JP2015109532A - Communication system and communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for effective use of a band in multicast communication.SOLUTION: Only a multicast transmission node holds a management table that holds topology information on nodes constituting a ring network, and information on which node a client requesting reception of a multicast packet belongs to. When the multicast transmission node transmits a multicast packet, if it detects presence of a node which it wants the multicast to reach on a network, the number of hops is calculated from a transmission source node to that node from the value of a TTL, and is given as a TTL of the multicast packet. The multicast packet reaches the node which the packet is desired to reach and after that the packet is discarded by the TTL value; whereby, a network band of a node beyond that node becomes vacant, and in the ring network, effective use of a network band can be achieved.

Description

  The present invention relates to a communication system and a communication apparatus.

  In multicast communication, in general, a multicast packet is transmitted from a server that provides a multicast service to a client that requests the service, so that the multicast packet is transmitted from the transmission source node to all nodes belonging to the network. Will be. In this case, since multicast packets are also transmitted to nodes that do not need to be provided with services, the effective bandwidth of the network is compressed and cannot be used effectively. When there are a plurality of services, the effective bandwidth of the network is further compressed.

  In this regard, International Publication WO 2004/064335 (Patent Document 1) states that “in a ring network, a transmission host and a reception node that communicate by multicast share entry information indicating a node related to multicast communication. The transmitting node and the receiving node broadcast the entry information on the ring network and share topology information related to the positional relationship on the ring network between the nodes. Referring to the entry information and the topology information, the transmission direction of the information to be transmitted by multicast is determined, the information is multicast transmitted in the transmission direction, and the receiving node receives the information in the transmission direction. Discard the information when there is no receiving node It has been described (see Abstract). In other words, in Patent Document 1, all nodes belonging to a ring network hold a management table containing all information in the network, and each management node has a management table so that individual nodes can communicate with each other. Thus, it is possible to effectively use the bandwidth in the multicast communication in the ring network (see “Disclosure of the Invention” in Patent Document 1).

WO2004 / 064335

  In Patent Document 1, since each node needs to have a management table for each multicast service, the number of multicast services is proportional to the number of entries in the management table. If there are many multicast services, the management table area will increase, and it will be necessary to update the management table on all nodes. This will increase the processing load on all nodes and increase the processing load on the entire network. Is expected.

  Therefore, in the technique of Patent Document 1, in the multicast communication in the network that provides the multicast service, the processing load at the node and the processing of the entire network are performed while effectively using the effective bandwidth without reducing the effective bandwidth of the network. The load could not be reduced.

  The present invention has been made in view of such problems of the conventional technology. That is, an object of the present invention is to provide a processing load at a node and a processing load of the entire network while effectively utilizing the effective bandwidth without reducing the effective bandwidth of the network in multicast communication in a network that provides a multicast service. Is to reduce

  In order to solve the above-described problem, in the communication system that transmits and receives a packet between a plurality of communication devices, the communication device identifies a first transmission unit that transmits the packet and a service distributed by the multicast packet. A first storage unit that stores an identifier to be associated with a first lifetime that decreases every time a packet is transferred by another communication device, and a first control unit that controls each unit The other communication device includes a second transmission unit that transmits the packet, a second storage unit that stores the first lifetime, and a second control unit that controls each unit, The control unit causes the first transmission unit to transmit a control multicast packet used for control with another communication device to which the first lifetime is stored, which is stored in the first storage unit. Control multicast packets for control The first transmission unit transmits a control packet used for control with the communication device to which the first lifetime is stored, stored in the second storage unit, to the second transmission unit. When the first packet is received, the first lifetime is read from the received control packet, and the first lifetime is stored in the first storage unit based on the read first lifetime and the first lifetime stored in the first storage unit. Is calculated as the second lifetime in which the value decreases every time a multicast packet for delivering a service is transferred by another communication device. There is provided a communication system characterized in that a multicast packet for distributing a service assigned with a second lifetime is transmitted from a first transmission unit in association with an identifier and stored in a first storage unit.

  ADVANTAGE OF THE INVENTION According to this invention, a transmission source node can transmit a multicast packet with respect to a desired transmission range with respect to one multicast service. Therefore, in multicast communication in a network that provides a multicast service, the effective bandwidth is effectively used without reducing the effective bandwidth of the network, and the processing load of the node is reduced while reducing the processing load of the entire network. Can do.

It is an example of a block diagram of a ring type MPLS network. It is an example of the figure of a MPLS packet header format. It is an example of the block block diagram of a transmission node. It is an example of the block block diagram of a receiving node. It is an example of the block block diagram of a transmission / reception node. It is an example of the sequence diagram in service delivery. It is an example of the operation | movement flowchart figure of the transmission node which received the packet. It is an example of the operation | movement flowchart figure of the receiving node in service delivery. It is a structural example of the management table which a transmission node has. It is an example of a service transmission range diagram when there are a plurality of services. It is a structural example of the management table which each transmission node has when there are a plurality of services.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  An example of the concept of a network in this embodiment is shown in FIG. In the present embodiment, a ring type MPLS (Multi Protocol Label Switching) network will be described as an example of the network. It should be noted that the present invention can also be applied to a network that provides a multicast service other than a ring network.

  MPLS refers to, for example, an IP (Internet Protocol) layer transfer process for each packet by assigning a fixed-length label to a packet flow identified based on layer 3 transfer information and transferring the packet based on the label. This is a technology that omits.

  The ring-type MPLS network includes nodes 101 and 102 (nodes 102 and 102-1 to 102-3), which are communication apparatuses that transmit and receive packets, a service distribution server 111, and a client 112. The node 101 includes a CPU (Central Processing Unit), an FPGA (Field-Programmable Gate Array), a memory, and various optical modules. Although details will be described later, the CPU includes a transmission control unit, the FPGA includes an EoMPLS (Ethernet (registered trademark), the same applies hereinafter) over MPLS conversion unit, a TTL determination unit, a service determination unit, a memory includes a transmission storage unit, and the like. Is stored and works. Similarly, the node 102 also stores and operates a reception control unit in the CPU, an EoMPLS conversion unit or TTL determination unit, a packet determination unit, a multicast unit, and a memory in the FPGA.

  Here, the clockwise direction (clockwise direction) in the ring-type MPLS network is 0 system, and the counterclockwise direction (counterclockwise direction) is 1 system. Each node transmits / receives an MPLS packet to which an MPLS header is added to / from another node. The basic concept of the present embodiment will be described. A service name 901 of a multicast service, a transmission TTL (Time To Live) value 902 that is a multicast service distribution range, and an initial TTL value 903 are transmitted to a node 101 (hereinafter referred to as “transmission node 101”) to which the service distribution server 111 is connected. Management table 900 (FIG. 9).

  Here, the service name is an arbitrary identifier for identifying each service. In this embodiment, as a multicast service, a content distribution service such as a video image or an information distribution service that distributes various types of information is assumed. However, the present invention is not limited to these.

  The TTL value is a value that represents the valid period or lifetime of the packet, and is represented by an integer value up to “255”. This is a survival value whose value decreases by 1 every time the node 101 or 102 is routed once, that is, every time a packet is relayed or transferred by the node 101 or 102. A packet whose TTL value is 0 is discarded at the node 101 or 102. Thus, the TTL value is a value serving as a reference for transfer. The TTL value may be the Hop Limit value of Ipv6.

  The multicast service distribution range means a transmission range of multicast packets used for multicast service distribution. The transmission TTL value 902 is a TTL value for transmission when a multicast packet is transmitted. The initial TTL value 903 is a TTL value at the time of transmitting a query packet (hereinafter referred to as “packet (query)”) that is a packet for notifying the start of the service. Although details will be described later, the same value as the initial TTL value 903 is stored in the node 102 as a TTL value predetermined in the system, and a packet that responds to the transmitting node 101 that the node 102 receives the service Is used as a TTL value when transmitting a participation notification packet (packet (report)).

  As a method of controlling the transmission range of the multicast packet, a method of controlling the TTL value at the time of multicast service distribution is used. In this embodiment, the TTL value is used as a method for controlling the transmission range of the multicast packet.

  Here, an example of the MPLS packet header format will be described with reference to FIG. A label 201 is a 20-bit integer and is an identifier that is given between 0 and 1048575 and determines a transfer destination. The label 201 can distinguish packet types such as a multicast packet, a unit cast packet, a packet (query), and a packet (report). A TC (Traffic Class) 202 is a field for determining a traffic class. S is a stack bit, and is a field indicating the last label when two or more MPLS labels 201 are placed in one MPLS packet.

  The TTL 204 is a value representing the valid period of the packet, and is represented by an integer value up to “255” as described above. The value is decreased by 1 each time the node 101 or 102 is passed through. A packet whose TTL value is “0” is discarded at the node 101 or 102. This function prevents an infinite loop of packets due to path setting errors or physical connection errors. When each node 101 or 102 assigns a TTL value to a packet, it is assigned to the TTL 204 of the MPLS header.

  The outline of the operation between the nodes will be described. The service distribution server 111 transmits a packet (query) notifying the start of the service at the time of service distribution to each client 112 via the transmission node 101 in the 0-system direction. The service name is stored in the service name 901 of the management table 900 (FIG. 9) of the transmission node 101. This packet (query) is a multicast packet for control that inquires whether or not to receive a multicast service, that is, whether or not to join a group that distributes multicast packets. At this time, the TTL value stored in the initial TTL value 903 of the management table 900 is assigned to the packet (query). The TTL value stored in the initial TTL value 903 is a TTL value predetermined by the system. In this embodiment, “255” is set as the TTL value predetermined in this system. The initial TTL value 903 can be set as appropriate depending on the network configuration.

  When each client 112 that wishes to receive a service receives a packet (query), a packet called a report, which is a participation notification packet, is sent to each service delivery server 111 via each node 102 (hereinafter referred to as “receiving node 102”). To transmit in the 1 system direction. This packet (report) is a control packet for notifying that a service is received and a multicast packet is distributed. At this time, the TTL value assigned to the packet (report) transmitted to the service distribution server 111 is “255”, which is a TTL value predetermined in the system, similar to the initial TTL value 903 assigned to the packet (query). It is.

  The transmission node 101 receives a packet (report) from the 1-system direction, and reads the TTL value included in the packet, thereby subtracting the read TTL value from the initial TTL value 903 “255” at the time of transmission. The report) calculates the number of hops, which is the number of relayed and transferred by each receiving node 102 and the number of nodes that have passed. That is, “initial TTL value−read TTL value = number of nodes passed (number of hops)”, and the amount of decrease in the TTL value is calculated as the number of nodes (number of hops) that the packet (report) has passed. Is possible. A TTL value obtained by adding “1” to the calculated number of hops is recorded as a transmission TTL value 902 in the management table 900, and the recorded transmission TTL value 902 is used as a TTL value at the time of service distribution. “1” is added to the calculated number of hops because the TTL value of the packet transmitted from the transmitting node 101 to the most adjacent receiving node 102, that is, the receiving node 102 having the hop number “0” is at least “ This is because it needs to be “1”. The above-described method for calculating the number of nodes (hops) and the TTL value at the time of service distribution is an example, and the number of nodes (number of hops) can be calculated, and the TTL value at the time of service distribution can be transmitted to the nearest node Any calculation method that can calculate a value may be used.

  When the transmission node 101 assigns the recorded transmission TTL value 902 as a TTL value at the time of service distribution to the multicast packet that provides the service, it can be distributed to the receiving node 102 that wants to receive the service, and the TTL value is “0” after that. Therefore, the multicast packet is discarded, that is, it does not occupy the band ahead.

  In the present embodiment, the operation and function of each node will be described with an example in which the transmission node 101 transmits a packet (query) in the 0-system direction and receives a packet (report) from the 1-system direction. It is also possible to transmit a packet (query) in the 1-system direction and receive a packet (report) from the 0-system direction. In this case, although not described in the present embodiment, each node is provided with a functional unit necessary to realize this.

  Examples of the internal block configuration of the node are shown in FIGS. In addition, the same code | symbol is attached | subjected to the function part which carries out the same operation | movement by FIG.3 and FIG.4, and it demonstrates in FIG.

  FIG. 3 is an example of an internal block configuration diagram of the transmission node 101 to which the service distribution server 111 is connected. The transmission node 101 includes a packet receiving unit 301 that receives a packet from the clockwise direction (system 0) in the ring MPLS network, a packet transmission unit 302 that transmits a packet to the system 0, and a counterclockwise direction (system 1). A packet receiving unit 303 for receiving a packet of the packet, a packet transmitting unit 304 for transmitting a packet to the first system, a TTL value is detected from the received packet, and it is determined whether it is discarded or transferred. The TTL determination unit 306 that transmits the reduced packet and the Ethernet packet received from the service distribution server 111 adds an MPLS header to convert the packet into an MPLS packet, and deletes the MPLS header from the MPLS packet that is transmitted to the service distribution server 111. EoMPLS conversion unit 305 for converting to And determining the service determination unit 307 whether the service or not to provide the over-de, a transmission control unit 308 that controls the entire apparatus, and a transmission storage unit 309 for storing management table 900.

  In this embodiment, the layer 2 packet is referred to as an “Ethernet packet” as a specific example, but the present invention is not limited to this.

  The transmission control unit 308 also operates as a TTL calculation unit 310 that rewrites the management table 900 by calculating the distance (number of hops) from the reception node 102 that transmitted the packet (report) based on the TTL value of the received packet (report). . Further, the EoMPLS conversion unit 305 is controlled to give an instruction to give the TTL value stored in the initial TTL value 903 of the management table 900 stored in the transmission storage unit 309 to the MPLS packet (query). Also, control is performed to record the entry of the multicast service group in the management table 900.

  FIG. 4 is an example of an internal block configuration diagram of the receiving node 102 to which the client 112 is connected. The receiving node 102 determines whether or not the packet received from the 0-system receiving unit 301 is a multicast packet, a multicast determination unit 312 that processes the multicast packet, and an MPLS that is transmitted to the client 112 that receives the service. An EoMPLS conversion unit 305 that converts packets into Ethernet packets and converts Ethernet packets received from the client 112 into MPLS packets, a reception control unit 313 that controls the entire apparatus, and a reception memory that stores a TTL value predetermined by the system Part 314.

Example 1
With regard to service distribution, detailed operations when a service start notification (query), a service reception response (report), and a service stop notification (report) are transmitted will be described.

  FIG. 6 shows a series of operation sequences between the transmission node 101 and the reception node 102 for service distribution. The internal operation of the transmission node 101 is shown in FIG. 7, and the internal operation of the reception node 102 is shown in FIG.

  FIG. 6 is an example of an operation sequence diagram of service distribution. Each receiving node 102 shows a receiving node 102-1 and a receiving node 102-2 as a part thereof.

  First, regarding the operation at the time of starting the service, an example will be described in which only the receiving node 102-1 of each receiving node 102 starts receiving the service. At the start of the service, the transmitting node 101 performs an operation of distributing the service by transmitting a packet (query) to each receiving node 102.

  When receiving the packet (query) for notifying the start of the multicast service from the service distribution server 111, the transmission node 101 to which the service distribution server 111 is connected gives the TTL value “255” stored in the initial TTL value 903. Transmission is performed in the 0-system direction to each receiving node 102 in the ring-type MPLS network (S001). At this time, the transmission node 101 records an entry of the multicast service group (service name) in the management table 900. The transmission TTL value 902 of the management table 900 has an initial setting value “0”.

  The receiving node 102-1 that has received the packet (query) copies the packet (query), rewrites the TTL value of one packet (query) from “254” to “253”, and then receives the next receiving node 102- 2 and transmits one packet (query) to the clients 112-2 to 112-4. Receiving node 102-1 where clients 112-2 to 112-4 receive the multicast service transmits a packet (report) with a TTL value “255” predetermined by the system in the 1-system direction to service distribution server 111. (S002).

  The receiving node 102-2 that has received the packet (query) transfers the packet (query) to the next receiving node 102-3 and transmits it to the client 112-5 in the same manner as the receiving node 102-1, but the client 112- Since 5 does not receive the multicast service, the packet (report) is not transmitted.

  The transmission node 101 that has received the packet (report) from the reception node 102-1 sets the number of nodes (hops) that have passed using the TTL value “254” included in the received packet (report) to “255−254 = 1”. The transmission TTL value 902 “0” is calculated, and “1” is added to the calculated node number (hop count) “1” to rewrite the value “2”, and the transmission TTL value 902 “2” is given. A multicast packet that provides a service is transmitted in the 0-system direction, and distribution of the service is started (S003). That is, the number of hops is calculated as “1” from “255−254 = 1”, and “1” is added to this value, so that the transmission TTL value 902 is rewritten from “0” to “2”.

  The TTL value “2” assigned to the multicast packet that provides the service is decremented by 1 from the TTL value “2” to “1” at the receiving node 102, and the receiving node 102-1 has the TTL value “1”. A packet arrives. Therefore, the receiving node 102-1 can receive the multicast packet that provides the service, and the clients 112-2 to 112-4 connected to the receiving node 102-1 can receive the service. On the other hand, the receiving node 102-1 subtracts 1 from the TTL value “1” assigned to the multicast packet providing the service, and discards the packet because the TTL value becomes “0”.

  As a result, the multicast packet providing the service is not transferred to the receiving node 102-2 that does not receive the service.

  Next, regarding the operation in which each receiving node 102 not subscribed to the service subscribes to the service, only the receiving node 102-1 has subscribed to the service among the receiving nodes 102, and the receiving node 102-2 has the service. An example of starting the reception of will be described.

  When the receiving node 102-2 not subscribed to the service receives a request for receiving the service from the client 112-5 without being triggered by a packet (query) that is a service start notification, the receiving node 102-2 is sent to the group that distributes the multicast packet. A TTL value “255” determined in advance by the system is assigned to a packet (report) of a service reception response, which is a packet notifying participation, and transmitted to the transmission node 101 itself (S004).

  The transmitting node 101 that has received the packet (report) from the receiving node 102-2 transferred by the receiving node 102-1 has passed through the TTL value “253” included in the received packet (report). (The number of hops) is calculated from “255−253 = 2”. Since the value “3” calculated by adding “1” to the calculated value “2” is larger than the transmission TTL value 902 that is “2”, the transmission TTL value 902 “2” is calculated to the calculated value “3”. A multicast packet that provides a service to which rewriting and transmission TTL value 902 “3” is assigned is transmitted in the 0-system direction, and distribution of the service to the receiving node 102-1 and the receiving node 102-2 is started (S005).

  The receiving node 102-1 that has already received the service decrements the TTL value “2” included in the multicast packet that provides the service by 1 and forwards it to the next receiving node 102-2. The client 112-5 connected to the receiving node 102-2 can receive the service.

  Next, regarding each receiving node 102 subscribing to the service who wants to stop the service and leaves the service, among the receiving nodes 102, the receiving node 102-1 and the receiving node 102-2 receive the service. An example in which the receiving node 102-2 leaves the service will be described.

  When the receiving node 102-2 that has subscribed to the service receives a request for stopping the reception of the service from the client 112-5, the stop notification of the service, which is a packet for notifying that the multicast packet is to be separated from the group. TTL value “255” determined in advance by the system is assigned to the packet (report) and transmitted to the transmission node 101 itself (S006).

  The service stop notification packet (report) and the service reception response packet (report) are distinguished by the transmitting node 101 because the MPLS labels included in the packets are different.

  The transmitting node 101 that has received the packet (report) from the receiving node 102-2 transferred by the receiving node 102-1 has passed through the TTL value “253” included in the received packet (report). (The number of hops) is calculated from “255−253 = 2”. The value “3” calculated by adding “1” to the calculated value “2” is the same as the transmission TTL value 902 that is “3”, so that a packet (query) notifying the start of the service is transmitted again. The update processing of the transmission TTL value 902 is started (S007).

  The reception node 102-1 that has received the packet (query) transfers the packet (query) to the next reception node 102-2 and transmits it to the clients 112-2 to 112-4 in the same manner as when the service is started. The receiving node 102-1 on which the clients 112-2 to 112-4 continue to receive the multicast service receives a packet (report) of the service reception response to which the TTL value “255” predetermined by the system is given to the service distribution server 111. Transmit (S008).

  The receiving node 102-2 that has received the packet (query) transfers the packet (query) to the next receiving node 102-3 and transmits it to the client 112-5 in the same manner as the receiving node 102-1, but the client 112- No. 5 wants to stop the service and does not receive the multicast service, and therefore does not transmit a service reception response packet (report). When the receiving node 102-2 receives a notification that the client 112-5 wants to stop the service and stores the notification in the receiving storage unit 314, the receiving node 102-2 receives the packet ( It is not necessary to determine whether or not to participate in the service with respect to (query), and to transmit the packet (query) to the client 112-5.

  The transmission node 101 that has received the service reception response packet (report) from the reception node 102-1 uses the TTL value “254” included in the received packet (report), and the number of nodes (hop count) “1” passed. The transmission TTL value 902 is updated by updating the transmission TTL value 902 by rewriting the value “2” calculated by adding “1” to the calculated value “1”. The multicast packet providing the service is transmitted, and distribution of the service to the receiving node 102-1 is started (S009).

  As a result, the multicast packet is transferred to the receiving node 102-1 that wants to continue receiving the service, but the multicast packet is not transferred to the receiving node 102-2 that wants to stop the service.

  The operation of the transmission node 101 when transmitting a packet (query) that is a service start notification will be described.

  When receiving the Ethernet packet (query) for notifying the start of the multicast service from the service distribution server 111, the EoMPLS conversion unit 305 of the transmission node 101 to which the service distribution server 111 is connected converts it to an MPLS packet (query). At this time, the EoMPLS conversion unit 305 acquires the service name of the multicast service included in the packet (query), notifies the transmission control unit 308, and assigns the acquired service name to the label 201 of the MPLS header. The transmission control unit 308 records the notified service name in the service name 901 of the management table 900 stored in the transmission storage unit 309 to create a multicast service group entry. This entry includes an initial set value “0” of the transmission TTL value 902 and an initial TTL value 903 “255”. Further, the transmission TTL value 902 is updated as will be described later.

  The transmission control unit 308 outputs to the EoMPLS conversion unit 305 an instruction to attach the TTL value “255” stored in the initial TTL value 903 to the MPLS packet (query). In response to the instruction from the transmission control unit 308, the EoMPLS conversion unit 305 adds the specified TTL value “255” to the TTL 204 of the MPLS header of the MPLS packet (query), and transmits it to the 0-system packet transmission unit 302. The 0-system packet transmission unit 302 transmits the MPLS packet (query) with the TTL value “255” to the ring-type MPLS network.

  When the transmission node 101 provides a plurality of multicast services, an entry in the management table 900 is created for each service name.

  FIG. 7 is an example of an operation flowchart of the transmission node 101 that has received a packet.

  When the MPLS packet is received by the 1-system packet receiving unit 303 (S100), it is transferred to the service determining unit 307. The service determination unit 307 determines whether the transferred packet is a packet (report) or a normal packet (S101). If the packet is a normal packet (N in S101), the service determination unit 307 transfers the packet to the 1-system packet transmission unit 304. (S103) In the case of a packet (report) (Y in S101), it is a packet (report) having a service name that matches the service name 901 of the management table 900, that is, whether or not the service is provided by the own node. If the service is not a service provided by the own node (N in S102), the packet is transferred to the 1-system packet transmitter 304 (S103), and the service is provided by the own node. (Y in S102) indicates that the service stop notification of leaving from the group that distributes the multicast packet is stopped. Whether a packet (reports) determines an MPLS label (S104), if not a packet service stop notification (report) (S104: N), the transfer to the transmission control unit 308 (S105). That is, if the packet is a service reception response packet (report) that is a response to receive a service, the packet is transferred to the transmission control unit 308 (S105).

  The transmission control unit 308 operates as the TTL calculation unit 310, reads the TTL value of the received packet (report), and is calculated from “initial TTL value−read TTL value = number of nodes passed (hop count)” The TTL value calculated by adding “1” to is compared with the setting value of the transmission TTL value 902 of the management table 900 associated with the service name included in the packet (report) (S106), and the transmission TTL of the management table 900 is compared. When the value is smaller than the setting value of the value 902 (N in S106), the process ends. When the value is larger than the setting value of the transmission TTL value 902 (Y in S106), the setting value of the transmission TTL value 902 is rewritten to the calculated TTL value. The transmission TTL value 902 is updated (S107).

The transmission control unit 308 issues an instruction to the EoMPLS conversion unit 305 to give the TTL value stored in the transmission TTL value 902 of the management table 900 to the multicast packet transmitted by the server 111 that provides the service. In response to an instruction from the transmission control unit 308, the EoMPLS conversion unit 305 adds a MPLS header including a TTL value to a multicast packet that provides a service, converts the packet, and transmits the packet to the 0-system packet transmission unit 302. The 0-system packet transmission unit 302 transmits the multicast packet to which the TTL value is added to the ring type MPLS network (S108).
Therefore, the transmission node 101 receives the packet (report) of the service reception response from each reception node 102, and the setting value of the transmission TTL value 902 in the management table 900 is obtained by the process of calculating the TTL value. It is a value calculated from the packet (report) received from the receiving node 102 having the largest number.

  If the packet is a service stop notification packet (report) (Y in S104), the packet is transferred to the transmission control unit 308 (S109).

  The transmission control unit 308 operates as the TTL calculation unit 310 to read the TTL value of the received service stop notification (report), and calculates from “initial TTL value−read TTL value = number of passed nodes (hops)”. The TTL value calculated by adding “1” to the calculated value is compared with the set value of the transmission TTL value 902 of the management table 900 (S110), and when it is not the same as the set value of the transmission TTL value 902 (N of S110) When the transmission TTL value 902 is the same as the set value of the transmission TTL value 902 (Y in S110), the transmission TTL value 902 is updated. That is, when the calculated TTL value and the set value of the transmission TTL value 902 are the same, a service stop notification packet (report) is received from the farthest receiving node 102 among the receiving nodes 102 receiving the service. It is determined that the transmission has been received, and the transmission TTL value 902 is updated.

  The transmission control unit 308 sets the current transmission TTL value 902 setting value, which is a setting value of the TTL value that can be distributed to the farthest receiving node 102 that has transmitted the service stop notification packet (report), as an MPLS packet (query). Is given to the EoMPLS conversion unit 305 (S111). In response to the instruction from the transmission control unit 308, the EoMPLS conversion unit 305 assigns the set value of the transmission TTL value 902 to the packet (query) and transmits the packet to the 0-system packet transmission unit 302 (S112). The 0-system packet transmission unit 302 transmits the MPLS packet (query) to which the setting value of the transmission TTL value 902 is added to the ring-type MPLS network (S113). After transmitting the packet (query), the transmission control unit 308 initializes the transmission TTL value 902 and records the initial value “0” (S114).

  In S111, the transmission control unit 308 may issue an instruction to add an initial transmission TTL value 903 “255” to the MPLS packet (query) to the EoMPLS conversion unit 305. In this case, the transmission TTL value 902 may be initialized before or after the transmission of the MPLS packet (query) to which the initial transmission TTL value 903 “255” is added.

  When the system 1 packet receiving unit 303 receives the MPLS packet (S100), it is an MPLS packet (report) (Y in S101), a service provided by the own node (Y in S102), and a service reception response In the case of a packet (report) (N in S104), the TTL calculation unit 310 reads the TTL value of the received packet (report) and reads “initial TTL value−read TTL value = number of nodes passed (hop count). The TTL value calculated by adding “1” to the value calculated from “” is compared with the set value of the transmission TTL value 902 in the management table 900 (S106). Since the transmission TTL value 902 is initialized to “0” in S114, the calculated TTL value is larger than the initial value “0” that is the setting value of the transmission TTL value 902 in the management table 900 (Y in S106). The transmission TTL value 902 is updated by rewriting the set value of the transmission TTL value 902 with the calculated TTL value (S107).

  The transmission control unit 308 sets the TTL value stored in the transmission TTL value 902 of the management table 900 in the TTL value 204 in the MPLS header 200 and instructs the EoMPLS conversion unit 305 to give it to a multicast packet that provides a service. In response to the instruction from the transmission control unit 308, the EoMPLS conversion unit 305 adds an MPLS header in which the TTL value stored in the transmission TTL value 902 is set to the multicast packet that provides the service, and the 0-system packet transmission unit The 0-system packet transmission unit 302 transmits the multicast packet with the TTL value to the ring-type MPLS network (S108).

  Accordingly, the transmission node 101 initializes the set value of the transmission TTL value 902 upon reception of a service stop notification packet (report) from each reception node 102, and again receives a service reception response packet ( In the process of calculating the TTL value, the setting value of the transmission TTL value 902 is obtained from the receiving node 102 having the largest number of nodes (hops) that have passed among the receiving nodes 102 that want to receive the service. The value calculated from the received packet (report), that is, the number of nodes (hop count) up to the latest farthest receiving node 102 having the client 112 desiring to receive the service is rewritten and updated. .

  In S104, it is possible to determine whether or not the packet is a service reception response packet (report) based on the MPLS label. In this case, if the packet is a service reception response packet (report), the process proceeds to S105. If the packet is not a service reception response packet (report), the process proceeds to S109.

  FIG. 8 is an example of an operation flowchart of the receiving node 102 that has received a packet.

  The receiving node 102 to which the client 112 is connected receives the MPLS packet (query) by the 0-system packet receiving unit 301 (S200), and is transferred to the packet determining unit 311. The packet determination unit 311 determines whether the transferred packet is a multicast packet (S201). If the packet is a multicast packet (Y in S201), the packet determination unit 311 transfers the packet to the multicast unit 312 (S202). The multicast unit 312 copies the packet (query), delivers one to the client 112 via the EoMPLS conversion unit 305, and transfers the other to the TTL determination unit 306 (S203). The TTL determination unit 306 determines the TTL value of the received packet (query) (S206). If the TTL value is not “1” (N in S206), the TTL value is decremented by 1 to the 0-system packet transmission unit 302. The 0-system packet transmitter 302 transfers the packet to the next receiving node 102 (S207). If the TTL value is “1” (Y in S206), the multicast packet is discarded because the TTL value becomes “0” when the TTL value is decremented by “1” (S208). The EoMPLS conversion unit 305 converts the MPLS packet into an Ethernet packet, and transfers the packet (query) to all the clients 112.

  If the packet determination unit 311 determines that the packet is not a multicast packet (N in S201), it determines whether the packet is addressed to the client 112 (S209). If the packet is addressed to the client 112 (Y in S209), The data is transferred to the EoMPLS conversion unit 305 (S211). If the packet is not addressed to the client 112 (N in S209), the packet is transferred to the 0-system packet transmitter 302 and transferred from the 0-system packet transmitter 302 to the next receiving node 102 (S210). Next, an operation example of the reception node 102 that receives a packet (report) that is an instruction to start reception of the multicast service from the client 112 will be described.

  The EoMPLS conversion unit 305 of the reception node 102 determines whether a packet (report) that is an instruction to start reception of the multicast service is received from the client 112. When the packet (report) is received, that is, when the client 112 receives the multicast service, the reception control unit 313 sets the TTL value 204 in the MPLS header 200 in advance in the system stored in the reception storage unit 314. In response to an instruction from the reception control unit 313, the EoMPLS conversion unit 305 receives the packet (report) of the Ethernet packet received from the client 112 in the MPLS header 200. Is converted to an MPLS packet packet (report) in which the TTL value “255” is set in the TTL value 204 of the packet, and the packet (report) that is an MPLS packet is transmitted to the ring-type MPLS network via the 1-system packet transmission unit 304. .

  As described in S002 and S004 of FIG. 6, the client 112 transmits a packet (report) to the receiving node 102 in response to the packet (query) received from the receiving node 102 (S002). There is a case where a packet (report) is spontaneously transmitted to the receiving node 102 (S004).

  Next, an operation example of the receiving node 102 that receives a packet (report) that is an instruction to stop receiving the multicast service from the client 112 will be described.

  The EoMPLS conversion unit 305 of the receiving node 102 determines whether a packet (report) that is an instruction to stop receiving the multicast service is received from the client 112. When the packet (report) is received, that is, when the client 112 stops receiving the multicast service and leaves the group of the multicast service, the reception control unit 313 stores the reception storage unit in the TTL value 204 in the MPLS header 200. The EoMPLS conversion unit 305 receives an instruction from the reception control unit 313 and receives the Ethernet packet received from the client 112 in response to an instruction to set “255” which is a predetermined TTL value in the system stored in 314. Packet (report) is converted to an MPLS packet packet (report) in which the TTL value 204 in the MPLS header 200 is set to the TTL value “255”, and the packet is sent to the ring MPLS network via the 1-system packet transmission unit 304. Packets that are MPLS packets To send door (the report).

  Although the multicast service distribution direction has been described as the 0-system direction, it is naturally possible to use the 1-system direction as the service distribution direction. In this case, both the transmission node 101 and the reception node 102 have necessary functional units as appropriate.

  According to the series of flows, in the new service distribution and the addition and stop processing of the service reception node, the setting value of the transmission TTL value 902 in the management table 900 of the transmission node 101 is the farthest receiving node 102 that receives the service. The multicast packet can be distributed until the farthest receiving node 102 is reached, and the multicast packet is discarded by TTL = 0 at the farthest end of the receiving node 102, so that useless communication bandwidth is suppressed.

  In addition, the receiving node 102 does not need to hold the management table 900 and only needs to perform relay and transfer processing according to the TTL value included in the received packet. Therefore, the process of referring to the management table at the time of relay and transfer processing And the management table update process does not occur, the processing load on the receiving node 102 can be reduced.

  In addition, since the transmission node 101 has the management table 900 that stores the transmission TTL value 902 calculated based on the number of transfer hops, each of the nodes 101 and 102 has the status of each node (position in the network). For example, it is possible to appropriately set a range in which multicast packets are to be distributed. Therefore, it is possible to reduce the processing load of the node and reduce the processing load of the entire network while effectively using the effective bandwidth without reducing the effective bandwidth of the network.

(Example 2)
A second embodiment will be described with reference to FIG. In this embodiment, not only service provision by one transmission node but also service provision by a plurality of nodes is performed. In this case, the node has the functions of a transmission node and a reception node at the same time, and this node is hereinafter referred to as “transmission / reception node 103”.

  FIG. 5 is an internal block configuration diagram of the transmission / reception node 103 to which the service distribution server 111 and the client 112 are connected. The transmission / reception control unit 315 has functional blocks of the transmission node 101 and the reception node 102 and controls the entire apparatus. The transmission / reception storage unit 316 stores the management table 900.

  The transmission / reception controller 315 also operates as a TTL calculator 310 that rewrites the management table 900 by calculating a distance (number of hops) from the receiving node that transmitted the packet (report) based on the TTL value of the received packet (report). Further, it distinguishes between the case of packet transmission for distributing a packet (query) or service from the service distribution server 111 and the case of transmitting a packet (report) from the client 112 to another transmission / reception node 103, and different instructions to the EoMPLS conversion unit 305. Put out.

  When the packet (query) is transmitted in an initial state where the other transmission / reception nodes 103 are not participating in the service, an instruction to add the initial TTL value 903 is issued to the EoMPLS conversion unit 305. In the case of service distribution from the service distribution server 111, an instruction to give a transmission TTL value 902 is issued to the EoMPLS conversion unit 305.

  When the client 112 transmits a packet (report), the client 112 issues an instruction to add an initial TTL value 903 to the EoMPLS conversion unit 305.

  As described above, the transmission / reception storage unit 316 has a function equivalent to the transmission storage unit 309, and the function equivalent to the reception storage unit 314 is realized by the initial TTL value 903.

  The specific operation of each transmission / reception node 103 is the same as that of the transmission node 101 and the reception node 102 of the first embodiment.

  An example of a management table in the case of providing a service by a plurality of transmission / reception nodes 103 is shown in FIG. Also, the distribution range of each service is shown in FIG.

  In this embodiment, by having a management table for each transmission node that provides each service, the transmission range of each service can be controlled by the TTL value.

  A multicast packet is transmitted to the farthest receiving desired node, and the multicast packet is discarded at the destination, so that the network bandwidth can be effectively used.

Further, since each node 103 has a management table of services provided by itself, there is no processing load such as management table updating due to an increase in the number of services of other nodes, and the processing load of the entire network can be reduced. (Example 3)
Embodiment 3 will be described with reference to FIG. This embodiment is an operation method for periodically transmitting a service start notification (query).

  When the service starts and during service provision, a service start notification (query) is transmitted from the transmission node 101 at regular intervals. The sending operation of the packet (query) by the sending node 101 is the same as in the first embodiment. When the client 112 receives the multicast service in response to the packet (query), the operation in which the receiving node 102 transmits the packet (report) to the service distribution server 111 is the same as in the first embodiment.

  On the other hand, when a client 112 receiving a new service joins a multicast service group, unlike the first embodiment, the client 112 does not send a packet (report) by itself, but periodically receives a packet (query). To respond.

  Since the service start notification (query) is periodically transmitted, the client 112 receiving the service periodically transmits a packet (report) in response to the packet (query) from the service distribution server 111. A client 112 that does not receive a service or wants to stop a service does not respond to a periodic packet (query) and does not transmit a packet (report).

  Therefore, the transmission TTL value 902 of the management table 900 of the transmission node 101 in which the service distribution server 111 is located is a TTL value that can periodically transmit the multicast packet to the receiving node 102 at the farthest end that receives the service, with the setting value updated periodically. It is possible to set with. Therefore, wasteful use of the communication band can be suppressed by discarding the multicast packet at the farthest receiving node 102 receiving the service.

  In addition, the receiving node 102 does not need to hold a management table, and it is only necessary to perform relay and transfer processing according to the TTL value included in the packet, so that the processing load can be reduced.

  The present invention is not limited to the above-described embodiments, and includes various modifications. 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. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment.

  Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment. Each of the above-described configurations, functions, processing units, processing means, and the like may be realized by hardware by designing a part or all of them with, for example, an integrated circuit such as an FPGA. Each of the above-described configurations, functions, and the like may be realized by software by interpreting and executing a program that realizes each function by the processor. Information such as programs, tables, and files for realizing each function may be placed in a recording device such as a memory, a hard disk, an SSD (Solid State Drive), or a recording medium such as an IC (Integrated Circuit) card, an SD card, or a DVD. it can.

  Further, the control lines and information lines indicate what is considered necessary for the explanation, and not all the control lines and information lines on the product are necessarily shown. Actually, it may be considered that almost all the components are connected to each other.

  Although the present invention has been described by taking the ring type MPLS as an example, the present invention can also be applied to other network shapes (for example, tree type), other network types (for example, Ethernet), and the like. With regard to the TTL concept, it can be applied to a communication method having a field representing the valid period of data, such as IPv6 Hop Limit.

101 transmission node 102 reception node 103 transmission / reception node 111 service providing server 112 client 301 system 0 packet reception unit 302 system 0 packet transmission unit 303 system 1 packet reception unit 304 system 1 packet transmission unit 305 Ethernet over MPLS conversion unit 306 TTL determination unit 307 Service determination unit 308 Transmission control unit 309 Transmission storage unit 310 TTL calculation unit 311 Packet determination unit 312 Multicast unit 313 Reception control unit 314 Reception storage unit 315 Transmission / reception control unit 316 Transmission / reception storage unit

Claims (11)

In a communication system that transmits and receives packets between a plurality of communication devices,
The communication device
A first transmitter for transmitting the packet;
A first control unit that controls each unit and causes the first transmission unit to transmit a packet having a lifetime area that is an area for storing a lifetime that decreases every time the packet is transferred by another communication device; ,
A first storage unit for storing an identifier for identifying a service distributed in a multicast packet for distributing a service and a first lifetime,
With
The other communication device is:
A second transmitter for transmitting the packet;
A second control unit that controls each unit and causes the second transmission unit to transmit a packet having the lifetime region;
A second storage unit that stores a second survival time that is the same value as the first survival time;
With
The first controller is
Causing the first transmitter to transmit a control multicast packet used for control with the other communication device that has assigned the first lifetime stored in the first storage to the lifetime region. ,
The second controller is
When the control multicast packet is received, the control packet used for control with the communication device having the second lifetime stored in the second storage unit in the lifetime area is transmitted to the second packet. 2 to the transmission unit,
The first controller is
When the control packet is received, the value of the survival time area is read from the received control packet, and the read value of the survival time area and the first survival time stored in the first storage unit Based on the above, a third lifetime that decreases every time a multicast packet that distributes the service is transferred by the other communication device is calculated, and the calculated third lifetime and the identifier are calculated. Is stored in the first storage unit, and a multicast packet for distributing the service with the third lifetime is assigned to the lifetime region is transmitted from the first transmitter. Communications system. The communication system according to claim 1,
The first controller is
Based on the read lifetime value and the first lifetime stored in the first storage unit, the number of times the control packet is transferred by the other communication device is calculated, A communication system, wherein the third survival time is calculated based on the calculated number of times. A communication system according to claim 2,
The first controller is
When the control packet is further received, the third lifetime is calculated from the received control packet, and the calculated third lifetime and the first storage unit stored in the first storage unit are calculated. The communication system is characterized in that the third survival time stored in the first storage unit is updated to the calculated third survival time according to a comparison with the 3 survival time. A communication system according to claim 3,
The first controller is
Further, as a result of comparison between the third survival time calculated from the received control packet and the third survival time stored in the first storage unit, it is stored in the first storage unit. When the calculated third survival time is larger than the calculated third survival time, the third survival time is updated to the calculated number of times. The communication system according to claim 4,
The control multicast packet transmitted by the communication device is:
A query packet inquiring whether or not the other communication device participates in a group that distributes multicast packets;
The control packet transmitted by the other communication device is:
A participation notification packet for notifying that the other communication device participates in the group that distributes the multicast packet;
The second controller is
When the query packet is received, the communication packet is transmitted from the second transmission unit. A communication system according to claim 2,
The control multicast packet transmitted by the communication device is:
A query packet inquiring whether or not the other communication device participates in a group that distributes multicast packets;
Among the other communication devices, the second control unit of the other communication device participating in the group that distributes the multicast packet,
As the control packet, the second transmission unit transmits a leave notification packet for notifying that the multicast packet is to be separated from the group that delivers the multicast packet,
The first controller is
When further receiving the leave notification packet, the third life time calculated from the leave notification packet is compared with the third life time stored in the first storage unit, and from the leave notification packet When the calculated third survival time and the third survival time stored in the first storage unit have the same value, the third survival time calculated from the withdrawal notification packet or the first A communication system, characterized by causing the first transmitter to transmit the control multicast packet to which any of the third lifetimes stored in a storage unit is assigned. The communication system according to claim 6,
The first controller is
When the control transmission packet to which the third lifetime is given is transmitted to the first transmitter, the third lifetime stored in the first storage is updated to a predetermined value. A communication system characterized by the above. A transmission unit that transmits a packet having a lifetime area that is an area for storing a lifetime that decreases every time it is transferred by another communication device;
A storage unit for storing an identifier for identifying a service to be distributed in a multicast packet for distributing the service and a first lifetime,
A control multicast packet used for control with the other communication device assigned the first survival time to the survival time region is transmitted to the transmission unit, and a control packet including the survival time region is transmitted. Upon receipt, the value of the lifetime field is read from the received control packet, and the service is distributed based on the read lifetime value and the first lifetime stored in the storage unit. A second lifetime that decreases every time a multicast packet to be transferred is transferred by the other communication device, and stores the calculated second lifetime and the identifier in association with each other. And a control unit that causes the transmission unit to transmit a multicast packet that distributes the service in which the second lifetime is assigned to the lifetime region,
A communication apparatus comprising: The communication device according to claim 8,
The controller is
When the control packet is further received, it is determined whether or not the identifier stored in the storage unit is included in the received control packet, and the identifier stored in the storage unit is included The second lifetime is calculated from the received control packet, and the calculated second lifetime and the second lifetime stored in the storage unit in association with the identifier are calculated. In comparison, when the second survival time calculated is larger than the second survival time stored in the storage unit, the second survival time stored in the storage unit is calculated. The communication apparatus is updated to the second lifetime. The communication device according to claim 8,
The controller is
When the control packet is further received, it is determined whether or not the identifier stored in the storage unit is included in the received control packet, and the identifier stored in the storage unit is included The second lifetime is calculated from the received control packet, and the calculated second lifetime and the second lifetime stored in the storage unit in association with the identifier are calculated. In comparison, when the second survival time calculated and the second survival time calculated are the same value, the second survival time stored in the storage unit is given. A communication apparatus that causes the transmitting unit to transmit the multicast packet for control. The communication device according to claim 8,
The received control packet is
The other communication device transmits a second survival time having the same value as the first survival time to the survival time region.

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