JP4800916B2 - Data relay device - Google Patents

Description

  The present invention relates to a data relay device that relays data of multicast data.

  There is a multicast communication network as a communication system that designates a plurality of partners on a network and transmits the same data. As this multicast communication network, for example, a layer 2 including a multicast router, one to a plurality of layer 2 switches connected to the multicast router, and a terminal (multicast receiving terminal) connected to the layer 2 switch. There is a network.

  In general multicast, a multicast packet is flooded on the layer 2 network and relayed throughout the layer 2 network. Each device that has received the multicast packet selectively receives the multicast packet. For this reason, multicast data traffic on the layer 2 network increases.

  As a technique for reducing multicast data traffic on a layer 2 network, there is a method of applying a snooping switch to a layer 2 switch. The snooping switch (layer 2 switch) identifies (analyzes) the content of the received packet when a packet including a multicast reception request message (Query message) is received. The snooping switch analyzes a packet of a multicast membership management protocol (for example, RFC3376 IGMPv3 or RFC3810 MLDv2) exchanged between a multicast router and a terminal, for example. Further, the snooping switch records the multicast group IP address and message reception port included in the received message. When a multicast packet addressed to the recorded multicast group IP address arrives, the multicast packet is distributed (data relayed) to the recorded port.

  In this way, the snooping switch reduces unnecessary multicast data traffic by selectively relaying data on the layer 2 network without relaying multicast packets to ports that have not received the multicast reception request message. ing.

  However, when the layer 2 network becomes larger and the number of terminals increases, even if a snooping switch is applied to the layer 2 network and a multicast membership management protocol is used, the amount of data flowing in the layer 2 network is reduced. Increase. That is, for example, in a layer 2 network including a layer 2 switch having an IGMP / MLD snooping function, a multicast router transmits a query message for managing multicast group membership, and the layer 2 switch transmits the query message to all ports. Relay to Each terminal participating in the multicast group transmits a multicast reception response message (Report message) in response to the Query message. When the layer 2 switch receives the report message, it learns the content and relays the report message to the port on the multicast router 30 side.

  For this reason, if there are a large number of receiving terminals in the layer 2 network, a large number of Report messages will be concentrated on the ports of the multicast router. This consumes a large amount of link bandwidth in the vicinity of the multicast router and increases the processing load on the multicast router for packet reception.

  In the communication system described in Non-Patent Document 1, the layer 2 switch aggregates multicast receiver connection information recorded at a plurality of ports on the downstream side (terminal connection side), and the source address is an undetermined address (0.04 if IPv4). .0.0, IPv6 (: :)), a multicast reception request message (Query message) is generated and a proxy response function that transmits the message to the upstream side (router connection side) port is suggested.

  In the communication system described in Non-Patent Document 2, the proxy device terminates the IGMP / MLD message exchange, operates as a host for the upstream where the multicast router exists, and for the downstream where the receiving host exists. Operates as a router.

  Thus, in Non-Patent Documents 1 and 2, the layer 2 switch of the communication system has an IGMP snooping function that can aggregate multicast receiver connection information. Then, the Query message transmitted from the multicast router is terminated at the layer 2 switch (the most upstream switch) connected to the multicast router on the downstream side. This most upstream layer 2 switch generates a report message based on the aggregated receiver information of its own device and transmits it to the multicast router. As a result, the multicast router confirms the presence of the receiving terminal. Further, the most upstream layer 2 switch generates a Query message as necessary and transmits it to the downstream side of its own device. At this time, for example, an undetermined address is used as the source address of the IP packet. Other layer 2 switches (switches on the downstream side of the most upstream layer 2 switch) operate in the same manner as the most upstream layer 2 switch.

  Further, in the layer 2 switch described in Patent Document 1, multicast users connected under the layer 2 switch arranged between the user terminal connected by P2P and the packet transfer apparatus are managed in the access carrier network. It has a function. Then, the layer 2 switch receives the multicast packet on behalf of the subordinate user terminal and copies and distributes it, thereby suppressing the bandwidth consumption between the layer 2 switch and the packet transfer apparatus.

M. Chiristensen, 2 others, RFC4541 “Considerations for Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Snooping Switches” 2006 Page 4. B. Fenner, 3 others RFC 4605 "Internet Group Management Protocol (IGMP) / Multicast Listener Discovery (MLD) -Based Multicast Forwarding" ("IGMP / MLD Proxying") 2006 JP 2006-109047 A

  However, in the first prior art (RFC4541), a specific method for realizing the proxy function is not shown, and multicast using the proxy function cannot be realized. In addition, when the layer 2 switch uses the undetermined address as the source address when transmitting the Query message to the terminal device, it is uncertain whether the terminal device will process the Query message as a normal packet. For this reason, when a terminal device that does not process a Query message whose source address is an undetermined address as a normal packet is connected, there is a problem that multicast cannot be performed normally. Even if a device-specific IP address is used as a source address, there is a problem that address management becomes complicated because it is necessary to perform address assignment so as not to participate in the query transmission router selection process of the IGMP / MLD router. It was.

  Further, in the second prior art (RFC 4605), it is necessary to explicitly set the upstream I / F and the downstream I / F, and there is a problem that a configuration in which a router or a terminal is connected in an arbitrary direction cannot be applied. there were.

  Further, the third prior art has a problem that the control message itself cannot be reduced and multicast data traffic cannot be reduced on the network.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a data relay apparatus that performs multicast communication easily and efficiently with a simple configuration.

In order to solve the above-described problems and achieve the object, the present invention is configured to perform multicast relay by snooping messages transmitted and received between a multicast router and a receiving terminal used in a layer 3 multicast membership management protocol. In the data relay apparatus to be controlled, a terminal side communication unit that transmits / receives a message to / from the receiving terminal side at an interface for each receiving terminal, a router side communication unit that transmits / receives a message to / from the multicast router side, and participation in multicast Alternatively, a message indicating departure from the multicast is transmitted to the multicast router, and an inquiry message for inquiring about the multicast transmitted from the multicast router is relayed to the receiving terminal side, and the multicast router is relayed. Controls multicast forwarding between multicast forwarding and the receiving terminal between Toruta side, and collects the recipient information on the receiving terminal based on the response message from said receiving terminal to said inquiry message, collect A communication control unit that controls the multicast relay using the received receiver information, and the receiver information includes multicast information related to the multicast entry corresponding to each interface and a timer of a management timer that manages each multicast entry The communication control unit, when receiving from the multicast router side a confirmation message for confirming a receiver to be separated from the inquiry message, the communication control unit sends the confirmation message based on each timer value. Determine whether to relay, If it is determined that relays serial withdrawal confirmation message, characterized in that it relays the withdrawal confirmation message from the interface which corresponds to the timer value is determined to relaying the withdrawal confirmation message.

  According to the present invention, the receiver information about the receiving terminal is collected based on the response message from the receiving terminal to the inquiry message, and the multicast relay is controlled using the collected receiver information. There is an effect that multicast communication can be performed well.

  Hereinafter, embodiments of a data relay device according to the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a configuration of a communication network having a layer 2 switch according to Embodiment 1 of the present invention. The communication network 1 is a multicast communication network that designates a plurality of partners on the network and transmits the same data, and includes a layer 2 switch 10, a multicast router 30, and terminal devices (receiving terminals) 20J to 20L.

  The layer 2 switch (data relay device) 10 is disposed between the multicast router 30 and the terminal devices 20J to 20L, and snoops data (messages) transmitted and received between the multicast router 30 and the terminal devices 20J to 20L. Data relay (multicast relay control).

  The layer 2 switch 10 is connected to the terminal device 20J through the I / F unit 11J, is connected to the terminal device 20K through the I / F unit 11K, and is connected to the terminal device 20L through the I / F unit 11L. The layer 2 switch 10 is connected to the multicast router 30 by the I / F unit 16.

  The layer 2 switch 10 relays a Query message (multicast reception request message) 51 sent from the multicast router 30 to the terminal devices 20J to 20L and reports a Report message (Query) sent from a predetermined terminal device (for example, the terminal device 20J). A multicast reception response message) to the multicast router 30 is relayed. Further, the layer 2 switch 10 relays a multicast data packet (multicast data for the Report message) transmitted from the multicast router 30 to a predetermined terminal device (reception side).

  Here, a case is shown in which the layer 2 switch 10 relays the Query message 51 from the multicast router 30 to the terminal devices 20J to 20L and relays the Report message 52 from the terminal device 20J to the multicast router 30. Here, a case is shown in which the layer 2 switch 10 relays the multicast data packet 53 from the multicast router 30 to the terminal device 20J.

  In the following description, it is assumed that there are terminal devices 20J to 20L that support IGMPv1 / v2 or MLDv1 as multicast receivers. Here, the case where the communication network 1 is configured to include one layer 2 switch 10 has been described. The communication network 1 may be configured to include a plurality of layer 2 switches 10. In this case, the layer 2 switches 10 are connected to each other and are disposed between the multicast router 30 and the terminal devices 20J to 20L.

  FIG. 2 is a block diagram showing the configuration of the layer 2 switch according to Embodiment 1 of the present invention. The layer 2 switch 10 includes an I / F unit (terminal side communication unit) 11J to 11L, a router mode reception unit 12J to 12L, a multicast table storage unit 13J to 13L, a reception group management table storage unit 14, a query reception processing unit 15, An I / F unit (router side communication unit) 16 is provided. The router mode receiving units 12J to 12L and the Query reception processing unit 15 here correspond to the communication control unit described in the claims.

  The I / F units 11J to 11L are communication interfaces connected to the terminal devices 20J to 20L, respectively, and the I / F unit 16 is a communication interface connected to the multicast router 30.

  The router mode receiving unit 12J is connected to the I / F unit 11J and performs a router mode operation on the connection destination (terminal device 20J) of the I / F unit 11J. The router mode receiving unit 12K is connected to the I / F unit 11K and performs a router mode operation on the connection destination (terminal device 20K) of the I / F unit 11K. The router mode receiving unit 12L is connected to the I / F unit 11L and performs a router mode operation on the connection destination (terminal device 20L) of the I / F unit 11L.

  The multicast table storage unit 13J is connected to the router mode receiving unit 12J and stores a multicast table (multicast table of the I / F unit 11J) that manages the multicast state (multicast information) of the I / F unit 11J.

  The multicast table storage unit 13K is connected to the router mode receiving unit 12K and stores a multicast table (multicast table of the I / F unit 11K) that manages the multicast state of the I / F unit 11K.

  The multicast table storage unit 13L is connected to the router mode reception unit 12L and stores a multicast table (multicast table of the I / F unit 11L) that manages the multicast state of the I / F unit 11L.

  Each entry in each multicast table has fields of a multicast address, an entry timer (an entry timer for each I / F portion of the multicast entry), a source list, a source timer, an exclusion list, and a filter timer.

  The multicast address is an address used when relaying a multicast packet. The entry timer is a timer used for managing a multicast table (multicast entry) for each I / F unit, and is used for determining whether an entry of each I / F unit is valid or invalid. The source list is a list of source addresses from which multicast packets are transmitted. The source timer is a timer used for managing the source list, and is used for determining whether the source list is valid or invalid. The exclusion list is a list of source addresses of sources for which the recipients (terminal devices 20J to 20L) are requesting exclusion. The filter timer is a timer used for managing the exclusion list, and is used for determining whether the exclusion list is valid or invalid.

  The reception group management table storage unit 14 is connected to the multicast table storage units 13J to 13L and stores a reception group management table. Here, the reception group management table is a data table of information on the I / F units 11J to 11L connected to the receiver for each multicast group address (data table for managing each I / F unit).

  Each entry in the reception group management table has fields of a multicast address, a destination I / F list, an entry timer, a source list, and an exclusion list. The entry timer here is a timer used for managing the multicast address entry, and is used for determining whether the multicast address entry is valid or invalid.

  The query reception processing unit 15 is connected to the reception group management table storage unit 14, the I / F units 11J to 11L, and the I / F unit 16. The Query reception processing unit 15 performs a host mode operation for each of the I / F units 11J to 11L.

  2 shows the configuration of the layer 2 switch 10 in the case where the multicast router 30 exists ahead of the I / F unit 16, the multicast router exists also ahead of each I / F unit 11J to 11L. Therefore, a router mode reception unit and a query reception processing unit may be prepared for all I / F units.

  The reception group management table and the multicast table for each I / F unit correspond to the recipient information described in the claims. An entry timer, a source timer, and a filter timer correspond to the management timer described in the claims.

  Next, an operation procedure of the layer 2 switch according to the first embodiment will be described. In the communication network 1, the multicast router 30 transmits a general query message (inquiry message) at a predetermined cycle, and the layer 2 switch 10 receives the general query message at the I / F unit 16. The General Query message includes a query interval, a query response interval, and a reliability variable (Robustness Variable). The layer 2 switch 10 receives these values. This is stored in the table storage unit 14.

  FIG. 3 is a flowchart illustrating an operation procedure of the query reception processing unit when the layer 2 switch according to the first embodiment receives the general query message, and FIG. 4 is a flowchart illustrating the operation of the layer 2 switch according to the first embodiment. It is a flowchart which shows the operation | movement procedure of a router mode receiving part at the time of receiving a message.

  When the I / F unit 16 of the layer 2 switch 10 receives the general query message (step S100), it transfers the general query message to the query reception processing unit 15.

  The query reception processing unit 15 searches the reception group management table in the reception group management table storage unit 14 and confirms whether or not a multicast address entry corresponding to the general query message exists in the reception group management table (step S1). S110).

  When there is no multicast address entry (step S110, no entry), the Query reception processing unit 15 receives each I / F unit (I / F) other than the I / F unit (I / F unit 16) that has received the general query message. The general query message is relayed via the sections 11J to 11L (step S120). For example, until the layer 2 switch 10 receives a report message for the general query message from the terminal devices 20J to 20L and generates a multicast address entry for the terminal devices 20J to 20L, the terminal from each I / F unit 11J to 11L The general query message is relayed to the devices 20J to 20L. Here, since the Report message for the General Query message has not yet been received from the terminal devices 20J to 20L, the General Query message is relayed to the terminal devices 20J to 20L. Thus, when there is no multicast address entry corresponding to the general query message in the reception group management table, the general query message is relayed to the terminal devices 20J to 20L.

  When a multicast receiver (terminal device) exists on the communication network 1, the multicast receiver (terminal device) responds to the General Query message with a Report message. Here, a case will be described in which the terminal apparatus 20J responds to the General Query message with a Report message, and the I / F unit 11J of the layer 2 switch 10 receives the Report message. When receiving the Report message from the terminal device 20J, the I / F unit 11J transfers the Report message to the router mode receiving unit 12J.

  Here, an operation process of the router mode receiving units 12J to 12L when the Report message is received will be described. Since router mode receivers 12J to 12L perform the same operation, the operation procedure of router mode receiver 12J will be described with reference to FIG.

  FIG. 4 shows an operation procedure when the layer 2 switch 10 receives a report message of a group membership management protocol that does not involve source designation such as IGMPv1, IGMPv2, and MLDv1.

  When the router mode receiving unit 12J receives the report message via the I / F unit 11J (step S200), it is included in the report message from the multicast table (multicast table of the I / F unit 11J) in the multicast table storage unit 13J. A multicast address is searched (step S210).

  When there is no entry corresponding to the multicast address of the Report message in the multicast table in the multicast table storage unit 13J (step S210, no entry), the router mode receiving unit 12J determines that the multicast entry (I / F) corresponding to the Report message (Multicast entry of unit 11J) is generated in the multicast table (step S220). Here, since the I / F unit 11J receives the Report message for the first time from the terminal device 20J, a multicast entry corresponding to the I / F unit 11J (terminal device 20J) is generated.

  After generating the multicast entry, the router mode receiving unit 12J activates the entry timer of the I / F unit 11J as an entry timer for each I / F unit (step S230). The entry timer here uses MALI (Multicast Address Listening Interval) (sum of question interval and reliability variable and sum of question response time) as the initial value of the entry timer, and subtracts the timer value as time passes. MALI is a multicast reception interval and a time until timeout (amount of time that must be waited before determining that there is no receiver).

  Further, the router mode receiving unit 12J searches for the multicast address included in the Report message from the reception group management table in the reception group management table storage unit 14 (step S240).

  When there is no entry corresponding to the multicast address in the reception group management table in the reception group management table storage unit 14 (step S240, no entry), the router mode reception unit 12J generates a new entry in the reception group management table. And register. Specifically, a new multicast address and information (destination I / F) of the I / F unit 11J that received the Report message are set in the reception group management table and stored in the reception group management table storage unit 14 ( Step S250).

  Here, since the I / F unit 11J receives a Report message for the first time from the terminal device 20J, the router mode receiving unit 12J sets a new entry in the reception group management table.

  The Query reception processing unit 15 generates a Report message based on the newly generated entry in the reception group management table. The generated Report message is transmitted to the connection port of the multicast router 30 (hereinafter referred to as router connection port) via the I / F unit 16 (step S260). At this time, the entry timer value of the new entry (multicast address entry in the reception group management table) is set to MALI (step S270).

  On the other hand, if there is an entry corresponding to the multicast address in the reception group management table in the reception group management table storage unit 14 in the process of step S240 (step S240, there is an entry), the router mode reception unit 12J performs the reception group management. The I / F unit 11J that received the Report message is added to the destination I / F in the table (step S280). Then, the entry timer of the multicast address entry in the reception group management table is updated to MALI (step S270).

  The router connection port receives an I / F unit (I / F unit) that receives a Query message or a protocol packet (such as a PIM Hello packet defined by RFC4601 or an MRD message defined by RFC4286) transmitted by the multicast router 30. 16) is set by learning, or is defined by setting by an administrator.

  The Report message transmitted from the router connection port arrives at the multicast router 30. As a result, the multicast router 30 starts relaying the multicast packet addressed to the multicast address included in the Report message.

  In the layer 2 switch 10, when a multicast packet from the multicast router 30 is received by the I / F unit 16, the Query reception processing unit 15 refers to the reception group management table and extracts an entry corresponding to the destination multicast address. The Query reception processing unit 15 relays the multicast packet to the I / F unit (here, the I / F unit 11J) defined as the destination I / F in the extracted entry.

  In this way, since multicast packets are not relayed to I / F units other than the I / F unit 11J (I / F units that have not received a Report message), unnecessary traffic is relayed to an interface where no multicast receiver exists. It will never be done. As a result, unnecessary traffic relaying can be prevented.

  Next, after the layer 2 switch 10 sets information about the multicast receiver (multicast entry of the I / F unit 11J), the multicast router 30 receives the general query transmitted at the query interval cycle by the I / F unit 16. The operation of will be described with reference to FIG.

  When the I / F unit 16 of the layer 2 switch 10 receives the general query message (step S100), it transfers the general query message to the query reception processing unit 15.

  The query reception processing unit 15 searches the reception group management table in the reception group management table storage unit 14 and confirms whether or not a multicast address entry corresponding to the general query message exists in the reception group management table (step). S110).

  Here, since the report address has already been received from the terminal device 20J and the multicast address entry has been created in the reception group management table, the multicast address entry (the I / F unit that received the report message has been received in the reception group management table). 11J information) exists. If there is a multicast address entry (step S110, there is an entry), the Query reception processing unit 15 checks the entry timer value of this multicast address entry (step S130).

  If the entry timer value is larger than LLQT (Last Listener Query Time) (product of question response time and reliability variable) (step S130,> LLQT), the Query reception processing unit 15 reports using the multicast address of the multicast address entry. Generate a message. At this time, the source address of the generated Report message packet is set as an undetermined address. Note that the LLQT (threshold value) here is a time for waiting for a response from the last inquiry time (maximum response waiting time of an inquiry message).

  The generated Report message is transmitted to the router connection port (step S140). That is, from a recipient whose entry timer value is greater than LLQT and whose entry is unlikely to be deleted from the multicast address entry, a report message with the source address as an undetermined address is sent to the multicast router 30 without waiting for reception of the report message. Send it to. Thereby, the Query reception processing unit 15 relays the General Query message to the receiver corresponding to the entry whose entry timer value is larger than LLQT and does not wait for the reception of the Report message sent from this receiver. Report message is being sent to.

  The multicast router 30 is set to process the Report message as a normal message even if the source address of the Report message is an undetermined address. For example, the multicast router 30 is defined by a standard such as RFC3376. Receiving the Report message, the multicast router 30 confirms the presence of the recipient of the multicast address included in the Report message, and continues relaying the multicast packet.

  Thus, for an entry whose entry timer value is larger than LLQT, the Query reception processing unit 15 transmits a Report message to the multicast router 30 without waiting for reception of a Report message sent from the receiver. The multicast router 30 can quickly determine whether or not to continue relaying multicast packets for recipients whose entries have an entry timer value larger than LLQT.

  On the other hand, if the entry timer value is less than or equal to LLQT (step S130, ≦ LLQT), it is determined that the entry is a recipient entry that is likely to be deleted from the multicast address entry, and a report message is sent to the multicast router 30. Is not generated. Thereafter, when a Report message is not transmitted from a recipient who is likely to delete an entry from the multicast address entry, transmission of the Report message corresponding to this recipient to the multicast router 30 can be omitted.

  Thereafter, the Query reception processing unit 15 searches the reception group management table to check whether or not the next multicast address entry (another multicast address entry) exists in the reception group management table (step S110). The query reception processing unit 15 performs the processing of steps S130 and S140 for all the multicast address entries in the reception group management table.

  When the processing of steps S130 and S140 is performed for all multicast address entries in the reception group management table, it is determined that there are no remaining multicast address entries in the reception group management table (step S110, no entry). Then, the general query message received by the I / F unit 16 is relayed to all the ports on the terminal devices 20J to 20L via the I / F units 11J to 11L other than the I / F unit 16 (step S120). .

  If a multicast receiver exists ahead of the I / F units 11J to 11L, a report message is returned from the multicast receiver (terminal device) to the relayed general query message. Here, since the terminal device 20J that is a multicast receiver exists ahead of the I / F unit 11J, a Report message is returned from the terminal device 20J to the relayed General Query message. The Report message from the terminal device 20J is received by the I / F unit 11J and transferred to the router mode receiving unit 12J.

  Here, an operation procedure when the router mode receiving unit 12J receives the Report message after setting the multicast address entry in the multicast table will be described with reference to FIG.

  When receiving the Report message via the I / F unit 11J (Step S200), the router mode receiving unit 12J searches for the multicast address included in the Report message from the multicast table in the multicast table storage unit 13J (Step S210).

  When there is an entry corresponding to the multicast address in the multicast table in the multicast table storage unit 13J (step S210, there is an entry), the router mode receiving unit 12J sets the entry timer value for each I / F unit (in the I / F unit 11J). (Entry timer value) is updated to MALI (step S290).

  Then, the router mode reception unit 12J confirms the entry timer value of the multicast address entry in the reception group management table (step S300). If the entry timer value of the multicast address entry exceeds LLQT (step S300,> LLQT), the entry timer value of the multicast address entry is updated to MALI (step S270).

  On the other hand, when the entry timer value of the multicast address entry is a value equal to or smaller than LLQT (step S300, ≦ LLQT), since the processing of step S140 (generation and transmission of the report message) is not performed, the query reception processing unit 15 Generate a Report message. The generated Report message is transmitted to the router connection port via the I / F unit 16 (step S260). Then, the entry timer value of the multicast address entry in the reception group management table is updated to MALI (step S270). In a state where any one of the receivers (terminal devices 20J to 20L) is continuously participating in the multicast, the layer 2 switch 10 periodically executes the operations of FIG. 3 and FIG.

  Next, an operation procedure of the layer 2 switch 10 when the receiver explicitly sends a Leave message (leave request message) to leave the multicast while the receiver is participating in the multicast will be described. Here, a case where the terminal device 20J leaves the multicast will be described.

  When the terminal device 20J that is a receiver leaves the multicast, the terminal device 20J transmits a Leave message that stores the multicast group address. When receiving the Leave message from the terminal device 20J, the I / F unit 11J transfers the message to the router mode receiving unit 12J. Then, the router mode receiving unit 12J sets the entry timer (entry timer of the I / F unit 11J) value of the entry corresponding to the terminal device 20J in the multicast table of the multicast table storage unit 13J to a value (threshold value) equal to or less than LLQT. To shorten. The entry timer value set here serves as a threshold for determining whether to transmit a Report message or to determine whether to relay a Query message.

  At this time, the router mode receiving unit 12J obtains the largest entry timer value among the entries of the same multicast group address possessed by other I / F units (I / F units 20K and 20L). Then, the acquired entry timer value is set in the entry timer of the multicast address entry in the reception group management table. When only the I / F unit 11J that has received the Leave message has an entry for the multicast group address, the entry timer for the multicast address entry in the reception group management table is also changed to LLQT.

  The router mode receiving unit 12J generates a Leave message using the multicast group address of the entry and transmits it to the router connection port when the entry timer value of the multicast address entry in the reception group management table is updated to LLQT or less. To do.

  When receiving the Leave message, the multicast router 30 updates the entry timer for the multicast group address indicated in the Leave message to LLQT, and transmits a Specific Query message (a message for confirming the leaving receiver).

  In addition, in anticipation of the time until the Specific Query message is transmitted from the multicast router 30 in response to the Leave message and arrives at the Layer 2 switch 10, the Layer 2 switch 10 sets the entry timer determination threshold for the Leave message transmission to be larger than the LLQT. It is good also as a value (value according to a time lag).

  When receiving the Specific Query message from the multicast router 30, the I / F unit 16 of the layer 2 switch 10 transmits this message to the Query reception processing unit 15.

  Here, an operation procedure when the Query reception processing unit 15 receives the Specific Query message will be described. FIG. 5 is a flowchart illustrating an operation procedure of the query reception processing unit when the layer 2 switch according to the first embodiment receives the specific query message.

  FIG. 5 shows an operation when a Specific Query message of a group membership management protocol such as IGMPv1, IGMPv2, or MLDv1, which is not accompanied by a source designation, is received.

  When receiving the Specific Query message (step S400), the I / F unit 16 of the layer 2 switch 10 transfers the Specific Query message to the Query reception processing unit 15.

  The query reception processing unit 15 searches the reception group management table in the reception group management table storage unit 14. The Query reception processing unit 15 checks whether or not there is a multicast address entry corresponding to the multicast group address indicated by the Specific Query message in the reception group management table (Step S410).

  When the multicast address entry of the multicast group address indicated by the Specific Query message exists in the reception group management table (step S410, there is an entry), the Query reception processing unit 15 checks the entry timer value of the multicast address entry (step S410). S420).

  When the entry timer value of the multicast address entry is larger than LLQT (step S420,> LLQT), the Query reception processing unit 15 generates a Report message using the multicast address of the multicast address entry and transmits it to the router connection port ( Step S430).

  As a result, the multicast router 30 can quickly determine whether or not the entry has a larger entry timer value than the LLQT, whether or not it is a receiver that leaves the multicast.

  On the other hand, when the entry timer value of the multicast address entry is less than or equal to LLQT (step S420, ≦ LLQT), the Query reception processing unit 15 does not generate a Report message.

  That is, if the entry timer value is equal to or less than LLQT, it is determined that the entry is a recipient entry that is likely to be deleted from the multicast address entry, and a Report message to the multicast router 30 is not generated. As a result, when a report message for a specific query message is not transmitted from a recipient who is likely to delete an entry from the multicast address entry, transmission of the report message corresponding to this recipient to the multicast router 30 can be omitted. It becomes.

  In this embodiment, when the router mode receiving unit 12J receives the Leave message from the terminal device 20J, the entry timer value of the I / F unit 11J is shortened to LLQT. Less than. For this reason, the Query reception processing unit 15 does not transmit a Report message.

  The Query reception processing unit 15 sends a specific query message to each of the I / F units having an entry that is instructed by the Specific Query message and has an entry timer value for each I / F unit equal to or less than LLQT. Is relayed (step S440).

  In other words, an I / F unit that does not have an entry for the designated multicast address, or an I / F unit whose entry timer value for each I / F unit in the multicast table (multicast entry) for each I / F unit is larger than LLQT. Does not relay the Specific Query message. Accordingly, it is possible to reduce the amount of the specific query message that is relayed to the query reception processing unit 15 and flows in the communication network 1 and the amount of the report message that is responded to by the terminal device in response to the specific query message. .

  If there is no receiver ahead of the I / F part that relays the Specific Query message, the Report message is not responded to the Specific Query message. For this reason, the entry timer of the multicast entry of the I / F unit that did not respond to the Report message and the entry timer of the reception group management table (multicast address entry) expire. As a result, the Query reception processing unit 15 deletes each entry whose entry timer has expired from the reception group management table and stops relaying the multicast packet.

  Further, the multicast router 30 stops relaying the multicast packet due to a timeout due to not receiving the Report message, and stops the inflow of the multicast packet into the communication network 1.

  On the other hand, when there is a receiver ahead of the I / F unit that relays the Specific Query message and a Report message for the Specific Query message is returned from the receiver, it is received by the I / F unit 11J. This Report message is transferred to the router mode receiving unit 12J.

  The operation procedure of the router mode receiving unit 12J when receiving the Report message for the Specific Query message will be described with reference to FIG. Here, a case will be described where a Report message for the Specific Query message is transmitted from the terminal device 20J.

  When receiving the Report message via the I / F unit 11J (Step S200), the router mode receiving unit 12J searches for the multicast address included in the Report message from the multicast table in the multicast table storage unit 13J (Step S210).

  When there is an entry corresponding to the multicast address in the multicast table in the multicast table storage unit 13J (step S210, there is an entry), the router mode receiving unit 12J sets the entry timer value for each I / F unit (in the I / F unit 11J). (Entry timer value) is updated to MALI (step S290).

  Then, the router mode reception unit 12J confirms the entry timer value of the multicast address entry in the reception group management table (step S300). If the entry timer value of the multicast address entry exceeds LLQT (step S300,> LLQT), the entry timer value of the multicast address entry is updated to MALI (step S270).

  On the other hand, if the entry timer value of the multicast address entry is equal to or less than LLQT (step S300, ≦ LLQT), the processing of step S430 (generation and transmission of the report message) is not performed, so the query reception processing unit 15 reports Generate a message. The generated Report message is transmitted to the router connection port via the I / F unit 16 (step S260). Then, the entry timer value of the multicast address entry in the reception group management table is updated to MALI (step S270). When receiving the Report message, the multicast router 30 updates the entry timer to MALI and continues the multicast relay.

  Thereby, the layer 2 switch 10 stops the multicast relay to the I / F unit accommodating the receiver when an arbitrary receiver withdraws (disappears), but the multicast to other I / F units Will continue.

  As described above, according to the first embodiment, the multicast table and the reception group management table for each I / F unit are generated and updated based on the Report message transmitted from the terminal device, and the I / F unit is updated. Since message relaying is performed using a multicast table and a reception group management table, multicast using a proxy function can be realized.

  In addition, since the presence / absence (necessity) of the forwarding of the specific query message is determined with reference to the entry timer value of the multicast table entry for each I / F part, unnecessary message relaying can be eliminated, and the control message Exchange traffic can be reduced.

  Also, when the entry timer value of the multicast address entry in the reception group management table is LLQT or less, the Report message to the multicast router 30 for the Specific Query message or the General Query message is not performed, and the entry timer value is updated from LLQT or less Since the report message transmission condition is changed to a value exceeding LLQT, only the minimum necessary report message is transmitted to the multicast router 30, and control message exchange traffic can be reduced.

  Therefore, the number of messages flowing through each link in the communication network 1 is reduced, and it is possible to efficiently perform multicast group membership management protocol exchange.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment, when a receiver in INCLUDE mode transmits a BLOCK type report message for deleting an arbitrary source from the source list, a report message is transmitted to the multicast router 30 based on the change in the source timer value. Judge whether to do.

  FIG. 6 is a diagram showing a configuration of a communication network having a layer 2 switch according to Embodiment 2 of the present invention. Among the constituent elements in FIG. 6, constituent elements that achieve the same functions as those of the communication network 1 of the first embodiment shown in FIG. 1 are given the same numbers, and redundant descriptions are omitted.

  The layer 2 switch 40 is the same switch as the layer 2 switch 10. The layer 2 switch 40 is connected to the terminal device 20J by the I / F unit 11J, and is connected to the layer 2 switch 10 by the I / F unit 16.

  The layer 2 switch 10 is connected to the layer 2 switch 40 by the I / F unit 11J, is connected to the terminal device 20L by the I / F unit 11L, and is connected to the multicast router 30 by the I / F unit 16.

  Here, a case is shown in which the Report message 31 from the terminal device 20K is relayed in the order of the layer 2 switch 40 and the layer 2 switch 10 and sent to the multicast router 30. Here, the layer 2 switch 10 relays the multicast data packet 35 from the multicast router 30 to the layer 2 switch 40, and the layer 2 switch 40 relays the multicast data packet 35 from the layer 2 switch 10 to the terminal device 20K. Shows the case.

  In the following description, it is assumed that the communication network 1 supports IGMPv3 or MLDv2 as a multicast receiver and there are terminal devices 20J to 20L that can also specify a source address.

  The terminal devices 20J to 20L that can specify these source addresses include, in the Report message, a multicast group address that the device itself wants to participate in and a list of source addresses that are IP addresses of the transmission source devices (source address list). And the filter mode, and notifies the layer 2 switches 10 and 40 of these pieces of information. Among these, the filter mode is information indicating whether the source address list is a target for requesting reception or excluded from reception.

  For example, in the case of the filter mode INCLUDE (A) with the multicast address M, the source address included in the source list A is set as the transmission source, and the transmission source is requested to receive the multicast packet of the destination M.

  Further, in the case of the filter mode EXCLUDE (X, Y) with the multicast address M, the source address other than the source address included in the source list Y is set as the transmission source, and this transmission source is requested to receive the multicast packet of the destination M. is there.

  Here, the X is called a “request list”, and is a source list listing sources that are starting the source timer. Y is referred to as an “exclusion list”, and is a source list that lists sources from which the recipient requests exclusion.

  The multicast router 30 here also periodically transmits a general query message, similarly to the multicast router 30 of the first embodiment. The layer 2 switches 10 and 40 store information such as interval timer values in the general query message, and relay the general query message to each I / F unit.

  In the communication network 1 shown in FIG. 6, the layer 2 switches 10 and 40 are connected in multiple stages, and the layer 2 switches 10 and 40 perform information update and message relay in the same manner as the layer 2 switch 10 of the first embodiment. .

  When there are multicast receiving terminals (terminal devices 20J to 20L) corresponding to the source address specification on the communication network 1, the multicast receiving terminal responds to the Query message with a Report message including the source address and the filter mode. In the present embodiment, a case will be described in which terminal device 20K joins a multicast group as source list A and filter mode INCLUDE.

  The terminal device 20K responds to the Query message from the multicast router 30 with a Report (IS_IN (A)) message (source list A, filter mode INCLUDE) (participation request message). This Report message is received by the I / F unit 11K of the layer 2 switch 40. When receiving the Report message, the I / F unit 11K of the layer 2 switch 40 transfers the Report message to the router mode receiving unit 12K.

  Here, the operation of the router mode receiving units 12J to 12L when receiving the Report message will be described. Since router mode receiving units 12J to 12L perform the same operation, the operation procedure of router mode receiving unit 12K will be described here.

  FIG. 7 is a flowchart showing an operation procedure of the router mode receiving unit when the layer 2 switch according to the second embodiment receives the report message. FIG. 7 shows an operation procedure when the layer 2 switch 40 receives a report message of a group membership management protocol such as IGMPv3 or MLDv2 that can be designated as a source.

  When the router mode receiving unit 12K receives the report message via the I / F unit 11K (step S500), it is included in the report message from the multicast table (multicast table for each I / F unit) in the multicast table storage unit 13K. A multicast address is searched (step S510).

  When there is no entry corresponding to the multicast address of the Report message in the multicast table in the multicast table storage unit 13K (step S510, no entry), the router mode receiving unit 12K determines that the multicast entry (I / F) corresponding to the Report message A multicast entry for each copy) is generated in the multicast table (step S520). Specifically, the filter mode and the source list in the Report message are set in the multicast entry. Here, since the I / F unit 11K receives the Report message for the first time from the terminal device 20K, a multicast entry (source list A, filter mode INCLUDE) corresponding to the I / F unit 11K (terminal device 20K) is generated. .

  After generating the multicast entry, the router mode receiving unit 12K starts the source timer or the filter timer. Here, since the filter mode INCLUDE is generated for the multicast entry, the source timer is started. The source timer here sets the initial value of the source timer to MALI, and subtracts the timer value as time elapses (step S530).

  The router mode reception unit 12K searches for the multicast address included in the Report message from the reception group management table in the reception group management table storage unit 14 (step S540).

  When there is no multicast address entry corresponding to the multicast address in the reception group management table in the reception group management table storage unit 14 (step S540, no entry), the router mode reception unit 12K adds a new entry to the reception group management table. Generate and register. Specifically, a new multicast address, a filter mode and source list in the Report message, a destination I / F (I / F unit 11K), and the like are set in the reception group management table, and the reception group management table storage unit 14 (Step S550).

  Here, since the I / F unit 11K has received the Report message for the first time from the terminal device 20K, the router mode reception unit 12K sets a new entry in the reception group management table.

  The Query reception processing unit 15 generates a Report message based on the newly generated entry. The generated Report message is transmitted to the router connection port via the I / F unit 16 (step S560). The Report message here may be, for example, Report (TO_IN (A)) or Report (ALLOW (A)).

  The Report message transmitted from the router connection port arrives at the I / F unit 11J of the layer 2 switch 10. In the layer 2 switch 10, processing similar to that of the layer 2 switch 40 is executed, and a Report message is transmitted from the I / F unit 16 (router connection port) of the layer 2 switch 10.

  The Report message transmitted from the router connection port of the layer 2 switch 10 arrives at the multicast router 30. The multicast router 30 starts relaying a multicast packet having the multicast address included in the Report message as a destination and having the source address specified in the Report message and the source address requested to be received in the filter mode.

  In the layer 2 switch 10, when the multicast packet from the multicast router 30 is received by the I / F unit 16, the Query reception processing unit 15 refers to the reception group management table and extracts an entry corresponding to the destination multicast address. Among the I / F parts defined in the destination I / F in the entry, the source list of the multicast table for each I / F part, the source address requested for reception in the filter mode, and the source address of the multicast packet The multicast packet is relayed to the matching I / F unit. Here, a multicast entry (source list A, filter mode INCLUDE) corresponding to the I / F unit 11K (terminal device 20K) is generated as a multicast table for each I / F unit. Therefore, the multicast packet is relayed to the I / F unit 11J having the INCLUDE (A) entry.

  The multicast packet sent from the I / F unit 11J of the layer 2 switch 10 is received by the layer 2 switch 40. The layer 2 switch 40 also performs the same processing as the layer 2 switch 10, relays the multicast packet from the I / F unit 11K, and arrives at the terminal device 20K.

  Thus, even in MLDv2 corresponding to source designation, multicast is not relayed to I / F units other than the I / F unit 11K of the layer 2 switch 40, as in MLDv1 and the like not corresponding to source designation. Unnecessary traffic is not relayed to an interface where no multicast receiver exists. As a result, unnecessary traffic relaying can be prevented.

  Next, after the layer 2 switch 10 sets information about the multicast receiver (multicast multicast address entry), the operation when the multicast router 30 receives the general query transmitted at the query interval period by the I / F unit 16 is illustrated. Explanation will be made with reference to FIG.

  FIG. 8 is a flowchart illustrating an operation procedure of the query reception processing unit when the layer 2 switch according to the second embodiment receives the general query message. When the I / F unit 16 of the layer 2 switch 10 receives the general query message (step S600), it transfers the general query message to the query reception processing unit 15.

  The query reception processing unit 15 searches the reception group management table in the reception group management table storage unit 14 and checks whether or not a multicast address entry exists in the reception group management table (step S610).

  Here, since a report message has already been received from the terminal device 20K and an entry has been created in the reception group management table, a multicast multicast address entry exists in the reception group management table. When there is a multicast multicast address entry (step S610, with entry), the Query reception processing unit 15 generates a Report message for each entry using the filter mode and source list of this multicast multicast address entry.

  Then, the generated Report message is transmitted from the router connection port. At this time, information of a plurality of entries may be stored as one address record and transmitted in one Report message. Here, the Query reception processing unit 15 generates a Report (IS_IN (A)) message and transmits it to the router connection port. At this time, the source address of the generated Report message packet is set as an undetermined address (step S620).

  The multicast router 30 is set to process the Report message as a normal message even if the source address of the Report message is an undetermined address. For example, the multicast router 30 is defined by a standard such as RFC3376.

  The multicast router 30 that has received the Report message confirms the presence of the multicast address specified in the multicast address, source list, and filter mode included in the Report message, and continues the multicast relay.

  The query reception processing unit 15 searches the reception group management table to check whether or not the next multicast address entry (another multicast address entry) exists in the reception group management table (step S610). The query reception processing unit 15 performs the process of step S620 on all multicast address entries in the reception group management table.

  When the processing of step S620 is performed on all multicast address entries in the reception group management table, it is determined that there are no remaining multicast address entries in the reception group management table (step S610, no entry). Then, the general query message received by the I / F unit 16 is relayed to all the ports on the terminal devices 20J to 20L via the I / F units 11J to 11L other than the I / F unit 16 (step S630). .

  Note that there is no multicast address entry in the reception group management table until the layer 2 switch 10 receives a report message for the general query message from the terminal device and generates a multicast multicast address entry for the terminal device (step S610, No entry). For this reason, until receiving the Report message from the terminal device, the General Query message is relayed from each I / F unit without creating a Report message in the multicast router 30 (step S630).

  The general query message relayed by the layer 2 switch 10 is received by the layer 2 switch 40, and the layer 2 switch 40 also performs the same processing as the layer 2 switch 10 (relay of queries to each I / F unit).

  If the layer 2 switch 40 relays the general query message to each of the I / F units 11J to 11L, and there is a multicast receiver (terminal device), the multicast receiver reports to the relayed general query message. The message is replied.

  Here, since the terminal device 20K which is a multicast receiver exists ahead of the I / F unit 11K, a Report message is returned from the terminal device 20K to the relayed General Query message. The Report message from the terminal device 20K is received by the I / F unit 11K of the layer 2 switch 40 and transferred to the router mode receiving unit 12K.

  Here, the operation procedure when the router mode receiving unit 12K receives the Report message after setting the multicast address entry in the multicast table will be described with reference to FIG.

  When receiving the Report message via the I / F unit 11K (Step S500), the router mode receiving unit 12K searches the multicast table in the multicast table storage unit 13K for the multicast address included in the Report message (Step S510).

  If there is an entry corresponding to the multicast address in the multicast table in the multicast table storage unit 13K (step S510, entry is present), the router mode reception unit 12K performs a new filter mode and source list update process. Specifically, a new filter mode and source list are extracted based on the filter mode and source list of the entry and the filter mode and source list of the message, and are registered in the multicast table as the new filter mode and source list. . Then, processing corresponding to the combination of the filter mode and the source list (for example, report message transmission processing) is performed. Here, the router mode receiving unit 12K performs, for example, entry update processing and report message transmission from the router connection port based on entry information 101 and 102 described later (step S570).

  Here, the update process of the entry based on the combination of the filter mode and the source list and the content of the Report message transmitted from the router connection port will be described. 9 and 10 are diagrams showing the relationship between the multicast entry state of the router mode receiving unit and the message transmitted from the router connection port. In the entry information 101 and 102 of FIGS. 9 and 10, the management contents of the multicast table entry for each I / F unit to be updated according to the content of the received Report message according to the state of the multicast entry of the router mode receiving units 12J to 12L. The contents of the Report message transmitted from the router connection port are associated with each other.

  In the entry information 101 and 102, a column 91 indicating "Router State", a column 92 indicating "Router Receiver", a column 93 indicating "New Router State", a column 94 indicating "Router Mode Action", and "Host Mode Action" Are associated with each other.

  A column 91 represents the state of the multicast entry for each I / F part before receiving the Report message. The parentheses in the INCLUDE mode represent the source list. In the EXCLUDE mode, the first item in parentheses represents a list of request sources, and the second item represents a list of exclusion sources. A column 92 shows the contents of the Report message received by the I / F units 11J to 11L. The source list is shown in parentheses.

  A column 93 represents a new entry state (entry update contents) due to reception of the Report message. The “+” operator in the source list (in parentheses) indicates a union, the “−” operator indicates a difference set, and the “*” operator indicates a product set.

  A column 94 represents the operation of the router mode receiving units 12J to 12L due to reception of the Report message. “(A) = T (time)” represents that the source timer of the source list A is updated to T. “Delete (A)” indicates that the source list A is deleted. “Filter Timer = T” indicates that the filter timer is updated to T.

  A column 95, which is one of the features of the present invention, indicates information (operation for the multicast router 30) to be transmitted to the router connection port when the Report message is received. “Report (TYPE (A))” indicates that the report type is “TYPE” and the report message of the source list A is transmitted to the router connection port. For example, “Report (BLOCK (A))” indicates that the record type is “BLOCK” and the report message of the source list A is transmitted to the router connection port.

  In this embodiment, IS_IN (A) is received when an entry of INCLUDE (A) is held. As shown in the entry information 102 (009) of FIG. 10, when IS_IN (B) is received when the entry has INCLUDE (A), the new entry state becomes INCLUDE (A + B). ) And IS_IN (A) is received, the new entry state becomes INCLUDE (A + A). That is, the new entry state is INCLUDE (A). Since the operation of the router mode receiving unit 12K is (A) = update to MALI, the source timer of the source list A is updated to MALI.

  Here, since the column 95 indicating “Host Mode Action” is not set, the transmission process of the Report message to the multicast router 30 is not performed.

  After the router mode reception unit 12K performs the filter mode and source list update processing in the multicast table for each I / F unit, the Query reception processing unit 15 updates the multicast address entry in the reception group management table (step S580). ). Specifically, the information of the source list, filter mode, and destination I / F is recalculated based on the update entry contents of the I / F unit 11K and the entry contents of other I / F units.

  In the recalculation of the destination I / F information, for example, the state management method for each interface described in section 4.2 of RFC3810 is used. That is, if there is at least one destination I / F in the EXCLUDE mode, the Query reception processing unit 15 sets the recalculated mode to EXCLUDE. A source list is obtained by excluding the source list of the destination I / F in the INCLUDE mode from the common items of the source lists of the destination I / F in all the EXCLUDE modes. When all destination I / Fs are in INCLUDE mode, the mode after recalculation is INCLUDE mode, and the sum of the source lists of all destination I / Fs is the source list after recalculation.

  Then, when there is a change by comparing the filter mode and source list before and after the update, or by comparing the maximum value of the source timer value of the multicast entry of each destination I / F before and after the update, the LLQT or less before and after the update When the source timer value of the value is updated to MALI, a Report message corresponding to the content of the change is generated and transmitted to the router connection port (step S590).

  Specifically, when the filter mode is changed from the INCLUDE mode to the EXCLUDE mode, a TO_EX type report message is generated, and when the filter mode is changed from the EXCLUDE mode to the INCLUDE mode, a TO_IN type report message is generated.

  When the INCLUDE mode source list is changed, an ALLOW type report message is generated for the added source list, and a BLOCK type report message is generated for the deleted source list.

  When the EXCLUDE mode source list is changed, a BLOCK type report message is generated for the added source list, and an ALLOW type report message is generated for the deleted source list.

  When the maximum source timer value in the reception I / F unit is updated from LLQT or less to a value larger than LLQT, an ALLOW type Report message specifying the source list is generated.

  In order to reduce the number of messages, a report message may be generated by collecting update information of reception group management table entries within the Maximum Response Delay time from receiving the Query. Thereby, a plurality of messages can be aggregated to generate a Report message.

  In consideration of the fact that the layer 2 switches are connected in a plurality of stages, the update information within a time smaller than the maximum response delay may be collected by subtracting the relay delay time between the layer 2 switches.

  Here, the entry timer and source timer values of the reception group management table entry are larger than LLQT, and there is no change in the filter mode or the source list. Therefore, when the reception group management table entry is updated, the Report There is no transmission.

  When the Layer 2 switch 40 transmits a Report (IS_IN (A)) message from the I / F unit 16 that is a router connection port as a process at the time of receiving a general query, the Report (IS_IN (A)) message 2 is received by the switch 10. Similar to the layer 2 switch 40, the layer 2 switch 10 only updates the source timer value of the multicast entry for each I / F unit to MALI, and does not transmit a report message to the multicast router 30. In a state where the receiver is continuously participating in the multicast, the above operation (the operation shown in FIGS. 7 and 8) is periodically executed.

  Next, a case where a recipient is added to the communication network 1 will be described. Here, a case where the terminal device 20L is added as a receiver will be described. FIG. 11 is a diagram for explaining data relay when a recipient is added to the communication network according to the second embodiment.

  Here, a case where data relay between the terminal device 20L and the multicast router 30 is performed in addition to data relay between the terminal device 20K and the multicast router 30 is shown. Specifically, in addition to the data relay of FIG. 6, a Report message 32 from the terminal device 20 </ b> L is relayed by the layer 2 switch 10 and sent to the multicast router 30. A multicast data packet 35 from the multicast router 30 is relayed by the layer 2 switch 10 and sent to the terminal device 20L.

  In order to participate in the multicast, the terminal device 20L transmits, for example, a Report (TO_IN (B)) message as the Report message 32. The I / F unit 11L of the layer 2 switch 10 receives the Report message 32 from the terminal device 20L, and transfers the message to the router mode receiving unit 12L.

  Here, the operation procedure of the router mode receiving unit 12L when receiving the Report message 32 for participating in the multicast will be described with reference to FIG. When the router mode receiving unit 12L of the layer 2 switch 10 receives the Report message via the I / F unit 11L (step S500), the router mode receiving unit 12L uses the multicast table (multicast table for each I / F unit) in the multicast table storage unit 13L. A multicast address included in the Report message is searched (step S510).

  If there is no entry corresponding to the multicast address of the Report message in the multicast table in the multicast table storage unit 13L (step S510, no entry), the router mode receiving unit 12L determines that the multicast entry (I / F) corresponding to the Report message A multicast entry for each copy) is generated in the multicast table (step S520). Specifically, the filter mode and the source list in the Report message are set in the multicast entry. Here, since the I / F unit 11L receives the Report message for the first time from the terminal device 20L, a multicast entry (source list A, filter mode INCLUDE) corresponding to the I / F unit 11L (terminal device 20L) is generated. .

  After generating the multicast entry, the router mode receiving unit 12L starts the source timer (step S530). The source timer here sets the initial value of the source timer to MALI, and subtracts the timer value as time elapses (step S530).

  The router mode reception unit 12L searches for the multicast address included in the Report message from the reception group management table in the reception group management table storage unit 14 (step S540).

  Here, since the multicast address of the terminal device 20K is already registered in the reception group management table, an entry corresponding to the multicast address exists in the reception group management table. If there is an entry corresponding to the multicast address in the reception group management table in the reception group management table storage unit 14 (step S540, there is an entry), the multicast address entry in the reception group management table is updated (step S580). Specifically, the information of the source list, the filter mode, and the destination I / F is recalculated based on the update entry content of the I / F unit 11L and the entry content of the other I / F unit.

  Then, the Query reception processing unit 15 determines whether it is necessary to transmit a Report message, and generates a Report message as necessary. The layer 2 switch 10 here has entries of the target multicast address, filter mode INCLUDE, source list (A), and destination I / F (I / F unit 11J) as multicast address entries in the reception group management table. ing. Accordingly, when a Report (TO_IN (B)) message is received from the I / F unit 11L, the Query reception processing unit 15 updates the source list of the multicast address entry to (A + B) based on the entry information 101, and the destination I / F The I / F unit 11L is added to the information of F.

  The source timer in the range of the source list (A) is larger than LLQT, but the range of the source list (BA) is a newly added source list. A Type Report message is generated and transmitted to the router connection port (step S590).

  This Report message arrives at the multicast router 30. The multicast router 30 adds the source list (B-A) to the source list, and starts relaying multicast in the range of the source list (B-A).

  Next, processing when the recipient explicitly sends a BLOCK type Report message to change a part of the source list will be described. For example, the terminal device 20K transmits a Report message specifying BLOCK (C) in order to exclude the source list C from the multicast source list A participating in the INCLUDE mode.

  Upon receiving the Report message from the terminal device 20K, the I / F unit 11K of the layer 2 switch 40 transfers the report message to the router mode receiving unit 12K. The router mode receiving unit 12K performs processing based on the entry information 101 and 102 for the corresponding entry in the multicast table of the I / F unit 11K. Here, in order to receive BLOCK (C) in the INCLUDE (A) state, the source timer of the source list (A * C) is shortened to LLQT, and Report (BLOCK (C)) is transmitted from the router connection port (FIG. 9 002). The Report message here is transmitted to the upstream side for the entire source list C in the BLOCK message.

  For the corresponding entry in the reception group management table, the Query reception processing unit 15 extracts the source list of the entries of the same multicast group address that other I / F units have. In this source list, a source whose source timer value is larger than LLQT is excluded from the source list C, and the source timer value is updated to LLQT for the source list C from which a source larger than LLQT is excluded. Here, since the other I / F unit does not have a multicast entry, the source timer value is updated to LLQT for the entire source list C.

  The Report (BLOCK (C)) message transmitted from the router connection port arrives at the layer 2 switch 10 and is transferred to the router mode receiving unit 12J. Upon receiving this message, the router mode receiving unit 12J performs processing according to the entry information 101 and 102.

  Here, in order to receive BLOCK (C) in the INCLUDE (A) state, the router mode receiving unit 12J shortens the source timer of the source list (A * C) to LLQT, and reports from the router connection port to Report (BLOCK (CLOCK )) Send a message (the entire source list included in the received BLOCK message). Further, the Query reception processing unit 15 updates the corresponding entry in the reception group management table.

  The layer 2 switch 10 here has entries of the target multicast address, filter mode INCLUDE, and source list (A + B) as reception group management table entries. Even when a Report (BLOCK (C)) message is received from the I / F unit 11J, the source list of the I / F unit 11L does not change. For this reason, Report transmission triggered by a change in the contents of the reception group management table entry is not performed.

  The Report message transmitted from the router connection port of the layer 2 switch 10 arrives at the multicast router 30. The multicast router 30 updates the source timer to LLQT with respect to the source list of the multicast group address indicated in the Report message, and transmits a Multicast Address and Source Specific Query message. When the I / F unit 16 of the layer 2 switch 10 receives the Specific Query message from the multicast router 30, the I / F unit 16 transmits the message to the Query reception processing unit 15.

  Here, a process when the Query reception processing unit 15 receives a Specific Query message will be described. FIG. 12 is a flowchart illustrating an operation procedure of the query reception processing unit when the layer 2 switch according to the second embodiment receives the specific query message.

  FIG. 12 shows an operation procedure when the layer 2 switch 10 receives a specific query message including source designation of a group membership management protocol such as IGMPv3 or MLDv2 that can be designated as a source.

  When receiving the Specific Query message (step S700), the I / F unit 16 of the layer 2 switch 10 transfers the Specific Query message to the Query reception processing unit 15.

  The query reception processing unit 15 searches the reception group management table in the reception group management table storage unit 14. The Query reception processing unit 15 checks whether or not there is a multicast address entry corresponding to the multicast group address indicated by the Specific Query message in the reception group management table (Step S710).

  When there is a multicast address entry of the multicast group address indicated by the Specific Query message in the reception group management table (step S710, there is an entry), the Query reception processing unit 15 performs I / F for each destination I / F of the multicast address entry. Check the multicast address entry for each part F. Then, a source that is included in the source list specified by the Specific Query message and has a source address whose source timer value is larger than LLQT is extracted (step S720). Then, the extracted sources are collected in a source list, and one IS_IN type Report message is generated and transmitted from the router connection port (step S730).

  The entry of the I / F unit 11J is a source timer (A * C) indicating a value equal to or less than INCLUDE (A), LLQT, and the entry of the I / F unit 11L indicates a value larger than INCLUDE (B), LLQT. Source timer (B). Accordingly, the Query reception processing unit 15 here needs the source list (B * C), and therefore generates a Report (IS_IN (B * C)) message and transmits it from the router connection port.

  Further, the Query reception processing unit 15 extracts an I / F unit having a source list member equal to or less than the source timer value LLQT from each destination I / F. Then, the Specific Query message is relayed to each extracted I / F unit (step S740).

  The Query reception processing unit 15 here relays the Query message to the I / F unit 11J because the source timer (A * C) of the I / F unit 11J is equal to or less than LLQT. Since the source timer (B) of the I / F unit 11L is larger than LLQT, the Query message is not relayed to the I / F unit 11L.

  The Specific Query message relayed by the Query reception processing unit 15 arrives at the layer 2 switch 40. The layer 2 switch 40 performs the same processing as the layer 2 switch 10. Here, the Specific Query message is relayed to the I / F unit 11K whose source timer (A * C) is LLQT or less. In addition, since the source timer value is all equal to or less than LLQT in the range of the source list (C) specified by the specific query, the layer 2 switch 40 does not transmit a report message to the router connection port.

  In this way, the I / F unit (I / F unit 11J of the layer 2 switch 40) that does not have an entry for the designated multicast address, or the I / F unit (layer 2 switch in which all source timer values are larger than LLQT). Therefore, the specific query message is not relayed to the 10 I / F unit 11L).

  Also, if there is no receiver ahead of the I / F unit 11K that relayed the specific query message, the report message is not responded to the specific query message. In this case, since the source timer of the multicast table entry for each I / F part expires, the source list (A * C) is deleted. Then, the reception group management table entry is updated, and the source list is updated to (AC). As a result, the layer 2 switch 40 stops relaying multicast packets from source addresses other than the source list (AC).

  In the layer 2 switch 10 as well, the source timer times out due to the non-reception of the Report message, and from the entry of the multicast table for each I / F unit (the multicast table of the I / F unit 11J), Delete the source. Then, the reception group management table entry is updated, and the source list is updated to (B + (AC)). As a result, the layer 2 switch 10 stops relaying the multicast packet from the source address corresponding to the source list (A * C).

  The multicast router 30 receives only IS_IN (B * C) as a response to the Specific Query for the source list (C). For this reason, the source timer for the source list (C-B) times out and is deleted from the source list. Thereby, the relay of the multicast packet from the source address corresponding to the source list (CB) is stopped.

  In this way, when a receiver in INCLUDE mode transmits a BLOCK type Report message that deletes an arbitrary source from the source list, multicast relay to the I / F unit that accommodates the receiver stops, Multicast relay to other I / F units will continue.

  In addition, when transmitting a BLOCK type Report message to the upstream side (multicast router 30 side), the BLOCK message is transmitted to the upstream side for the entire source list in the BLOCK message, so that layer 2 switches are connected in multiple stages. Even if it is, the specific query message for the appropriate source list range is transmitted from the multicast router 30.

  In addition, when a receiver exists ahead of the I / F unit 11K of the layer 2 switch 40 and an IS_IN (C) type Report message is responded to the Specific Query message, this message is sent to the I / F unit 11K. Received at. This message is transferred to the router mode receiving unit 12K.

  Here, the operation procedure when the router mode receiving unit 12K receives an IS_IN (C) type report message after relaying the specific query message to the I / F unit 11K whose source timer (A * C) is LLQT or less. Will be described with reference to FIG.

  When the router mode receiving unit 12K receives an IS_IN (C) type report message via the I / F unit 11K (step S500), the router mode receiving unit 12K searches for the multicast address included in the report message from the multicast table in the multicast table storage unit 13K. (Step S510).

  When there is an entry corresponding to the multicast address in the multicast table in the multicast table storage unit 13K (step S510, there is an entry), the router mode receiving unit 12K adds the new filter mode and source list according to the entry information 101 and 102. Update processing and report message transmission processing are performed (step S570).

  Next, the Query reception processing unit 15 updates the multicast address entry in the reception group management table (step S580). Specifically, the information of the source list, filter mode, and destination I / F is recalculated based on the update entry contents of the I / F unit 11K and the entry contents of other I / F units.

  At this time, the Query reception processing unit 15 confirms the multicast address entry in the multicast table for each I / F unit with respect to each destination I / F of the multicast address entry in the reception group management table. From the source timer value equal to or lower than LLQT in the process of step S570, a source that is the same source as the source updated to a value larger than the source timer value and whose source timer value of the multicast address entry is larger than LLQT is extracted. . Then, a Report message is generated for the source list in which the extracted source is deleted from the source list, and transmitted to each router connection port (step S590). Here, the Query reception processing unit 15 generates and transmits a Report (ALLOW (C)) message.

  This Report (ALLOW (C)) message is received by the layer 2 switch 10, and the layer 2 switch 10 performs the same processing as the layer 2 switch 40. As a result, a Report (IS_IN (C-B)) message is transmitted to the router connection port. When receiving the Report message from the layer 2 switch 10, the multicast router 30 updates the source timer to MALI and continues the multicast relay.

  In this embodiment, a case has been described in which a BLOCK type report message is transmitted to the router connection port when a BLOCK type report message is received from the receiver and the source timer value is set to LLQT. However, a BLOCK type Report message to the router connection port may be transmitted when the source timer is updated to a value equal to or less than LLQT due to aging. Also in this case, the layer 2 switches 10 and 40 perform the same operation as the layer 2 switches 10 and 40 described above.

  As described above, according to the second embodiment, whether or not a Report message needs to be transmitted is determined based on whether or not a change across the threshold (LLQT) has been performed when the source timer value is updated. Even if there are other recipients in the segment, the recipient can be surely confirmed by exchanging few messages. Therefore, multicast relay can be continued efficiently.

  In addition, when transmitting a BLOCK type Report message to the upstream side, the BLOCK message is transmitted to the upstream side for the entire source list in the BLOCK message, so that the layer 2 switch is connected in multiple stages. Also, a specific query message for an appropriate source list range is transmitted from the multicast router 30. Therefore, the presence / absence of the terminal device can be confirmed with respect to the source list in the range that does not leak on the downstream side, and the group member can be quickly deleted.

Embodiment 3 FIG.
Next, a third embodiment of the present invention will be described with reference to FIGS. 7 and 12 to 13. In the third embodiment, when the recipient is in the EXCLUDE mode (exclusion request mode), a transition from the EXCLUDE mode to the INCLUDE mode (reception request mode) is performed using a Null message.

  FIG. 13 is a diagram for explaining data relay in the communication network according to the third embodiment. Of the constituent elements in FIG. 13, constituent elements that achieve the same functions as those of the communication network 1 of the first embodiment shown in FIG. 1 are given the same numbers, and redundant descriptions are omitted.

  Here, a case is shown in which the layer 2 switch 10 relays the Query message 51 from the multicast router 30 to the terminal devices 20J to 20L and relays the Report message 62 from the terminal device 20J to the multicast router 30. Here, a case is shown in which the layer 2 switch 10 relays the multicast data packet 63 from the multicast router 30 to the terminal device 20J.

  In the following description, it is assumed that there is a terminal device 20J in which the communication network 1 supports IGMPv3 or MLDv2 as a multicast receiver and can specify a source address.

  Next, an operation procedure of the layer 2 switch according to the third embodiment will be described. As with the layer 2 switches 10 and 40 of the first and second embodiments, the multicast router 30 periodically transmits a general query message, the layer 2 switch 10 stores interval timer value information and the like in the message, and receives the received message. Are relayed to each I / F unit.

  In the present embodiment, a case will be described in which terminal device 20J joins a multicast group as exclusion list A and filter mode EXCLUDE in communication network 1.

  The terminal device 20J responds with a Report (IS_EX (A)) message in response to the General Query message from the multicast router 30. This Report message is received by the I / F unit 11J of the layer 2 switch 10, and the I / F unit 11J transfers the received Report message to the router mode receiving unit 12J.

  Here, the operation procedure of the router mode reception unit when receiving the Report message will be described with reference to FIG. When the router mode receiving unit 12J receives the Report message via the I / F unit 11J (step S500), it is included in the Report message from the multicast table in the multicast table storage unit 13J (the multicast table of the I / F unit 11J). A multicast address is searched (step S510).

  When there is no entry corresponding to the multicast address of the Report message in the multicast table in the multicast table storage unit 13J (step S510, no entry), the router mode receiving unit 12J reads the multicast entry (I / F) corresponding to the Report message. A multicast entry for each copy) is generated in the multicast table (step S520). Specifically, the filter mode and the source list in the Report message are set in the multicast entry. Here, since the I / F unit 11J receives the Report message for the first time from the terminal device 20J, a multicast entry (source list A, filter mode EXCLUDE) corresponding to the I / F unit 11J (terminal device 20J) is generated. .

  After generating the multicast entry, the router mode receiving unit 12J starts the source timer or the filter timer. Here, since the filter mode EXCLUDE is generated for the multicast entry, the filter timer is started. The filter timer here sets the filter timer initial value to MALI, and subtracts the timer value as time passes (step S530).

  The router mode reception unit 12J searches for the multicast address included in the Report message from the reception group management table in the reception group management table storage unit 14 (step S540).

  When there is no entry corresponding to the multicast address in the reception group management table in the reception group management table storage unit 14 (step S540, no entry), the router mode reception unit 12J generates a new entry in the reception group management table. And register. Specifically, a new multicast address, a filter mode and source list in the Report message, a destination I / F (I / F unit 11J), and the like are set in the reception group management table, and the reception group management table storage unit 14 (Step S550).

  Here, since the I / F unit 11J receives a Report message for the first time from the terminal device 20J, the router mode receiving unit 12J sets a new entry in the reception group management table. The additional entry to the reception group management table here is, for example, EXCLUDE (Null, A).

  The Query reception processing unit 15 generates a Report message based on the newly generated entry. The generated Report message is transmitted to the router connection port via the I / F unit 16 (step 560). The Report message here is, for example, Report (TO_EX (A)).

  The Report message transmitted from the router connection port arrives at the multicast router 30. The multicast router 30 starts relaying a multicast packet having the multicast address included in the Report message as a destination and having the source address specified in the Report message and the source address requested to be received in the filter mode. At this time, the record managed by the multicast router 30 is EXCLUDE (Null, A).

  In the layer 2 switch 10, when the multicast packet from the multicast router 30 is received by the I / F unit 16, the Query reception processing unit 15 refers to the reception group management table and extracts an entry corresponding to the destination multicast address. Among the I / F parts defined in the destination I / F in the entry, the source list of the multicast table for each I / F part, the source address requested for reception in the filter mode, and the source address of the multicast packet The multicast packet is relayed to the matching I / F unit. Here, a multicast entry (source list A, filter mode EXCLUDE) corresponding to the I / F unit 11J (terminal device 20J) is generated as a multicast table for each I / F unit. Therefore, the multicast packet is relayed to the I / F unit 11J having the EXCLUDE (A) entry.

  As described above, even if there is an EXCLUDE mode receiver in IGMPv3 or MLDv2 corresponding to the source designation, multicast is not relayed to the I / F unit other than the I / F unit 11J. Unnecessary traffic is not relayed to the interface that does not. As a result, unnecessary traffic relaying can be prevented.

  Next, the operation when the I / F unit 16 receives the general query transmitted by the multicast router 30 at the query interval period after the layer 2 switch 10 sets information regarding the multicast receiver will be described.

  When the I / F unit 16 receives the general query message, the message is transferred to the query reception processing unit 15. The processing of the Query reception processing unit 15 generates and transmits a Report message and relays the General Query message according to the same procedure as the operation procedure shown in FIG.

  In the present embodiment, in the process of step S620, the Query reception processing unit 15 generates a Report (IS_EX (A)) message and transmits it to the multicast router 30. At this time, the source address of the generated Report message packet is set as an undetermined address.

  The multicast router 30 that has received the Report message sent by the layer 2 switch 10 to the router connection port confirms the multicast address specified in the multicast address, the source list, and the filter mode included in the Report message. Continue relaying.

  If the layer 2 switch 10 relays the general query message to each of the I / F units 11J to 11L, and there is a multicast receiver, a report message is returned from the multicast receiver to the relayed general query message. The

  Here, since the terminal device 20J that is a multicast receiver exists ahead of the I / F unit 11J, a Report message is returned from the terminal device 20J to the relayed General Query message. The Report message from the terminal device 20J is received by the I / F unit 11J of the layer 2 switch 10 and transferred to the router mode receiving unit 12J.

  Here, an operation procedure when the router mode receiving unit 12J receives the Report message after setting the multicast address entry in the multicast table will be described with reference to FIG.

  When the router mode receiving unit 12J receives the Report message via the I / F unit 11J (step S500), the router mode receiving unit 12J searches for the multicast address included in the report message from the multicast table in the multicast table storage unit 13J (step S510).

  If there is an entry corresponding to the multicast address in the multicast table in the multicast table storage unit 13J (step S510, there is an entry), the router mode receiving unit 12J performs a new filter mode and source list update process. Specifically, a new filter mode and source list are extracted based on the filter mode and source list of the entry and the filter mode and source list of the message, and are registered in the multicast table as the new filter mode and source list. . Then, processing corresponding to the combination of the filter mode and the source list (for example, report message transmission processing) is performed. The router mode receiving unit 12J here performs entry update processing and message transmission from the router connection port based on the entry information 101 and 102, for example (step S570). In the present embodiment, since IS_EX (A) is received when EXCLUDE (A) has an entry, the filter timer is only updated to MALI.

  After the router mode reception unit 12J performs the filter mode and source list update processing in the multicast table for each I / F unit, the Query reception processing unit 15 updates the multicast address entry in the reception group management table (step S580). ). Specifically, the information of the source list, filter mode, and destination I / F is recalculated based on the update entry contents of the I / F unit 11J and the entry contents of other I / F units.

  Then, the Query reception processing unit 15 determines whether it is necessary to transmit a Report message, and generates a Report message as necessary. Whether the Report message needs to be transmitted is determined by the same process as in step S590 described above.

  Here, there is no change in the entry contents, and there is no change in the filter mode or the source list. Therefore, the Report message is not transmitted in the process of step S590. In a state where the receiver is continuously participating in the multicast, the above operation (the operation shown in FIGS. 7 and 8) is periodically executed.

  Next, a case where a receiver in INCLUDE mode is added to the communication network 1 will be described. Here, a case where the terminal device 20L is added as a receiver will be described. In FIG. 13, it is assumed that the terminal device 20L also transmits a Report (TO_IN (B)) message, for example, in order to participate in the multicast.

  Here, the operation procedure of the router mode receiving unit 12L when receiving a Report message for participating in multicast will be described with reference to FIG. The I / F unit 11L of the layer 2 switch 10 receives the Report message and relays the received message to the router mode receiving unit 12L.

  When the router mode receiving unit 12L of the layer 2 switch 10 receives the Report message via the I / F unit 11L (step S500), the multicast mode in the multicast table storage unit 13L (the multicast table of the I / F unit 11L) A multicast address included in the Report message is searched (step S510).

  If there is no entry corresponding to the multicast address of the Report message in the multicast table in the multicast table storage unit 13L (step S510, no entry), the router mode receiving unit 12L determines that the multicast entry (I / F) corresponding to the Report message A multicast entry for each copy) is generated in the multicast table (step S520). Specifically, the filter mode and the source list in the Report message are set in the multicast entry. Here, since the I / F unit 11L receives the Report message for the first time from the terminal device 20L, a multicast entry (source list A, filter mode INCLUDE) corresponding to the I / F unit 11L (terminal device 20L) is generated. .

  After generating the multicast entry, the router mode receiving unit 12L starts the source timer (step S530). The source timer here sets the initial value of the source timer to MALI, and subtracts the timer value as time elapses (step S530).

  The router mode reception unit 12L searches for the multicast address included in the Report message from the reception group management table in the reception group management table storage unit 14 (step S540).

  Here, since the multicast address of the terminal device 20J is already registered in the reception group management table, an entry corresponding to the multicast address exists in the reception group management table. If there is an entry corresponding to the multicast address in the reception group management table in the reception group management table storage unit 14 (step S540, there is an entry), the multicast address entry in the reception group management table is updated (step S580). Specifically, the information of the source list, the filter mode, and the destination I / F is recalculated based on the update entry content of the I / F unit 11L and the entry content of the other I / F unit.

  Then, the Query reception processing unit 15 determines whether it is necessary to transmit a Report message, and generates a Report message as necessary. Whether the Report message needs to be transmitted is determined by the same process as in step S590 described above.

  The layer 2 switch 10 here has entries of the target multicast address, filter mode EXCLUDE, source list Null, and exclusion list A as reception group management table entries. Therefore, when a Report (TO_IN (B)) message is received from the I / F unit 11L, an INCLUDE (B) entry is generated in the multicast table of the I / F unit 11L, and the source list of the reception group management entry is set to (B). Update the exclusion list to (A-B) and add the I / F unit 11L to the destination I / F information.

  Further, since the range of the source list (A * B) is a newly added source list, the Query reception processing unit 15 generates an ALLOW type Report message for the source list (A * B), and transmits the router connection port. (Step S590).

  This Report message arrives at the multicast router 30. The multicast router 30 adds the source list (A * B) to the source list, updates the multicast management record to EXCLUDE (B, AB), and starts relaying multicast within the range of the multicast management record (source list). To do.

  Next, processing when the recipient explicitly sends a BLOCK type Report message to change a part of the source list will be described. For example, the terminal device 20J transmits a Report message specifying BLOCK (C) in order to exclude the source list C from the multicast source list participating in the EXCLUDE mode. Here, the source list C is a source list that does not overlap with the exclusion list A.

  Upon receiving the Report message from the terminal device 20J, the I / F unit 11J of the layer 2 switch 40 transfers the report message to the router mode receiving unit 12J. The router mode receiving unit 12J performs processing based on the entry information 101 and 102 for the corresponding entry in the multicast table of the I / F unit 11J. Here, in order to receive BLOCK (C) in the EXCLUDE (Null, A) state, the source timer of the source list (C) is started as LLQT, and Report (BLOCK (C)) is transmitted from the router connection port.

  The Report message transmitted from the router connection port of the layer 2 switch 10 arrives at the multicast router 30. The multicast router 30 updates the source timer to LLQT for the multicast group address source list (C) indicated in the Report message, and transmits a Multicast Address and Source Specific Query message. When the I / F unit 16 of the layer 2 switch 10 receives the Specific Query message from the multicast router 30, the I / F unit 16 transmits the message to the Query reception processing unit 15.

  Here, a process when the Query reception processing unit 15 receives the Specific Query message will be described with reference to FIG. Note that the processing in steps S700 to S720 here is the same as the processing in the second embodiment, and a description thereof will be omitted.

  In this embodiment, the entry of the I / F unit 11J is EXCLUDE (A) and the source timer (C) <LLQT, and the entry of the I / F unit 11L is INCLUDE (B) and the source timer (B)> LLQT. is there. Therefore, the Query reception processing unit 15 generates a Report (IS_IN (B * C)) message and transmits it from the router connection port (step S730).

  Further, since the source timer (C) of the I / F unit 11J is equal to or lower than LLQT, the Query reception processing unit 15 relays the Specific Query message to the I / F unit 11J. Further, the Query reception processing unit 15 does not relay the Query message because the source timer (B) of the I / F unit 11L is larger than the LLQT (Step S740).

  In this way, the Specific Query message is not relayed to an I / F unit that does not have an entry for the designated multicast address or an I / F unit in which all the source timer values are larger than LLQT, and control messages are exchanged. It can be reduced.

  Further, if there is no receiver requesting the target source at the end of the I / F unit 11J that relayed the specific query message, the report message is not responded to the specific query message. In this case, since the source timer included in the multicast table entry for each I / F part expires, the source list (C) is deleted and added to the exclusion list. The entry of the I / F unit 11J is EXCLUDE (Null, A + C). Further, the Query reception processing unit 15 updates the reception group management table entry, and updates the source list to (B−C) and the exclusion list to (A + C−B). As a result, the layer 2 switch 10 stops relaying the multicast packet from the newly excluded source (C-A-B).

  The multicast router 30 receives only the Report (IS_IN (B * C)) message as a response to the Specific Query for the source list (C). For this reason, the source timer times out for the source list (CB) and is deleted from the source list. As a result, the multicast router 30 stops relaying the multicast packet from the source address corresponding to the source list (C-B).

  Thus, when a receiver in EXCLUDE mode transmits a BLOCK type Report message that adds an arbitrary source to the exclusion list, multicast relay to the I / F unit that accommodates the receiver stops, Multicast relay to other I / F units will continue.

  Also, when transmitting a BLOCK type report message to the upstream side, the BLOCK message is transmitted to the upstream side for the entire source list in the BLOCK message, so even if the layer 2 switch is connected in multiple stages A specific query message for an appropriate source list range is transmitted from the multicast router 30. As a result, it is possible to confirm the presence or absence of a receiver in the source list in a range that does not leak on the downstream side, and it is possible to quickly delete a group member.

  Note that if the recipient exists ahead of the I / F unit 11J of the layer 2 switch 10 and an IS_IN (C) type Report message is responded to the Specific Query message, this message is sent to the I / F unit 11J. Received at. This message is transferred to the router mode receiving unit 12J.

  Here, the operation procedure when the router mode receiving unit 12J receives the Report message after relaying the Specific Query message to the I / F unit 11J whose source timer (C) is LLQT or less will be described with reference to FIG. To do.

  When receiving the Report message via the I / F unit 11K (Step S500), the router mode receiving unit 12K searches the multicast table in the multicast table storage unit 13K for the multicast address included in the Report message (Step S510).

  When there is an entry corresponding to the multicast address in the multicast table in the multicast table storage unit 13K (step S510, there is an entry), the router mode receiving unit 12K adds the new filter mode and source list according to the entry information 101 and 102. Update processing and report message transmission processing are performed (step S570).

  Next, the Query reception processing unit 15 updates the multicast address entry in the reception group management table (step S580). Specifically, the information of the source list, filter mode, and destination I / F is recalculated based on the update entry contents of the I / F unit 11J and the entry contents of other I / F units.

  At this time, the Query reception processing unit 15 confirms the multicast entry in the multicast table for each I / F unit with respect to each destination I / F of the multicast address entry in the reception group management table. In step S570, a source that is the same source as the source timer value updated from the source timer value equal to or lower than LLQT to a larger value and whose source timer value of the multicast address entry is larger than LLQT is extracted. Then, a Report message is generated for the source list in which the extracted source is deleted from the source list, and transmitted to each router connection port. Here, since the source timer (B) of the I / F unit 11L has a value larger than LLQT, a Report (IS_IN (CB)) message is generated and transmitted. When receiving the Report message from the layer 2 switch 10, the multicast router 30 updates the source timer to MALI and continues the multicast relay.

  In this way, since it is determined whether or not the Report message needs to be transmitted depending on whether or not a change across the threshold (LLQT) has been performed when the source timer value is updated, other receivers may be included in the segment that transmitted the BLOCK message. Even if it exists, it is possible to confirm the recipient reliably by exchanging few messages. Therefore, multicast relay can be continued efficiently.

  Next, an operation when the receiver changes from the EXCLUDE mode to the INCLUDE mode will be described. In this case, when the terminal device 20J transmits a Report message specifying TO_IN (C) to change from the multicast participating in the EXCLUDE mode to the INCLUDE mode specifying the source list C (to change the source list). Will be described.

  When the I / F unit 11J of the layer 2 switch 10 receives the Report message specifying TO_IN (C), the I / F unit 11J performs processing based on the entry information 101 and 102 for the corresponding entry in the multicast table for each I / F unit. .

  In the present embodiment, TO_IN (C) is received in the EXCLUDE (Null, A) state (“008” in FIG. 9), so that the I / F unit 11J transitions to the EXCLUDE (C, A-C) state. To do. Also, the source timer of the source list (C) is started as MALI, and the filter timer is updated to LLQT. Further, Report (TO_IN ({})) is transmitted from the I / F unit 16 which is a router connection port. Since the request list is Null in the EXCLUDE mode entry of the I / F unit 11J, the content of the BLOCK type Report message is empty. For this reason, the Report message is not transmitted.

  The Report message transmitted from the router connection port arrives at the multicast router 30. The multicast router 30 updates the record in the EXCLUDE mode, updates the source timer of the request list (B + C) to LLQT, and transmits a Multicast Address and Source Specific Query message (first query message). Further, the multicast router 30 updates the filter timer to LLQT and transmits a Multicast Address Specific Query message (second Query message).

  Here, a process when the Query reception processing unit 15 receives the Specific Query message will be described with reference to FIG. Note that the processing in steps S700 to S720 here is the same as the processing in the second embodiment, and a description thereof will be omitted.

  In this embodiment, the entry of the I / F unit 11J is EXCLUDE (AC) and the source timer (C)> LLQT, and the entry of the I / F unit 11L is INCLUDE (B) and the source timer (B)> LLQT. Therefore, the Query reception processing unit 15 generates a Report (IS_IN (B + C)) message and transmits it from the router connection port (step S730).

  Further, the Query reception processing unit 15 does not relay the first Query message because the I / F unit 11J does not have a source timer equal to or less than LLQT (step S740). The I / F unit 16 receives the second Query message following the first Query message, and transfers it to the Query reception processing unit 15.

  Here, an operation when the Query reception processing unit 15 receives the Multicast Address Specific Query message will be described. FIG. 14 is a flowchart illustrating an operation procedure when the Query receiving unit receives a Multicast Address Specific Query message.

  FIG. 14 illustrates an operation when the layer 2 switch 10 receives a specific query message that does not accompany the source designation of a group membership management protocol such as IGMPv3 or MLDv2 that can be designated.

  When receiving the Multicast Address Specific Query message (second Query message) via the I / F unit 16 (Step S800), the Query reception processing unit 15 receives the multicast group address indicated by the Specific Query message in the reception group management table. It is confirmed whether there is a multicast address entry corresponding to (step S810).

  If there is an entry for the instructed multicast address (step S810, entry exists), the Query reception processing unit 15 checks the multicast entry for each I / F unit for each destination I / F of the entry. Then, the entries of the respective I / F units excluding the I / F unit whose filter timer value is equal to or less than LLQT are aggregated to generate one Report message, which is transmitted from the router connection port (step S820).

  In the present embodiment, the entry of the I / F unit 11J is EXCLUDE (AC), filter timer <LLQT, and the entry of the I / F unit 11L is INCLUDE (B). Therefore, the Query reception processing unit 15 generates a Report (IS_IN (B)) message and transmits it from the router connection port.

  Also, the Query reception processing unit 15 has each I / F unit having a source list member whose source timer value is LLQT or less, or the filter timer value is LLQT or less among the I / F units that are the destination I / F. The second Query message is relayed to each I / F unit (member) having the EXCLUDE mode entry (step S830).

  Here, the entry of the I / F unit 11J is EXCLUDE (AC) and filter timer <LLQT, and the entry of the I / F unit 11L is INCLUDE (B) and source timer (B)> LLQT. Accordingly, the Query reception processing unit 15 relays the second Query message only to the I / F unit 11J.

  In this way, the Specific Query message is not relayed to an I / F unit that does not have an entry for a designated multicast address, or an I / F unit that has a source timer value larger than LLQT. Can be reduced.

  As a result, the I / F unit 11J of the layer 2 switch 10 transmits the second Query message, and the terminal device 20J responds to the Report (IS_IN (C)) message with respect to the second Query message.

  Since each Report message transmitted by the layer 2 switch 10 is transmitted as a response to the Query message, a transmission waiting delay time smaller than LLQT is prepared, and a Report transmission request generated within that time is provided as one Report. You may aggregate and transmit to a message.

  When receiving the Report (IS_IN (C)) message from the terminal device 20J, the I / F unit 11J performs processing based on the entry information 101 and 102 for the corresponding entry in the multicast table for each I / F unit. .

  Here, in order to receive IS_IN (C) in the EXCLUDE (C, A-C) state, the source timer of the source list (C) is only updated to MALI (010 in FIG. 10). Thereafter, since the filter timer expires, the entry of the I / F unit 11J transitions to INCLUDE (C). The reception group management table entry is updated to INCLUDE (B + C).

  Thus, the multicast router 30 only receives a Report (IS_IN (B + C)) message in response to the transmission of the Query message. As a result, in the multicast router 30, the filter timer expires, and the management record transitions to INCLUDE (B + C).

  As described above, according to the third embodiment, when the filter timer is updated to LLQT or less, it is prompted to transmit a Multicast Address Specific Query message from the multicast router 30 by transmitting a Null TO_IN type Report message. It is possible to quickly confirm the presence of the receiver by relaying the Query message. As a result, the transition from the EXCLUDE mode to the INCLUDE mode can be performed reliably and quickly.

  Further, since the presence of the receiver is confirmed using the Query message transmitted from the multicast router 30, the Query message packet is not discarded by the receiver. Furthermore, since the IP address used by the layer 2 switch 10 can be assigned without associating it with the Queryer selection process, the multicast router 30 can easily manage the address.

  Since the response message contents corresponding to the values of the source timer and the filter timer are generated when the Specific Query message is received and the I / F part of the relay destination is selected, the message exchange is performed with a few message exchange procedures. It becomes possible.

Embodiment 4 FIG.
Next, a fourth embodiment of the present invention will be described with reference to FIGS. In the fourth embodiment, when a change in the network topology is detected, a TO_IN type Report message with an empty transmission source list (reception request target) is transmitted to the router connection port to quickly reconfigure the multicast relay tree. .

  FIG. 15 is a diagram showing a configuration of a communication network having a layer 2 switch according to Embodiment 4 of the present invention. Components in FIG. 15 that achieve the same functions as the communication networks 1 and 2 in the first and second embodiments shown in FIG. 1 and FIG. To do.

  The communication network 3 includes a multicast router 30, a layer 2 switch 10, layer 2 switches 41 and 42, and terminal devices 20P to 20S. The multicast router 30 is connected to the layer 2 switch 10, and the layer 2 switch 10 is connected to the layer 2 switches 41 and 42. The layer 2 switch 41 is connected to the terminal device 20P and the terminal device 20Q, and the layer 2 switch 42 is connected to the terminal device 20R and the terminal device 20S.

  The layer 2 switches 41 and 42 are the same switches as the layer 2 switch 40 (layer 2 switch 10). The terminal devices 20P to 20S are terminal devices similar to the terminal devices 20J to 20L.

  The layer 2 switch 41 and the layer 2 switch 42 are connected to form a loop path, but the path between the layer 2 switch 41 and the layer 2 switch 42 is blocked when no link failure occurs. . As a result, the relay of packets between the layer 2 switches 42 and 43 is blocked when no link failure has occurred.

  In the communication network 3, the layer 2 switch 41 relays the report message 54 from the terminal device 20P to the layer 2 switch 10, and the layer 2 switch 42 relays the report message 54 from the terminal devices 20R and 20S to the layer 2 switch 10. ing. The layer 2 switch 10 relays the report message 54 to the multicast router 30.

  Further, the layer 2 switch 10 relays the query message 51 from the multicast router 30 to the layer 2 switches 41 and 42. Then, the layer 2 switch 41 relays the query message 51 from the layer 2 switch 10 to the terminal devices 20P and 20Q, and the layer 2 switch 42 relays the query message 51 from the layer 2 switch 10 to the terminal devices 20R and 20S. Yes.

  Next, an operation procedure of the layer 2 switch according to the fourth embodiment will be described. In the communication network 3, since the layer 2 switches 10, 41, and 42 constitute a physical loop, they operate a configuration control mechanism that forms a logical tree topology and prevents infinite circulation of packets. And For example, in the layer 2 switches 10, 41, 42, the configuration control mechanism is operated by IEEE 802.1D Spanning Tree Protocol or the like.

  Of the terminal devices, the terminal devices 20P, 20R, and 20S are assumed to participate in the multicast group by a multicast group membership management protocol such as IGMP and MLD and receive multicast data packets from the multicast router 30. Each of the layer 2 switches 10, 41, and 42 performs a snooping operation, and has a multicast table and a reception group management table for each I / F unit.

  When a failure occurs in the link between the layer 2 switch 41 and the layer 2 switch 42, the link between the layer 2 switch 41 and the layer 2 switch 42 is released from blocking by the configuration control mechanism.

  Here, data relay when a failure occurs in the link between the layer 2 switch 41 and the layer 2 switch 42 will be described. FIG. 16 is a diagram for explaining data relaying when a link failure occurs in the communication network according to the fourth embodiment shown in FIG.

  When the blocking is released, in the communication network 3, the layer 2 switch 41 relays the report message 56 from the terminal device 20P to the layer 2 switch 10. The layer 2 switch 42 relays the report message 54 from the terminal devices 20R and 20S to the layer 2 switch 41, and the layer 2 switch 41 relays the report message 54 from the layer 2 switch 42 to the layer 2 switch 10. . The layer 2 switch 10 relays the Report message 56 to the multicast router 30.

  Further, the layer 2 switch 10 relays the query message 55 from the multicast router 30 to the layer 2 switch 41. Then, the layer 2 switch 41 relays the query message (multicast address specific query message) 55 from the layer 2 switch 10 to the terminal device 20P and the layer 2 switch 42, and the layer 2 switch 42 receives the query message 55 from the layer 2 switch 10. Are relayed to the terminal devices 20R and 20S.

  Next, an operation procedure of the communication network according to the fourth embodiment will be described. Upon detecting a change in the network topology by the configuration control mechanism, each of the layer 2 switches 10, 41, and 42 transmits a TO_IN type Report message with an empty transmission source list to the router connection port. At this time, each layer 2 switch 10, 41, 42 starts a timer for maximum response waiting time (a timer for measuring the time until LLQT time elapses from a change in network topology), and has an entry timer, a source timer, and a filter timer. Shorten to LLQT.

  At this time, a timer may be provided to limit the number of Report messages transmitted so that a large number of Report messages transmitted by the layer 2 switches 10, 41, 42 do not arrive at the multicast router 30.

  When the multicast router 30 receives the Report message, the multicast router 30 transmits a Multicast Address Specific Query message. When the Layer 2 switch 10 receives the Query message from the multicast router 30 and the timer described above is running (until the timer value expires), all the ports (here, the Layer 2 switch 41) are connected. Relay the Query message.

  The layer 2 switch 41 receives the query message from the layer 2 switch 10 and relays it to all ports (here, the terminal device 20P and the layer 2 switch 42) in the same manner as the layer 2 switch 10.

  The layer 2 switch 42 receives the Query message from the layer 2 switch 41 from the port whose blocking has been released, and learns it as a router connection port. Then, similarly to the layer 2 switch 41, the layer 2 switch 42 relays the Query message to all ports (in this case, the terminal devices 20R and 20S).

  Each recipient responds with a Report message upon receiving these Query messages. Thereby, each layer 2 switch 10, 41, 42 updates the contents of the multicast table for each I / F unit. In addition, since various timer values are updated from a value equal to or lower than LLQT to MALI, a Report message is transmitted to the router connection port. Thereby, in the communication network 3, the multicast tree after the topology change is reconstructed.

  As described above, when a change in the network topology is detected, the various timer values are shortened to LLQT, and a timer for measuring the time until the LLQT time elapses after the change in the network topology is started. Then, a Report (TO_IN ({})) message is transmitted to prompt the router to send a Multicast Address Specific Query message, and the Multicast Address Specific Query message received during the timer start is relayed to all ports. It is possible to quickly confirm the presence of

  Thus, according to the fourth embodiment, when a change in the network topology is detected, a TO_IN type Report message with an empty transmission source list is transmitted to the multicast router 30, so the multicast relay tree after the change in the network topology Reconfiguration can be performed quickly.

  Further, it is not necessary to register in advance an upstream interface to which the multicast router 30 is connected and a downstream interface to which the multicast receiving terminal is connected, and each interface can be used in an arbitrary topology.

  Furthermore, since the Layer 2 switch itself does not generate a Query message in order to collect the recipient information, it only transmits a Report message so as to prompt transmission of the Query message from the multicast router 30, so that the terminal device receives it. There is no need to use undetermined addresses that are not guaranteed to be processed. As a result, it is not necessary to manage the address of the layer 2 switch so as not to participate in the Query sender selection process, and thus it becomes possible to easily manage the address.

  As described above, the data relay device according to the present invention is suitable for data relay of multicast data.

It is a figure which shows the structure of the communication network which has the layer 2 switch which concerns on Embodiment 1. FIG. 3 is a block diagram illustrating a configuration of a layer 2 switch according to Embodiment 1. FIG. 7 is a flowchart illustrating an operation procedure when the layer 2 switch according to the first embodiment receives a general query message. 7 is a flowchart illustrating an operation procedure when the layer 2 switch according to the first embodiment receives a Report message. 6 is a flowchart illustrating an operation procedure when the layer 2 switch according to the first embodiment receives a Specific Query message. It is a figure which shows the structure of the communication network which has the layer 2 switch which concerns on Embodiment 2. FIG. 10 is a flowchart illustrating an operation procedure of a router mode receiving unit when the layer 2 switch according to the second embodiment receives a Report message. 10 is a flowchart illustrating an operation procedure when a layer 2 switch according to the second embodiment receives a general query message. It is a figure (1) which shows the relationship between the message transmitted from a multicast entry state and a router connection port. FIG. 6B is a diagram (2) illustrating a relationship between a multicast entry state and a message transmitted from a router connection port. FIG. 10 is a diagram for explaining data relay when a receiver is added to the communication network according to the second embodiment. 10 is a flowchart showing an operation procedure when the layer 2 switch according to the second embodiment receives a Specific Query message. FIG. 10 is a diagram for explaining data relay of the communication network according to the third embodiment. It is a flowchart which shows the operation | movement procedure at the time of a Query receiving part receiving a Multicast Address Specific Query message. It is a figure which shows the structure of the communication network which has the layer 2 switch which concerns on Embodiment 4. FIG. FIG. 16 is a diagram for explaining data relay when a link failure occurs in the communication network shown in FIG. 15.

Explanation of symbols

1-3 Communication network 10, 40, 41, 42 Layer 2 switch 11J-11L, 16 I / F unit 12J-12L Router mode reception unit 13J-13L Multicast table storage unit 14 Reception group management table storage unit 15 Query reception processing unit 20J to 20L, 20P to 20S Terminal device 30 Multicast router 101, 102 Entry information

Claims (11)

In a data relay device that controls multicast relay by snooping messages that are used in the layer 3 multicast membership management protocol and transmitted and received between a multicast router and a receiving terminal,
A terminal-side communication unit that transmits and receives messages to and from the receiving terminal at an interface for each receiving terminal;
A router side communication unit for sending and receiving messages to and from the multicast router side;
A message indicating participation in multicast or leaving from multicast is transmitted to the multicast router and an inquiry message for inquiring about the multicast transmitted from the multicast router is relayed to the receiving terminal side, and the multicast router Control the multicast relay to and from the receiving terminal side , and collect and collect the receiver information on the receiving terminal based on the response message from the receiving terminal to the inquiry message A communication control unit for controlling the multicast relay using receiver information ;
With
The receiver information includes multicast information related to a multicast entry corresponding to each interface and information on a timer value of a management timer that manages each multicast entry,
The communication control unit determines whether or not to relay the leave confirmation message based on each timer value when receiving from the multicast router a leave confirmation message for confirming a receiver to leave among the inquiry messages. A data relay apparatus that relays the leave confirmation message from an interface corresponding to a timer value determined to relay the leave confirmation message when it is determined to relay the leave confirmation message. When the communication control unit receives a leave request message requesting leave from the multicast from the receiving terminal side, a criterion for determining whether to relay the leave confirmation message is a timer value corresponding to the leave request message; When the leave confirmation message is received from the multicast router side, the timer value is compared with the threshold value, and the timer value is handled based on the comparison result. the data relay apparatus according to claim 1, wherein said to determine whether to relay a leaving confirmation message to each multicast entries. When the communication control unit receives the leave confirmation message from the multicast router side, it determines whether to send a response message to the leave confirmation message to the multicast router side based on each timer value, 3. The data relay according to claim 2 , wherein when there is a timer value determined to transmit the response message, a response message corresponding to the multicast entry of the timer value is transmitted to the multicast router side. apparatus. The communication control unit receives a withdrawal request message requesting a leave from the multicast from the receiving terminal, a timer value corresponding to the withdrawal request message may be set to the threshold value, the from the multicast router side When receiving a leave confirmation message , each timer value is compared with the threshold value, and whether or not the response message is transmitted for each multicast entry corresponding to each timer value based on the comparison result The data relay device according to claim 3 , wherein: When the communication control unit receives the leave request message or the join request message for requesting participation in the multicast from the receiving terminal, the reception before receiving the leave request message or the join request message and after receiving the join request message 5. The data relay device according to claim 2 , wherein a determination is made as to whether or not to send a response message to the multicast router to the multicast router side based on a change in the user information. 6. . When the communication control unit receives the leave request message from the receiving terminal side, the communication control unit determines whether to send a response message to the multicast router to the multicast router side based on a change in state of the multicast entry, then when it is determined is described in any one of claims 2-5, characterized in that to send a response message and the detachable covers the entire specified source in the withdrawal request message to the multicast router-side Data relay device. When the communication control unit receives the leave request message or the join request message from the receiving terminal side, the communication control unit updates the timer value to a value according to a state change of the multicast entry, and changes before and after the timer value is updated. 7. The data relay device according to claim 5 , wherein whether or not to transmit the response message to the multicast router side is determined based on the data. The communication control unit has received the response message in the exclusion request mode in which the exclusion target of the transmission source is specified from the multicast transmission source list, and the interface of the terminal communication unit has specified the transmission source as a reception request target When the reception request mode response message is received, the reception request mode in which the timer value corresponding to the transmission source of the exclusion target specified in the exclusion request mode is set to the threshold value, and the reception request target is set to empty The data relay apparatus according to claim 2 , wherein the response message is transmitted to the multicast router side. When the communication control unit detects a change in the network topology of the network to which the own device is connected, the communication control unit transmits a response message in a reception request mode in which the reception request target is set to empty to the multicast router side. The data relay device according to claim 8 . When the communication control unit detects a change in the network topology of the network to which the own device is connected, the communication control unit sets the timer value of the management timer to the threshold value, and the timer value set to the threshold value expires 10. The data relay device according to claim 9 , wherein the leave confirmation message is relayed from all the interfaces of the terminal communication unit until. The data relay device according to any one of claims 2 to 10 , wherein the threshold is a maximum response waiting time of the leave confirmation message .

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