, receives the address information transmitted from the opposite device, and shares the address information between the transmission device and the opposite device.

2. The transmission device according to claim 1.

3. when the control unit detects the generation trigger including first communication information having identification information of the multicast group, identification information of the transmission device, and identification information of the terminal, If the first communication information matches all of second communication information having the identification information of the multicast group set in the policy information, the identification information of the transmission device, and the identification information of the terminal, and if the permission information indicates permission and the status information indicates not connected, the transmission device that received the generation trigger transmits a control signal to the opposing device indicating that the communication policy is satisfied.

2. The transmission device according to claim 1.

4. when the control unit detects the generation trigger including first communication information having identification information of the multicast group, identification information of the transmission device, and identification information of the terminal, if the first communication information matches second communication information having identification information of the multicast group, identification information of the transmission device, and identification information of the terminal, which are set in the policy information, and if the permission information indicates permission and the status information indicates connected, determine whether or not a predetermined time has elapsed since the previous reception of the generation trigger, and if the predetermined time has elapsed, transmit a control signal indicating that a communication policy is satisfied on the side of the transmission device that received the generation trigger, and if the predetermined time has not elapsed, discard the generation trigger.

2. The transmission device according to claim 1.

5. when the control unit detects the generation trigger including first communication information having identification information of the multicast group, identification information of the transmission device, and identification information of the terminal, discarding the generation trigger when the first communication information does not match all of second communication information having the identification information of the multicast group set in the policy information, the identification information of the transmission device, and the identification information of the terminal; 2. The transmission device according to claim 1.

6. when the control unit detects the generation trigger including first communication information having identification information of the multicast group, identification information of the transmission device, and identification information of the terminal, discarding the generation trigger when the first communication information matches second communication information having the identification information of the multicast group, the identification information of the transmission device, and the identification information of the terminal set in the policy information, and the permission information indicates non-permission; 2. The transmission device according to claim 1.

7. when the control unit detects the generation trigger including first communication information having identification information of the multicast group, identification information of the transmission device, and identification information of the terminal, discarding the generation trigger when the first communication information matches second communication information having the identification information of the multicast group set in the policy information, the identification information of the transmission device, and the identification information of the terminal, and when the permission information indicates permission and the status information indicates that the path is being blocked; 2. The transmission device according to claim 1.

8. when the control unit receives the control signal including third communication information having identification information of the multicast group and identification information of the transmission device, generating the path when the third communication information is identical to the fourth communication information having the identification information of the multicast group and the identification information of the transmission device set in the policy information, the permission information indicates permission, and the status information indicates no connection; 4. The transmission device according to claim 3.

9. when the control unit receives the control signal including third communication information having identification information of the multicast group and identification information of the transmission device, if the third communication information is identical to the fourth communication information having the identification information of the multicast group and the identification information of the transmission device set in the policy information, and the permission information indicates permission, and the status information indicates connected, determine whether or not the path to the terminal has been generated, and if the path to the terminal has not been generated, generate the path, and if the path to the terminal has been generated, perform activity monitoring of the path.

4. The transmission device according to claim 3.

10. when the control unit receives the control signal including third communication information having identification information of the multicast group and identification information of the transmission device, discarding the control signal when the third communication information does not entirely match the identification information of the multicast group set in the policy information and the fourth communication information having the identification information of the transmission device; 4. The transmission device according to claim 3.

11. when the control unit receives the control signal including third communication information having identification information of the multicast group and identification information of the transmission device, discarding the control signal when the third communication information is identical to the identification information of the multicast group set in the policy information and the fourth communication information having the identification information of the transmission device, and when the permission information indicates non-permission.

4. The transmission device according to claim 3.

12. when the control unit receives the control signal including third communication information having identification information of the multicast group and identification information of the transmission device, discarding the control signal when the third communication information is identical to the identification information of the multicast group set in the policy information and the fourth communication information having the identification information of the transmission device, the permission information indicates permission, and the status information indicates not being relayed.

4. The transmission device according to claim 3.

13. the control unit generates the path in advance in the relay network before detecting the generation trigger when a device time indicating a time to be synchronized with the opposite device reaches a predetermined time.

2. The transmission device according to claim 1.

14. the policy information includes route information of the path generated in the relay network, and when the control unit detects the path in which a failure has occurred during the stream distribution, if the route information includes information of a detour path other than the path in which the failure has occurred, the control unit blocks the path in which the failure has occurred and generates the detour path in the relay network.

2. The transmission device according to claim 1.

15. a first transmission device including: a first storage unit that stores address information for communicating with a second transmission device via a relay network and first policy information in which a communication policy for performing stream distribution in the relay network is set; and a first control unit that holds the address information together with the second transmission device and generates a path for the relay network based on the address information and the first policy information when a generation trigger for generating a path for the communication is detected; the second transmission device includes a second storage unit that stores the address information and second policy information in which a communication policy is set when the stream distribution is performed in the relay network, and a second control unit that holds the address information together with the first transmission device and generates the path to the relay network based on the address information and the second policy information; The first policy information is Identification information of the first transmission device; Identification information of a multicast group connected to a first access network under the first transmission device and for which the stream distribution is performed; and Identification information of a terminal connected to the first access network and through which the stream distribution is performed; and Permission information indicating whether or not generation of the path is permitted; status information indicating a connection state of the path; The second policy information is Identification information of the second transmission device; and Identification information of a multicast group connected to a second access network under the second transmission device and for which the stream distribution is performed; and Identification information of a terminal connected to the second access network and through which the stream distribution is performed; and Permission information indicating whether or not generation of the path is permitted; and status information indicating a connection state of the path. Transmission system.

16. The transmission device storing address information for communicating with an opposing device via a relay network and policy information in which a communication policy for performing stream distribution in the relay network is set in a storage unit; Holding the address information together with the opposing device; when detecting a generation trigger for generating a path for performing the communication, generating the path for the transit network based on the address information and the policy information; The policy information is Identification information of the transmission device; Identification information of a multicast group connected to an access network under the transmission device and for which the stream distribution is performed; Identification information of a terminal connected to the access network and performing the stream distribution; Permission information indicating whether or not generation of the path is permitted; and status information indicating a connection state of the path. Transmission method.

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