JP4099771B2 - IP multicast routing system and IP multicast routing method - Google Patents

Description

  The present invention relates to an IP multicast control technique for copying an IP packet in an IP packet communication network and distributing the same IP packet to a plurality of destinations in an IP packet communication network.

  As a conventional IP multicast route control method, there are an IP multicast control technology (referred to as technology 1) proposed by the present applicant and Non-Patent Document 1.

  In the technique 1, when a distribution source database is provided, a combination of an IP multicast address and a distribution source IP address is registered in advance, and the host accommodating router receives a multicast distribution request in which only the IP multicast address is written, The distribution source database is inquired about the distribution source IP address, and the host accommodating router makes a multicast distribution request to the acquired distribution source IP address, so that the distribution source is known and the path control is realized.

  Further, in Non-Patent Document 1, when the host does not know the distribution source IP address, the host accommodating router that has transmitted the multicast distribution request describing only the IP multicast address to the host accommodating router and received the multicast distribution request is The multicast distribution request is transmitted to the adjacent multicast relay router in the direction of the rendezvous point router.

  On the other hand, the multicast traffic is received by the rendezvous point (multicast relay router), and when the multicast distribution request arrives at the rendezvous point, the multicast traffic traces the direction in which the multicast distribution request is received in reverse and accommodates the host. Arrives at the router. As described above, multicast route control is realized.

RFC2362 "Protocol Independent Multicast-Sparse Mode (PIM-SM): Protocol Specification"

  However, as a first problem, the technique 1 has a problem that a combination of an IP multicast address and a distribution source IP address must be registered in advance in the distribution source database. In this case, when the distributor wants to perform multicast distribution, it must be registered in the distribution source database, and there is a problem that it takes time until the distribution becomes possible.

  As a second problem, in Non-Patent Document 1, the association between the IP multicast address and the IP address of the distribution server is performed by the rendezvous point router as described above, and the multicast distribution request packet Since multicast packets are concentrated on one rendezvous point router, the rendezvous point router becomes a heavy load and becomes a bottleneck of the IP network.

  The object of the present invention is to solve the above problems and improve the operability by automatically registering the distribution server in the IP multicast route control, and improve the reliability of the IP network by eliminating the bottleneck on the route. To provide IP multicast routing technology.

  In order to solve the first problem of this problem, in the present invention, the distribution server accommodating router that has received the multicast packet autonomously sets the combination of the IP multicast address and the distribution source IP address to the distribution source database. Notify and register.

  In order to solve the second problem, an apparatus having a rendezvous point function is disconnected from the packet transfer path. By installing a distribution source database with functions equivalent to the rendezvous point independently from the packet path, even if the distribution source database breaks down or becomes congested, each router operates normally and unicast forwarding is normal. Will continue.

  Furthermore, automatically deleting the distribution source IP address whose distribution has been stopped in the distribution source database is effective in that an invalid distribution request is not transferred to the IP network.

  Also, limiting the range of IP multicast addresses registered in the distribution source database is effective in preventing multicast distribution that is not permitted by the network.

Further, limiting the distribution source IP addresses registered in the distribution source database is effective in preventing unauthorized distribution using a regular IP multicast address.
Moreover, restricting the distribution server accommodating routers that accept the multicast address set is effective in preventing unauthorized distribution by illegally connecting routers.

More specifically, the present invention has the following configuration.
(1) An IP multicast route control system in an IP multicast network composed of at least a host, a host accommodating router, a distribution server, and a distribution server accommodating router, wherein the IP multicast address and the IP of the multicast distribution server A distribution source database for storing a combination of addresses (multicast address set) is provided. When the distribution server accommodating router receives a multicast packet from the distribution server, the combination of the destination IP address and the transmission source IP address described in the multicast packet To the distribution source database as a multicast address set, and the distribution source database registers the multicast address set when the multicast address set is notified, And to notify all the multicast address set corresponding to the specified IP multicast address when receiving a multicast address set request specifying the IP multicast address from the list or host housed router to a host or host receiving router.

(2) In the above (1), the distribution source database receives the means for storing the reception state for each registered multicast address set and once within a predetermined time period among the registered multicast address sets. Means for deleting a multicast address set for which there is no medium notification, and the distribution server accommodating router monitors the reception state of the multicast packet and periodically notifies the distribution source database of the multicast address set of the multicast packet being received. Prepare.

(3) In the above 8 (2), the means for monitoring the reception state of the multicast packet and periodically notifying the multicast address set of the multicast packet being received includes a table for storing the multicast address set and a reception flag; If the distribution server accommodating router obtains the IP header information of the multicast packet received between the timer activation and the timeout, and the multicast address set of the received multicast packet exists in the table If the reception flag is being received, and the multicast address set is not present in the table, the multicast address set is registered in the table and the reception flag is being received. After deleting and notifying the distribution source database of the multicast address set whose reception flag is being received, the reception flag is changed to non-reception.

(4) In the above (2), the means for monitoring the reception state of the multicast packet of the distribution server accommodating router and periodically notifying the multicast address set of the multicast packet being received comprises a packet number counter and receives the received data The packet is counted by the packet number counter, and information on the destination IP address and the source IP address is periodically acquired. If the destination address is an IP multicast address, the information is notified to the distribution source database.

(5) In the above (3) or (4), the means for monitoring the reception state of the multicast packet and periodically notifying the multicast address set of the multicast packet being received stores the range of the IP multicast address to be notified Means for notifying the distribution source database when the destination IP address of the acquired data packet or the IP multicast address of the multicast address set registered in the table is an IP multicast address in the stored range.

(6) In the above (5), the means for monitoring the reception state of the multicast packet and periodically notifying the multicast address set of the multicast packet being received comprises means for storing the range of the distribution source IP address to be notified. When the destination IP address of the acquired data packet or the IP multicast address of the multicast address set registered in the table is the distribution source IP address in the stored range, the distribution source database is notified.

(7) In any one of (2) to (6), the means for storing the reception state for each registered multicast address set includes a table for storing the multicast address set and the expiration date, and the distribution source database is: When the multicast address set is notified from the distribution server accommodating router within the stored expiration date, the expiration date for the notified multicast address set is updated, or the expired multicast address set is deleted To do.

(8) In the above (7), for each registered multicast address set, the means for storing the reception state includes means for storing the range of IP multicast addresses to be registered, and the distribution source database registers the multicast address set. In this case, the multicast address set is registered only when the IP multicast address is within the stored range.

(9) In the above (7) or (8), the means for storing the reception state for each registered multicast address set comprises means for storing a range of distribution source IP addresses to be registered. When registering an address set, the multicast address set is registered only when the distribution source IP address is within the stored range.

(10) The distribution source database according to any one of (1) to (9) includes means for storing an IP address of a distribution server accommodating router that accepts a multicast address set, and the distribution source database includes a multicast address set notification. Is received, the source IP address of the notification packet is confirmed, and if it is a stored IP address of the distribution server accommodating router, it is accepted, and if it is not stored, the notification is discarded.

(11) Consists of at least a host, a host accommodating router, a distribution server, a distribution server accommodating router, a distribution source database that stores a combination of an IP multicast address and an IP address of the multicast distribution server (multicast address set) When a distribution server accommodating router receives a multicast packet from a distribution server, the combination of the destination IP address and the transmission source IP address described in the multicast packet is multicast. A step of notifying the distribution source database as an address set, and the distribution source database registering the multicast address set when the multicast address set is notified , Comprising the step of notifying all the multicast address set corresponding to the specified IP multicast address when receiving a multicast address set request specifying the IP multicast address from the host or host housed router to a host or host receiving router.

(12) In the above (11), the distribution source database stores the reception state for each registered multicast address set, and the distribution server accommodating router monitors the reception state of the multicast packet and receives the multicast being received. The step of periodically notifying the distribution source database of the multicast address set of the packet, and the distribution source database includes a multicast address set for which no notification of reception is received within a predetermined time period from among the registered multicast address sets. A step of deleting.

  According to the present invention, the distribution server can be automatically registered in the IP multicast route control, so that the operability is improved and the bottleneck is eliminated on the route and the reliability of the IP network is improved.

  Embodiments of the present invention will be described in detail with reference to the drawings.

Example 1
A first embodiment of the present invention will be described with reference to the drawings.
1 is a diagram illustrating a network configuration example of the first embodiment, FIG. 2 is a diagram illustrating a table configuration example of a distribution source database used in the first embodiment, and FIG. 3 is a diagram illustrating an operation example 1 of the first embodiment. FIG. 4 is a diagram illustrating an operation example 2 of the first embodiment.

  As shown in FIG. 1, this embodiment includes a distribution source database 1, a distribution server accommodating router 2, a distribution server 3, a host accommodating router 4, a host 5, and a multicast relay router 6. The distribution source database 1 and the distribution server accommodating router 2 have tables 11 and 21, respectively.

  The distribution source database 1 is connected to the distribution server accommodating router 2 and the host accommodating router 4 through the IP network, and may also be connected to the host 5 through the IP network.

  A plurality of distribution server accommodating routers 2, host accommodating routers 4, and multicast relay routers 6 may be installed. However, the IP network configuration is not intended to limit the present invention, and in order to clarify the features of the present invention, In the embodiment, each case is described as one.

  The configuration of the table 11 of the distribution source database 1 according to the first embodiment includes, for example, combination information of an IP multicast address and a distribution source IP address, that is, a multicast address set, as indicated by 11a in FIG.

  A plurality of distribution source IP addresses corresponding to one IP multicast address can be registered. The version of the IP address to be registered may be IP version 4 or IP version 6, and does not limit the version of the present invention.

Next, an operation example 1 will be described with reference to FIG.
In FIG. 3, when the distribution server accommodating router 2 receives a packet whose destination IP address is multicast from three directly connected distribution servers (a), the distribution server accommodating router 2 uses the destination IP address of the packet to the distribution source database 1. A certain IP multicast address and a distribution source IP address which is a transmission source IP address of the packet are notified as a multicast address set (b).

  At this time, whether the received packet is received from the directly connected distribution server as a function of the distribution server accommodating router or remotely as a function of the relay router is determined by the IP multicast packet It can be determined whether the source IP address is an IP address of a directly connected subnet.

  Further, when the networks are interconnected, if the distribution server accommodating router function is set for the interconnected interface, the interface can be operated as the distribution server accommodating router. Such a method is an obvious operation. In the description of the present invention, when the distribution server accommodating router indicates that the IP multicast packet is received, the above-described operation indicates that the distribution server accommodating router has received the IP multicast packet. means.

  When the distribution source database 1 is notified of the combination information of the IP multicast address and the distribution source IP address from the distribution server accommodating router 2, the distribution source database 1 registers the multicast address set (c).

  At this time, when one or more other distribution source IP addresses are already stored for the IP multicast address, the distribution source IP address is added.

  When the host 5 desires multicast distribution, the host 5 issues a multicast address set request specifying the IP multicast address to the distribution source database 1 (d), and multicast distribution specifying the multicast address set (e) notified as a response. The request is transmitted in the direction of the distribution source IP address (f).

  The multicast distribution request transmitted in the direction of the distribution source IP address reaches the distribution server accommodating router 2 (g), and the multicast packet traces the transfer direction of the multicast distribution request in reverse to reach the host (h).

Next, an operation example 2 will be described with reference to FIG.
The operation example 2 differs from the operation example 1 described above in the operation of the multicast address set request. In the operation example 2, as shown in FIG. 4, when the host 5 issues a multicast distribution request not specifying the distribution source IP address (i), the host accommodating router 4 sends the IP multicast address to the distribution source database 1. Is issued (j), and a multicast distribution request specifying the multicast address set (k) notified as a response is transmitted in the direction of the distribution source IP address (l).

  The multicast distribution request transmitted in the direction of the distribution source IP address reaches the distribution server accommodating router 2, and the multicast packet reaches the host by tracing back the transfer direction of the multicast distribution request (m).

(Example 2)
Next, Embodiment 2 of the present invention will be described with reference to the drawings.
FIG. 5 is a diagram showing an operation example of Embodiment 2 of the present invention. The network configuration in the second embodiment is the same as that of FIG.

  In FIG. 5, when the distribution server accommodating router 2 receives a packet whose destination IP address is multicast from the distribution server 3 within a certain time (n), it notifies the distribution source database of the multicast address set of the received packet. (O).

  When the distribution source database 1 receives a multicast address set not registered in the table 11 from the distribution server accommodating router 2, the distribution source database 1 registers the received multicast address set (p) and starts a monitoring timer for the multicast address set. (Q).

  When the distribution source database 1 receives the multicast address set registered in the table from the distribution server accommodating router, the distribution source database 1 updates the monitoring timer for the address list.

  Further, when the monitoring timer times out (r), the distribution source database 1 deletes the time-out address set (s).

(Example 3)
Next, Embodiment 3 of the present invention will be described with reference to the drawings.
FIG. 6 is a diagram showing a table configuration example of the distribution server accommodating router according to the third embodiment of the present invention.
As shown in FIG. 6, the distribution server accommodating router table 21a includes an IP multicast address, a distribution source IP address list, and a reception flag. The reception flag is a flag indicating whether the distribution server accommodating router has received or has not received a multicast packet having the combination within a predetermined time.

Next, an operation example of the distribution server accommodating router according to the third embodiment of the present invention will be described with reference to FIG.
In FIG. 7, when the distribution server accommodating router 2 receives a packet whose destination IP address is multicast (step S1), the distribution server accommodating router 2 sets the destination IP address as the IP multicast address and the source IP address as the distribution source IP address. (Step S2), referring to the table 21, and if the multicast address set is not registered (step S3: N), the reception flag is registered in the table 21 as being received (step S4), and the distribution source A multicast address set is notified to the database 1 (step S5). If the multicast address set has already been registered (step S3: Y), the reception flag is being received (step S6).

  In addition, in the distribution server accommodating router 2, when the timer is operating and time-out occurs (step S7), the multicast address set whose reception flag is not received is deleted from the multicast address set in the table (step S9, Only the multicast address set whose reception flag is reception is added to the multicast address set list (step S11), and the reception flag is not received (step S12).

  When the above processing is completed for all registered multicast address sets (steps S8 and S13), the distribution source database 1 is notified of the multicast address set list (step S14), and the multicast address set list is emptied ( Step S15), the timer is restarted (Step S16).

Example 4
Next, a fourth embodiment of the present invention will be described with reference to the drawings.
FIG. 8 is a diagram illustrating an operation example of the distribution server accommodating router according to the fourth embodiment.
In FIG. 8, in the distribution server accommodating router 2, the IP address information collection interval is set to once per X packet (step S21). Here, X is an integer of 1 or more.
When receiving the IP packet (step S22), the distribution server accommodating router 2 adds a packet interval count counter (step S23).

  If the value of the counter is X (step S24: Y), the destination IP address is confirmed (step S25). If the destination IP address is an IP multicast address (step S25: Y), a multicast address set (step S26). Is notified to the distribution source database (step S27), and the value of the counter is reset to 0 (step S28).

  If the counter value is other than X after adding the packet interval count counter (step S24: N), and if the destination IP address is not an IP multicast address (step S25: N), notification processing for the packet Do not do.

(Example 5)
Next, Embodiment 5 of the present invention will be described with reference to the drawings.
FIG. 9 is a diagram illustrating an operation example of the distribution server accommodating router according to the fifth embodiment.
In FIG. 9, in the distribution server accommodating router 2, an IP multicast address range to be notified to the distribution source database 1 is set in advance (step S31).

When the distribution server accommodating router 2 receives the IP packet (step S32), the distribution server accommodating router 2 adds a packet interval count counter (step S33).
If the value of the counter is X (step S34: Y), the destination IP address is confirmed (step S35). If the IP multicast address is within a preset range (step S35: Y), the multicast address set (step S36). ) Is notified to the distribution source database (step S37). Other operations are the same as those in the fourth embodiment.

(Example 6)
Next, Embodiment 6 of the present invention will be described with reference to the drawings.
FIG. 10 is a diagram illustrating an operation example of the distribution server accommodating router according to the sixth embodiment.
In FIG. 10, in the distribution server accommodating router 2, an IP multicast address range to be notified to the distribution source database 1 is set in advance (step S41).

  When the distribution server accommodating router 2 receives the IP packet (step S42), the distribution server accommodating router 2 adds a packet interval count counter (step S43).

  If the counter value is X (step S44: Y), the destination IP address is confirmed (step S45), and if it is an IP multicast address (step S45: Y), the source IP address is confirmed (step S46). If the IP address is within a preset range (step S46: Y), the multicast address set (step S47) is notified to the distribution source database (step S48). Other operations are the same as those in the fourth embodiment.

(Example 7)
Next, Embodiment 7 of the present invention will be described with reference to the drawings.
FIG. 11 is a diagram illustrating a table configuration example of a distribution source database according to the seventh embodiment. As shown in the figure, the distribution source database 11b is composed of a multicast address set and an expiration date. The expiration date means the expiration date of the multicast address set.

FIG. 12 is a diagram illustrating an operation example of the seventh embodiment of the present invention.
In FIG. 12, when the distribution source database 1 receives a multicast address set notification from the distribution server accommodating router 2 (step S51), if the notified multicast address set is not registered in the table (step S52: N), While registering, an expiration date is set (step S54). As the expiration date, for example, a predetermined time later can be considered.

  If registered (step S52: N), the expiration date is updated for a predetermined time (step S55). When the expiration date expires, the distribution source database 1 deletes the multicast address set.

(Example 8)
Next, an eighth embodiment of the present invention will be described with reference to the drawings.
FIG. 13 is a diagram illustrating an operation example of the eighth embodiment. The IP multicast address registration range is set in advance.

  In FIG. 13, when the distribution source database 1 receives the multicast address set notification from the distribution server accommodating router 2 (step S61), it confirms whether the IP multicast address of the multicast address set is within the set range (step S62). If it is within the range (step S62: Y), the operation of the seventh embodiment is performed (step S63).

Example 9
Next, Embodiment 9 of the present invention will be described with reference to the drawings.
FIG. 14 is a diagram illustrating an operation example of the ninth embodiment. The registration range of the distribution source IP address is set in advance.

  In FIG. 14, when the distribution source database 1 receives the multicast address set notification from the distribution server accommodating router 2 (step S71), it confirms whether or not the distribution source IP address of the multicast address set is within the set range (step S71). If it is within the range (step S72: Y), the operation of the seventh embodiment or the eighth embodiment is performed (step S73).

(Example 10)
Next, a tenth embodiment of the present invention will be described with reference to the drawings.
FIG. 15 is a diagram illustrating an operation example of the tenth embodiment. The IP address registration range of the distribution server accommodating router is set in advance.

  In FIG. 15, when the distribution source database 1 receives the multicast address set notification from the distribution server accommodating router 2 (step S81), it confirms whether the transmission source IP address of the packet is within the set range (step S82). If it is within the range (step S82: Y), the operation of the seventh embodiment, the eighth embodiment or the ninth embodiment is performed (step S83).

  The processing performed by the distribution source database 1 and the host accommodating router 2 described above is program-coded and recorded on a computer-readable recording medium and distributed, or distributed to users via a network such as the Internet. It is possible.

It is a figure which shows the example of an IP network structure of Example 1 of this invention. It is a figure which shows the table structural example of the delivery origin database of Example 1 of this invention. It is a figure which shows the operation example 1 of Example 1 of this invention. It is a figure which shows the operation example 2 of Example 1 of this invention. It is a figure which shows the operation example of Example 2 of this invention. It is a figure which shows the example of a table structure of the delivery server accommodation router of Example 3 of this invention. It is a figure which shows the operation example of Example 3 of this invention. It is a figure which shows the operation example of Example 4 of this invention. It is a figure which shows the operation example of Example 5 of this invention. It is a figure which shows the operation example of Example 6 of this invention. It is a figure which shows the example of a table structure of the delivery origin database of Example 7 of this invention. It is a figure which shows the operation example of Example 7 of this invention. It is a figure which shows the operation example of Example 8 of this invention. It is a figure which shows the operation example of Example 9 of this invention. It is a figure which shows the operation example of Example 10 of this invention.

Explanation of symbols

1: Distribution source database 11: Table configuration example 2: Distribution server accommodating router 21: Table configuration example 3: Distribution server 4: Host accommodating router 5: Host 6: Multicast relay router 11, 21: Table configuration example

Claims (12)

An IP multicast routing system in an IP multicast network comprising at least a host, a host accommodating router, a distribution server, and a distribution server accommodating router,
A distribution source database for storing a combination of an IP multicast address and an IP address of the multicast distribution server (hereinafter referred to as a multicast address set);
When the distribution server accommodating router receives a multicast packet from the distribution server, the distribution server accommodating router notifies the distribution source database of a combination of a destination IP address and a transmission source IP address described in the multicast packet as a multicast address set;
The distribution source database registers the multicast address set when the multicast address set is notified, and is specified when the multicast address set request specifying the IP multicast address is received from the host or the host accommodating router. An IP multicast route control system that notifies all the multicast address sets corresponding to the IP multicast address to the host or the host accommodating router. The IP multicast routing system according to claim 1, wherein
The distribution source database includes means for storing a reception state for each registered multicast address set, and among the registered multicast address sets, a multicast address set for which there is no notification during reception within a predetermined time period. With a means to delete,
The distribution server accommodating router is provided with means for monitoring a reception state of a multicast packet and periodically notifying a distribution source database of a multicast address set of the multicast packet being received. The IP multicast routing system according to claim 2, wherein
The means for monitoring the reception state of the multicast packet and periodically notifying the multicast address set of the multicast packet being received includes a table for storing the multicast address set and a reception flag, and a timer for measuring a predetermined period. Prepared,
The distribution server accommodating router acquires the IP header information of the multicast packet received between the timer activation and the timeout, and if the multicast address set of the received multicast packet exists in the table, the reception flag is being received. If it does not exist, register the multicast address set in the table and receive the reception flag. If the timer times out, delete the multicast address set for which the reception flag has not been received and receive the reception flag. An IP multicast route control system, wherein after the multicast address set is notified to the distribution source database, the reception flag is changed to unreceived. The IP multicast routing system according to claim 2, wherein
The means for monitoring the reception status of the multicast packet of the distribution server accommodating router and periodically notifying the multicast address set of the multicast packet being received includes a packet number counter, and counts the received data packet by the packet number counter. An IP multicast routing system characterized in that information on a destination IP address and a source IP address is periodically acquired, and if the destination address is an IP multicast address, the information is notified to a distribution source database. In the IP multicast routing system according to claim 3 or 4,
The means for monitoring the reception state of the multicast packet and periodically notifying the multicast address set of the multicast packet being received comprises means for storing the IP multicast address range to be notified, and the destination IP address of the acquired data packet Alternatively, when the IP multicast address of the multicast address set registered in the table is an IP multicast address in a stored range, the IP multicast route control system is notified to the distribution source database. The IP multicast routing system according to claim 5, wherein
The means for monitoring the reception state of the multicast packet and periodically notifying the multicast address set of the multicast packet being received comprises means for storing a range of distribution source IP addresses to be notified, and the destination IP of the acquired data packet An IP multicast route control system that notifies a distribution source database when an address or an IP multicast address of a multicast address set registered in a table is a distribution source IP address in a stored range. In the IP multicast routing system according to any one of claims 2 to 6,
The means for storing the reception state for each registered multicast address set includes a table for storing the multicast address set and the expiration date,
When the multicast address set is notified from the distribution server accommodating router within the stored expiration date, the distribution source database updates the expiration date for the notified multicast address set, or the expiration date is An IP multicast routing system characterized by deleting an expired multicast address set. The IP multicast routing system according to claim 7,
The means for storing the reception state for each registered multicast address set includes means for storing a range of IP multicast addresses to be registered. When the distribution source database registers a multicast address set, the IP multicast address is The IP multicast routing system, wherein the multicast address set is registered only when it is within the stored range. The IP multicast routing system according to claim 7 or 8,
The means for storing the reception state for each registered multicast address set includes means for storing a range of distribution source IP addresses to be registered, and the distribution source database has a distribution source IP address when registering a multicast address set. The IP multicast routing system, wherein the multicast address set is registered only when the address is within the stored range.   The distribution source database according to any one of claims 1 to 9 includes means for storing an IP address of a distribution server accommodating router that accepts a multicast address set, and the distribution source database has received a multicast address set notification. In this case, the source IP address of the notification packet is confirmed, and if the IP address of the stored distribution server accommodating router is accepted, the notification is discarded if the IP address is not stored. Multicast routing system. An IP comprising at least a host, a host accommodating router, a distribution server, a distribution server accommodating router, and a distribution source database that stores a combination of an IP multicast address and an IP address of the multicast distribution server (multicast address set) An IP multicast routing method in a multicast network,
When the distribution server accommodating router receives a multicast packet from the distribution server, notifying the distribution source database of a combination of a destination IP address and a transmission source IP address described in the multicast packet as a multicast address set;
The distribution source database registers the multicast address set when notified of the multicast address set, and is specified when the multicast address set request specifying the IP multicast address is received from the host or the host accommodating router. A method of notifying the host or the host accommodating router of all the multicast address sets corresponding to the IP multicast address. The IP multicast route control method according to claim 11, wherein
The distribution source database stores a reception state for each registered multicast address set;
The distribution server accommodating router monitors the reception state of the multicast packet and periodically notifies the distribution source database of the multicast address set of the multicast packet being received;
The IP multicast route control method, wherein the distribution source database includes a step of deleting a multicast address set for which no notification of reception is received within a predetermined time period from registered multicast address sets.

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