JP5556843B2 - Packet relay device - Google Patents

Description

  The present invention relates to a multicast network in which a transmission source server is limited, and particularly to a technique for connecting terminals that cannot specify a transmission source server.

  Multicast is a technique for simultaneously transmitting packets to a plurality of destinations on the Internet. Compared to sending a packet to a single destination multiple times, it can be sent to multiple destinations with a smaller amount of packets. Suitable for media communication.

Today, however, multicast networks are not so popular in the world. One of the major reasons is the complexity of multicast routing. Although multicast routing protocols such as DVMRP (Distance Vector Multicast Routing Protocol: RFC1075) and PIM-DM (Protocol Independent Multicast-Dense Mode: draft-ietf-pim-dm-new-v2-01.txt) are simple, There is a disadvantage that the network utilization efficiency is poor because multicast traffic is also sent to segments (network constituent units) that do not require transmission. Therefore, PIM-SM (Protocol Independent Multicast-Sparse Mode: RFC2362) that overcomes this drawback is usually used in the operation of multicast networks. Although PIM-SM allows multicast traffic to flow only to the minimum necessary segments, the overhead of multicast transmission tree calculation is large, so there are problems such as complicated protocols, difficult operation, and increased router load. (Asaeda, “New Communication Architecture Using Source Specific Multicast”, Information Processing, March 2002, Vol 43, No. 3, pp. 260-265)
A promising technique proposed to eliminate this complexity is Source-Specific Multicast. In conventional n-to-n multicast communication, a multicast receiving terminal sends a request to join a group. In source-limited multicast, when a multicast receiving terminal sends a request to join a group, Specify at the same time. The goal is to specify the multicast source as the receiver and limit the processing to 1-to-n multicast communication to make multicast routing simpler (draft-ietf-ssm-overview-00.txt) . Considering that many cases where multicast is used are streaming from a small number of servers, the user needs for multicast can be satisfied even if processing is limited to 1-to-n communication.

  The major difference between source-limited multicast routing and traditional multicast routing is that end-user terminals must specify their source server along with the multicast group address when joining the multicast group. . In order for end-user terminals to participate in a source-only multicast network, it is necessary to support the corresponding multicast group management protocol (IGMPv3 = Internet Group Management Protocol Version 3 for IPv4 and MLDv2 = Multicast Listener Discovery Version 2 for IPv6). is there. However, there are not many terminals that support IGMPv3 and MLDv2 today. In addition, IGMPv3 and MLDv2 have higher implementation costs than conventional source-unlimited multicast group management protocols, so it is expected that they will not be implemented in terminals that require low cost, such as information appliances.

  For this reason, some proposals have been made for connecting terminals that do not support IGMPv3 and MLDv2 to a source-limited multicast network. Cisco's IGMPv3 Lite incorporates an IGMPv3 conversion library with limited functionality into the end-user terminal application, so that even if the end-user terminal application does not support IGMPv3, it can participate in a source-limited multicast network through the conversion library. I am doing so. In Cisco's URD (URL Rendezvous Discovery), end users specify the source server to the router using HTTP (Hyper Text Transfer Protocol), and end users' terminals and applications do not support IGMPv3. Can also notify the router of a request to join the source-limited multicast network. In addition to these, by participating statically in a multicast group from a specific source for a line with the router itself, even if the end user terminal on that line does not support IGMPv3, Multicast traffic from the source can also flow (Cisco "Source-Specific Multicast with IGMPv3, IGMPv3lite, and URD feature module, Re lease 12.1 (5) T", http://www.cisco. com / univercd / cc / td / doc / product / software / ios121 / 121newft / 121t / 121t5 / dtssm5t.htm).

  One of the advantages of source-limited multicast is that network resources are prevented from being wasted due to multicast transmission from unspecified terminals because only multicast transmission from specific terminals is allowed. A proposal to further improve source-limited multicasting from this point of view is the multicast control protocol (draft-lehtonen-magma-mcop-00.txt) proposed by Sonera's Lehtonen. This system can collectively manage filtering of source-limited multicast participation requests by the multicast control server by inquiring whether the multicast control device can participate when the multicast relay device receives the source-limited multicast participation request. System.

"New Communication Architecture Using Source Specific Multicast", Information Processing, March 2002, Vol 43, No. 3, pp. 260-265

  There are two problems with the conventional technique for connecting a terminal that does not support source-limited multicast to a source-limited multicast network. One is that it can only be handled by end-user computers and applications. IGMPv3 Lite and URD have this drawback. In the case of IGMPv3 Lite, it is necessary to reconstruct the application using a conversion library. In the case of URD, the user needs to separately participate in the source-limited multicast network separately from the application. Therefore, compared with the source non-limitation type multicast network, the user's trouble is increased. This problem does not occur when the router itself participates in multicast multicast. However, in this case, even if there is no actual multicast participant, multicast traffic flows on the line where the router statically joins the multicast group. For this reason, the user is forced to be congested by unnecessary use of line bandwidth and unnecessary line cost.

  The present invention solves these two problems simultaneously. That is, it is an issue to be solved by the present invention to dynamically join or leave an end user terminal that supports only source-unlimited multicast to / from a source-limited multicast network without changing the setting. .

  In the present invention, the source non-restricted multicast group participation request sent from the terminal to the router is converted into a source limited multicast group participation request. For conversion, a multicast transmission source management table is used. This table manages the correspondence between the router, the multicast group address, and the multicast group management packet source terminal and the corresponding source server. This table is similar to the table used in the multicast control protocol.

  Using this table, the router accommodating the end user terminal converts the source non-restricted multicast group participation request into a multicast group participation request limited to the transmission source server permitted by the network administrator. Also, when a router inquires about the existence of participants in a source-limited multicast group, the router searches the same table to confirm that participation in the multicast group from that source is permitted, and then the source is not limited Queries whether there are participants in the multicast group.

  One aspect of the present invention is a packet relay apparatus that accommodates multicast client terminals, and requests for joining or leaving a multicast group from a multicast client terminal that cannot specify a multicast transmission source, and a multicast group that specifies the multicast transmission source It is a packet relay device that converts and processes the request to join or leave. In this relay apparatus, the multicast transmission source to be specified can be determined based on the address of the multicast client terminal and the address of the multicast group requested to join or leave. More specifically, using a correspondence table of a multicast group address, a multicast client terminal address, and a corresponding multicast source address, a request to join or leave a multicast group is sent from a multicast client terminal that cannot specify a multicast source. When this occurs, refer to the correspondence table, and specify the multicast source address of the entry that includes the address of the multicast client terminal that made the join or leave request and the address of the multicast group that was requested to join or leave. And When the multicast transmission source address in the correspondence table is “Don't care”, it may be processed as a request to join or leave a multicast group that does not specify a multicast transmission source. The correspondence table is built in the packet relay device, or is arranged in a separate device that is connected to the packet relay device via a line and accessible.

  Another aspect of the present invention is a packet relay apparatus that accommodates multicast client terminals, and a multicast client terminal that participates in a multicast group from a specific multicast transmission source exists in a certain network in response to a multicast participation inquiry. This is a packet relay device that can detect whether or not the multicast client terminal does not have a function of responding to a multicast participation inquiry for specifying a multicast transmission source. In this aspect, by searching a correspondence table of multicast group addresses, multicast client terminal addresses, and multicast source addresses corresponding to them, multicast client terminals participating in a multicast group from a specific multicast source are It can be detected whether it exists in a certain network. Another aspect of the present invention is a packet relay apparatus that accommodates multicast client terminals, and manages correspondence between multicast groups, addresses of terminals that are clients of the multicast group, and addresses that are multicast group transmission sources. The packet relay apparatus includes a management table, and uses this table to convert a source non-restricted multicast group join request into a source-restricted multicast group join request.

  Another aspect of the present invention is a method for converting a source-unlimited multicast group participation request into a source-limited multicast group participation request. Specifically, based on the multicast group address included in the request to join the multicast group from the terminal that supports only the transmission source unlimited multicast, and the line on which the join request has occurred, The transmission source server permitted by the network administrator is calculated from the multicast transmission source management table. The multicast router converts the request for participation in the multicast group not limited to the transmission source into a request for participation in the multicast group from the transmission source server permitted by the network administrator. In addition, when a multicast router periodically checks whether there is a terminal that participates in a multicast group from a specific source server in a network, the multicast group address and the line on which the join request has been generated are also included. At the same time, the transmission source server permitted by the network administrator for the multicast network is calculated in the multicast transmission source management table. If the calculated transmission source server does not match the transmission source server to be examined, the multicast router determines that there is no terminal participating in the multicast address from the transmission source server on the line. When the calculated transmission source server matches the transmission source server to be examined, the multicast router does not specify the transmission source server and determines whether there is a terminal participating in the multicast group on the line. Check in a similar way. Here, whether or not a corresponding terminal is found, that is, whether or not a terminal participating in a multicast address from the transmission source server exists on the line. Another aspect is that a multicast client, a multicast relay apparatus accommodating the multicast client, a multicast group address, a multicast client address, and a multicast source address corresponding to the corresponding table, a transmission from the multicast client. When a request to join an original unspecified multicast group occurs, the source address corresponding to the multicast group address is searched from the address of the multicast client that made the join request based on the multicast source address correspondence table. This is a method for converting a request to join a multicast group for which the transmission source is not specified into a multicast group participation request for which the transmission source is specified. . In addition, in a network composed of a multicast client, a multicast relay device accommodating the multicast client, a correspondence table of a multicast group address, a multicast client address, and a corresponding multicast source address, a specific source from the multicast relay device When an inquiry to join a multicast group from an IP address occurs on an interface with a multicast relay device, the multicast relay address from the address of the multicast relay device on the interface that sends the participation inquiry is supported based on the multicast source address correspondence table. This is a method of searching for a multicast source address defined by a network administrator.

  The scope of the present invention includes a network system that implements the above method and a network system that uses the above packet relay device.

  By using the present invention, an end user terminal that supports only source-unlimited multicast can participate in the source-limited multicast network only by changing the multicast router that directly accommodates the end-user terminal. Since the multicast router decides to join or leave the multicast based on the join request or leave request from the end user terminal, if the end user no longer needs the multicast traffic, the multicast traffic will not flow to the end user.

The block diagram which shows the whole image of the multicast routing which is the object of this invention. 1 is an overall block diagram of a source-limited multicast routing conversion apparatus using the present invention. 10 is a flowchart illustrating a method of converting a multicast participation participation input / output interface of a multicast router into a multicast group participation request limited to a transmission source server permitted by a network administrator from a source non-restricted multicast group participation request. 10 is a flowchart illustrating a method for converting an inquiry of a terminal participating in a source-limited multicast group into a source-unlimited multicast group participation request by a multicast participation leaving / input interface of the multicast router. It is the whole block diagram of the implementation which implemented the present invention by taking out the multicast participation leaving I / O interface out of the router. FIG. 5 is an overall block diagram of an implementation example in which the multicast transmission source management table is taken out of a router and the present invention is implemented. It is a whole block diagram of the implementation example which updates a multicast transmission source management table automatically by the request from a user.

  Embodiments of the present invention will be specifically described below.

  FIG. 1 shows an overview of source limited multicast routing which is the subject of the present invention. FIG. 2 is an overall view of a source-limited multicast routing conversion apparatus using the present invention. FIG. 3 is a flowchart illustrating a method in which an edge router in a location that accommodates a terminal in a multicast network converts a non-source limited multicast group participation request into a multicast group participation request limited to a transmission source server permitted by a network administrator. FIG. 4 is a flowchart showing a method for converting an inquiry of a terminal participating in a source limited multicast group into a source non-limited multicast group participation request. 5, 6 and 7 show another embodiment of the present invention.

  First, a general multicast communication implementation method will be described with reference to FIG. When the multicast client terminal 100 participates in the multicast group, the multicast client terminal 100 transmits a request to join the multicast group to the multicast router 110 in a position where the terminal 100 is directly accommodated. A multicast group management protocol such as IGMPv2 or MLDv1 is used in the case of conventional source-unlimited multicast, and a multicast group management protocol such as IGMPv3 or MLDv2 is used in the case of source-limited multicast. The multicast router 110 receives a request to join the multicast group at the multicast group management packet processing unit 114 via the line 116. The multicast group management packet processing unit 114 notifies the multicast route control unit 112 of the received multicast participation request. The multicast route control unit 112 is a multicast router 121 in the transmission source direction among adjacent multicast router groups (in the case of source-limited multicast, it is a next hop router for reaching a designated source address by unicast. Source unrestricted) In the case of type multicast, it is confirmed that there has been a request to join the multicast group for the next hop router to reach the address called the rendezvous point defined by the network administrator corresponding to the group address by unicast. Notice. A multicast routing protocol such as PIM-SM is used for the group join / leave notification between the routers. At the same time, the multicast route control unit 112 sends a packet to the packet relay unit 118 from the router 121 to the multicast group (in the case of source-limited multicast, a condition from a specified source is further added) Is added to the line 116 where the multicast client terminal 100 is located.

  By repeating this notification work and adding packet relay settings, all the multicast routers located between the multicast client terminal and the transmitting terminal in the network 120 can know the multicast route information (in the case of source-unlimited multicast, multicast Since only the multicast router between the client terminal and the rendezvous point multicast router knows the multicast route information, the multicast router between the rendezvous point and the sending terminal does not necessarily know the multicast route information. Since it is assumed that the location of the point is known, it is possible to reach the rendezvous point corresponding to the multicast group from the transmitting terminal. All the routers at the end can know the multicast route information, so when the multicast transmission server 130 in the multicast network 120 communicates with the multicast group, the terminal 100 passes through the multicast routers 122, 121, and 110. Communication will also flow.

  The multicast group management unit 114 of the multicast router 110 periodically checks whether there is a multicast participant on the line 116 where the terminal 100 exists in order to grasp whether the terminal 100 is participating in the multicast group. . When the terminal 100 is participating in the multicast group, the terminal 100 returns a request for participation in the multicast group in response to the confirmation inquiry. The protocols used for these exchanges are IGMPv3 and MLDv2 in the case of a source-limited multicast inquiry, and IGMPv2 and MLDv1 in the case of a source-unlimited multicast. If the terminal 100 has not joined the multicast group, the terminal 100 does not reply anything. Therefore, when the multicast participation request is interrupted for a certain period of time on the line 116, the multicast router 110 determines that there are no terminals participating in the multicast group on the line 116, and the adjacent multicast router 121 in the transmission source direction receives the multicast group. A request to leave is sent using a multicast routing protocol such as PIM-SM.

  At the same time, the multicast route control unit 112 sends a packet to the packet relay unit 118 from the router 121 to the multicast group (in the case of source-limited multicast, a condition from a specified source is further added) Delete the setting to relay to the network where the multicast client terminal 100 is located.

  By repeating this notification work and packet relay setting deletion, the loss of route information to the multicast group in the edge router 110 spreads to all multicast routers in the network 120, so even if the multicast transmission server 130 communicates to the multicast group, the terminal The communication will not reach 100.

  In the source non-restricted multicast, the join request and the leave request advertised to the entire network 120 via the multicast router 110 from the multicast client terminal 100 include only the multicast group address, whereas In the case of the participation request, the terminal 100 advertises the multicast transmission server 130 address and multicast group address pair. Therefore, in the case of source-limited multicast, route control can be performed in the network 120 so that only traffic from the designated multicast transmission server 130 reaches the multicast client terminal 100. Traffic to the same multicast address from the multicast transmission server 131 that is not specified reaches the multicast client terminal 100 in the same way as from the multicast transmission server 130 in the source-unlimited multicast. On the other hand, in source-limited multicast, the method of relaying multicast packets from the source server 131 does not exist in the network 120. Therefore, if the source server is different, routing is controlled so that traffic does not reach the request source even if the source server is different. Because it is done.

  In order to realize source-limited multicast, the source server is set together with the multicast group address in both the communication between the multicast client terminal 100 and the multicast router 110 and the communication between the multicast router 110 and the adjacent multicast router 122. It is necessary to advertise, but for the latter communication between the routers, the information of the source server can be exchanged by the existing multicast control protocol PIM-SM (specified by Protocol Independent Multicast Sparse Mode, IETF RFC2362) . The multicast group management protocol is used for communication between the former terminal and the multicast router. However, as explained in the section of the prior art, it is not necessary to implement the multicast group management protocol that allows all terminals to notify the source server address. I don't mean. Therefore, in order to realize source limited multicast, a multicast group management method between a terminal and a multicast router becomes a problem.

  In IGMPv2 and MLDv1, which are used for multicast group management between terminals and multicast routers, three types of packets are defined: join request (Join), join inquiry (Query), and leave request (Leave). It is used. Therefore, it is sufficient to convert these three types of source-unlimited multicast group management packets into corresponding packets of source-limited multicast. Hereinafter, a method for converting these three types of packets will be described.

  A method for converting a source non-limited multicast join request (Join) and a leave request (Leave) into a source limited multicast will be described with reference to FIG. The multicast transmission source management table 220 manages the correspondence of the triple group of the multicast group address column 222, the multicast participation / leave request generation source column 223, and the multicast transmission source server address column 224. In this embodiment, it is assumed that the router administrator has previously filled the contents of the multicast transmission source table 220 with appropriate contents.

  Based on FIG. 3, a method by which the multicast group management packet conversion unit 210 of the multicast router 110 converts the source non-limited multicast participation request from the line 116 to the source limited type will be described. When receiving the multicast participation request from the terminal 100 (step 300), the multicast group management packet conversion unit 210 determines whether the request is a source limited multicast participation request or a source non-limited multicast participation request (step 310). In the case of IPv4 IGMP and IPv6 MLD, identification is possible based on the packet length. In the case of the source limited type, the multicast group management packet converting unit 210 transmits the source limited multicast participation request as it is to the multicast group management packet processing unit 114 (step 350). If the source is not limited to the source, the multicast group management packet conversion unit 210 determines that the source address of the multicast participation request, that is, the set of the address of the terminal 100 and the multicast group address included in the multicast participation request, It is checked whether there is an entry in the multicast source management table 220 that matches both of the multicast group address fields 222 (step 330). If there is no entry, it means that the request for participation in the multicast is rejected by the network administrator, so the multicast group management packet conversion unit 210 ignores the participation request (step 340). If there is an entry, the multicast group management packet conversion unit 210 checks the content of the calculated transmission source server. If the content is “don't care”, the multicast group join request is to be processed as a source non-restricted type, and is passed to the multicast group management packet processing unit 114 as it is (step 360). In other cases, the multicast participation request from the source address detected in step 330 is passed to the multicast group management packet processing unit 114 (step 370). In exactly the same manner as above, the multicast group management packet conversion 114 of the multicast router 110 converts the source non-limiting multicast leaving request from the line 116 into the source limited type.

  Based on FIG. 4, a method in which the multicast group management packet conversion unit 210 of the multicast router 110 converts the source-limited multicast participation inquiry (Query) from the multicast route control unit 112 into a source non-limited type will be described. When a multicast participation inquiry for the line 116 from the multicast route control unit 112 is received via the multicast group management packet processing unit 114 (step 400), the multicast group management packet conversion unit 210 determines whether the inquiry is a source limited multicast participation inquiry. It is determined whether it is a source non-limited multicast participation inquiry (step 410). If the source is not limited, the multicast group management packet conversion processing unit 210 transmits the multicast participation inquiry as it is to the designated line 116 (step 420). In the case of the source limited type, an entry in which the multicast group address field 222 and the multicast group management packet source field 223 respectively match the multicast address included in the inquiry and the address of the line 116 to which the inquiry is sent is the multicast source management table. Whether it is included in 220 is checked (step 430). If there is no corresponding entry, it means that the multicast group has been refused operation by the network administrator, so the multicast group management packet conversion unit 210 does not send a participation inquiry (step 440). If there is an entry, it is checked whether or not the address in the transmission source server column 224 of this entry includes the source address in the source limited multicast participation inquiry (step 450). If not included, it means that the request for participation in the multicast has been rejected by the network administrator, so the multicast participation / exit management unit does not send an inquiry (step 440). If it is included, the source address is approved by the network administrator, so the multicast group management packet translation unit 210 sends a non-source limited inquiry to the multicast address included in the inquiry. It may be transmitted to 116 (step 460).

  In the present invention, the multicast group management packet processing unit 114 of the multicast router 110 converts the source non-limiting multicast group management packet into a source limited multicast group management packet. Therefore, in the multicast route control unit 112 of the multicast router 110, it just looks as if a terminal supporting source limited multicast exists on the line 116. Therefore, the route control between the multicast router 110 and the adjacent multicast router 122 does not require any change according to the present invention. Therefore, only the multicast router 110 accommodating the terminal 100 in the multicast network 120 needs to be changed in the present invention.

  In the present invention, the user cannot select any multicast transmission source server. In that respect, it is not a conversion technique for making source-unlimited multicast terminals completely compatible with source-limited multicast. However, as described in the section of the prior art, source-limited multicast is intended for multicast communications from a few servers such as streaming, and the streaming server is generally operated by a network administrator. There are few practical problems.

  It will be described below with reference to FIGS. 5, 6 and 7 that the present invention can be realized in forms other than the embodiment described above.

  In the above embodiment, the function of the multicast group management packet processing unit 114 is incorporated in the multicast router 110. FIG. 5 shows an embodiment in which the function of the multicast group management packet processing unit 114 is removed. In this case, the multicast group management packet conversion apparatus 500 passes the packets other than the multicast group management packet as they are between the terminal 100 and the multicast router 110. When a multicast management packet is input from the line 501 or 502, the multicast group management packet conversion unit 210 converts the packet by the following processing, and then outputs the packet to the line 502 or 501. That is, the multicast join request packet and the leave request packet are converted into a source-limited multicast compatible version by the process of FIG. 3, and the multicast join / leave inquiry packet input from the multicast router 110 is converted into a source non-limited multicast compatible version by the process of FIG. It will function as a protocol converter.

  2 and FIG. 5 is based on the premise that the multicast transmission source management table 220 exists in the multicast router 110. FIG. 6 introduces an embodiment in which the multicast transmission source management table is separated from the multicast router 110. When performing the search processing of the table 220 in the processing of FIGS. 3 and 4, the internal table is drawn in the embodiment of FIGS. 2 and 5, but in FIG. A similar search is realized by making an inquiry. Thereby, it is possible to collectively manage the multicast transmission source management table of each multicast router. In this case, each multicast router makes an inquiry to this server to search the multicast transmission source management table 220 described above. It is sufficient to use an existing network database search protocol such as Radius (RFC2865) as the communication protocol used for the inquiry. Figure 7 is an overall view of an implementation example in which the multicast source management table is automatically updated in response to a request from the user. In the embodiment of FIGS. 2, 5, and 6, it is assumed that the multicast source management table 220 is input separately by the network administrator, but multicast source management is realized by implementing the present invention as shown in FIG. The settings in Table 220 can be semi-automated. In general, in the case where paid contents are distributed by multicast, the contract management server 700 needs to manage a contract for using paid contents with the user. The contract ledger 710 managed by the contract management server 700 includes user network information 711 and a contracted session (= a combination of a transmission source server and a multicast group address) 712, and the contents are networked to the multicast transmission source management server 600. By reflecting through the contents, it is also possible to automatically add and delete the contents of the multicast transmission source management table 220 according to a request from the user. As a protocol used for communication from the contract management server 700 to the multicast transmission source management server 600, it is sufficient to use an existing protocol such as HTTPS having a security function that prevents illegal update of the multicast transmission source management table 220. .

100 multicast client terminals
110 Multicast router
112 Multicast route controller
114 Multicast group management packet processor
116 Multicast router line
120 network
122 Multicast router
130 Multicast sending server
131 Multicast sending server
210 Multicast group management packet converter
220 Multicast source management table
222 Multicast address field
223 Multicast group management packet source column
224 Multicast source server address field
500 Multicast group management packet converter
600 Multicast source management server
700 Contract management server.

Claims (10)

  A packet relay device accommodating a multicast client terminal,
A first request to join or leave a multicast group that includes a multicast group designation according to the first multicast group management protocol and no multicast source designation, or a multicast group designation and multicast according to the second multicast group management protocol A receiver for receiving a second request to join or leave a multicast group including a designation of a transmission source from the multicast client terminal;
When the first join or leave request is received, a multicast source is specified based on a multicast group designation included in the first join or leave request, and the specified multicast source and the first When the second participation or leaving request is received, the multicast transmission source included in the second joining or leaving request is generated. And a request generator for generating a join or leave request including designation of a multicast group,
A multicast packet relay apparatus comprising: a transmission unit that transmits the generated join or leave request to another relay apparatus using a multicast routing protocol. The multicast packet relay device according to claim 1,
The multicast packet relay device, wherein the first multicast group management protocol is IGMPv2 or MLDv1, the second multicast group management protocol is IGMPv3 or MLDv2, and the multicast routing protocol is PIM-SM. The multicast packet relay device according to claim 1,
The request generation unit specifies a multicast source designation corresponding to a multicast group designation included in the first join or leave request from an association between a multicast group and a multicast source. Multicast packet relay device. The multicast packet relay device according to claim 3,
The association includes a correspondence between a group identifier that specifies a multicast group and a transmission source identifier that specifies a multicast transmission source or an identifier that does not specify a transmission source. The multicast packet relay device according to claim 4,
A storage unit for holding the association;
The transmission unit refers to the association, and based on the designation of the multicast group included in the first join or leave request, extracts a transmission source identifier or an identifier that does not specify a transmission source,
When a transmission source identifier that identifies a multicast transmission source is extracted, a join or leave request is transmitted to another relay device toward the multicast transmission source specified by the transmission source identifier,
A multicast packet relay device that transmits the generated join or leave request to another relay device toward a predetermined rendezvous point when an identifier that does not specify a multicast transmission source is extracted. 6. The multicast packet relay device according to claim 3, wherein the request generation unit holds an association between a multicast group and a multicast transmission source, and is included in the first join or leave request. A multicast packet relay device that terminates relay processing for the multicast packet when a multicast group corresponding to the designation of the multicast group is not included in the association. The multicast packet relay device according to any one of claims 1 to 3,
When the request generation unit does not specify the multicast transmission source based on the specification of the multicast group included in the first join or leave request, the transmission unit specifies the multicast transmission source to another relay device. Send join or leave requests that do not contain
In the request generation unit, when the multicast transmission source is specified based on the designation of the multicast group included in the first joining or leaving request, the route search is performed based on the specification of the specified multicast transmission source. A multicast packet relay device that transmits the generated join or leave request to another relay device. A multicast packet relay device according to any one of claims 1 to 7,
A multicast packet relay device further comprising a determination unit for determining whether to comply with a first multicast group management protocol or a second multicast group management protocol based on a packet length of a join or leave request received by the reception unit. A multicast packet relay device located between a multicast distribution server that is a multicast transmission source and a terminal that is a multicast distribution request source,
A receiving unit for receiving a join or leave request including designation of a multicast group according to a multicast group management protocol generated by the terminal;
A discriminator for discriminating whether or not a request for multicast transmission is included in the join or leave request received by the receiver;
As a result of determination by the determination unit, when the multicast transmission source designation is included in the join or leave request received by the reception unit, the join or leave request including the multicast transmission source designation is sent to the multicast distribution server. Processing to send to the relay device,
As a result of determination by the determination unit, when a multicast transmission source is not specified in the join or leave request, a multicast transmission source is specified by an identifier associated in advance with a multicast group included in the join or leave request Includes a first process for transmitting a join or leave request including designation of the specified multicast transmission source to another relay device toward the multicast distribution server, and a multicast group included in the join or leave request in advance. A second process of transmitting a join or leave request not including the designation of the multicast source to another relay device when the multicast source is not specified by the associated identifier; The multicast group included in the withdrawal request If no associated Les identifier and a transmission control unit including a third and processing, to terminate the relay processing related to the join or leave request, the multicast packet relay apparatus characterized by. A packet relay device accommodating a plurality of multicast client terminals,
  When the first request to join or leave the multicast group not including the designation of the multicast transmission source according to the first multicast group management protocol is received from the accommodated multicast client terminal, the first join or leave request is sent , Converting the multicast source specified by the multicast group included in the first join or leave request into a request to join or leave the specified multicast group, and forwarding according to the multicast routing protocol,
  When a second join or leave request to / from a multicast group including designation of a multicast source according to the second multicast management group protocol is received from the other multicast client terminals accommodated, the first request is sent without performing the conversion. A packet relay device having a processing unit for transferring a second join or leave request according to a multicast routing protocol.

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