JP4361446B2 - Multicast control method, multicast area management device, multicast control device, and program - Google Patents

Description

  The present invention relates to a multicast distribution technique, and more particularly, to a multicast distribution technique that enables continuous reception of content even when a mobile IP client that is receiving multicast content by wireless access moves from the receiving area to another area. .

  FIG. 1 shows a multicast distribution system using the prior art. The multicast distribution system shown in FIG. 1 includes a content distribution server that distributes content, a multicast-compatible router, and a client that receives the multicast-distributed content. In the example of FIG. 1, each client can communicate with the Internet via a wireless access point. The wireless access point is connected to the multicast-compatible routers 1 and 3 via the layer 2 switch.

  Each client has a function related to multicast such as IGMP. In order for clients under the multicast-capable routers 1 and 3 to receive multicast distribution of content corresponding to a specific multicast address, first, one of the clients (for example, the client 5) distributes including the multicast address to the content distribution server. Send a request. The content distribution server that has received the distribution request transmits the content, the content is transmitted to the multicast-compatible router 1, and the multicast-compatible router 1 multicasts the content to all the clients in the network area where the client 5 exists, Only clients participating in the multicast group corresponding to the content receive the content.

As a conventional technique related to multicast, there is a technique disclosed in Patent Document 1, for example. Further, there are Non-Patent Documents 1 to 3 as references related to multicast.
JP 2002-026903 A Internet STD5, RFC1112 `` Internet Group Management Protocol (IGMP) '' IETF Network Working Group, August, 1989 Internet RFC2876 "Multicast Listener Discovery (MLD) for IPv6" IETF Network Working Group, October, 1999 Internet Draft "Explicit Multicast (Xcast) Basic Specification" R. Boivie (IBM) et al., January, 2003

  Now, even when the client moves across the network on the IP network, the mobile IP that automatically detects the movement between the networks and can continue the communication in the network after the movement as before the movement. There is technology. When this mobile IP is used, a location management device called a home agent (HA) is used as shown in FIG. In mobile IP technology, a home agent (HA) has a home address (HoA) unique to the client that does not change wherever the client is, and a care-of address (CoA, care of address) that changes for each network in which the client exists. The above functions are realized by managing them as binding information in association with each other.

  By using the mobile IP technology, it is possible to support the movement of a client between networks in content distribution by unicast only by transmitting data to a specific address. However, because the multicast distribution technology distributes the content corresponding to the multicast address requested for distribution to the area (network) where the distribution request is issued, the area where the client exists has changed. In this case, the content cannot be received unless a new distribution request is made. The current mobile IP technology cannot cope with the movement of the client between areas in such multicast distribution.

  The present invention has been made in view of the above points, and even when a mobile IP client receiving multicast content moves from the receiving area, multicasting is performed in the destination area without re-requesting the multicast content. An object of the present invention is to provide a technology that enables continuous reception of content.

  The above problem is that a content distribution device as a content transmission source, at least one multicast control device having a function of multicast distribution of content to clients, a home agent device in mobile IP, and a multicast area management device are connected to a communication network. A multicast control method in a multicast distribution system configured to be connected to the network, wherein the multicast control device under the first area includes: client identification information, content identification information, and client identification information from a client existing in the first area; When the multicast distribution to the first area is performed based on the content distribution request, the multicast area management device receives the content identification information and the first The multicast area management device that has transmitted the information including rear identification information and the client identification information and received the information retains the information, and the home agent device has the second area identification information and the information When information including information for identifying a client is received from the client, information including identification information for the second area and information for identifying the client is transmitted to the multicast area management device, and the multicast area management device Detects the movement of the client from the held information and the information received from the home agent device, and sends the content identification information and the second information to the multicast control device under the second area. The information including the identification information of the area is transmitted and the information is received Multicast controller, can be solved by the multicast control method characterized by initiating a multicast delivery of the content to the second area.

  In the multicast control method, the multicast distribution system further includes a content attribute information management device, and the content attribute information management device associates at least content identification information and content distributable area information for each content. The multicast control device, before starting multicast distribution of content, the content identification information of the content and the identification information of the target area to distribute the content to the content attribute information management device, Is transmitted to the content attribute information management device, and the multicast control device receives the message indicating that the content can be distributed to the target area from the content attribute information management device. Eli You may start the multicast distribution of content to.

  The multicast area management device receives content identification information of the content, identification information of the first area, and information of the client from a multicast control device that multicasts content to the first area based on a content distribution request from a client. Means for receiving information including client identification information and retaining the information; and from the home agent device that has received binding information from the client that has moved to a second area; Multicast control for detecting the movement of the client from the means for receiving information including information for identifying the client, the held information, and the information received from the home agent device, and controlling the second area For the device, the controller Constructed and means for transmitting information including Ntsu identification information and the identification information of the second area.

  The multicast control apparatus receives a content distribution request including client identification information and content identification information from a client in a certain area, and performs multicast distribution to the area based on the content distribution request. Detecting a movement of the client using means for transmitting information including the content identification information, the area identification information, and the client identification information to the multicast area management device, and information received from the home agent device. Information including content identification information and identification information of other areas is received from the multicast area management apparatus, and the content identification information corresponds to the other areas corresponding to the received identification information of the other areas. Multicast content Constructed and means for signal.

  According to the present invention, the multicast control apparatus notifies the multicast area management apparatus of the client area information and the received content information, and the multicast control apparatus receives information related to the movement of the client between the areas from the home agent apparatus. Therefore, when the client moves between areas, the multicast area management device can transmit information on the moved area and the received content to the multicast control device corresponding to the moved area, and the multicast control corresponding to the moved area. The apparatus can distribute the content received by the client in the area before the movement to the client after the movement. Therefore, even when a client receiving content moves from the receiving area, the content can be continuously received in the destination area without re-requesting the content.

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

  A multicast distribution system according to an embodiment of the present invention is shown in FIG. As shown in FIG. 2, this multicast distribution system includes a content distribution server (CDS), an address mapping server (AMS), a multicast control gateway (MCG: Multicast Gateway Server), a splitter (SP: Splitter), home agent (defined in HA: Home Agent, draft-ietf-mobileip-ipv6), and home agent control server (HACS) are connected to the IP network. ing. A wireless access point (AP) is connected to the multicast control gateway (MCG) via a layer 2 switch, and a client exists under the wireless access point (AP).

  The content distribution server (CDS) is a server that uses this system to stream content, and each client is a user terminal that uses the stream-distributed content. The client connects to the multicast control gateway (MCG) via the wireless access point (AP) and receives the multicast content from the multicast control gateway (MCG). Hereinafter, the function of each device constituting the multicast distribution system of the present embodiment will be described.

  For each content, the address mapping server (AMS) has a multicast address corresponding to the content (sometimes referred to as a multicast channel or a multicast group) and an attribute of the content (address of the content distribution source server, content Holdable area, stream bandwidth, encryption method, etc.). For example, the content provider sets the values of these attributes.

  The “area” in the present embodiment is a network area identified by the network part of the IP address, but is not limited to this, and various definitions are possible. By associating network areas with “hotels”, “restaurants”, “schools”, etc., these can also be used as “areas”. “Multicast” in the present embodiment is an IP multicast defined in IETF RFC1112, RFC2710, or the like, but the multicast to which the present invention is applied is not limited to this.

  The multicast control gateway (MCG) receives the content distribution request from the client, acquires the content attribute from the address mapping server (AMS), and if it can be distributed to the area where the content request source client exists, the splitter (SP) and a content distribution server (CDS) are requested to create a content distribution tree and distribute the content. Thereafter, the content distributed along the content distribution tree is multicast distributed to the content requesting client. Also, the MCG can control whether multicast distribution is possible in VLAN units (VLAN network address units). In addition, client identification information and area information associated with binding information exchanged between the home agent (HA) and the mobile IP client is acquired from a home agent management server (HACS), and the connection destination area of the client is acquired. And the like.

  The splitter (SP) forms a distribution tree for efficiently distributing content from the content distribution server (CDS) to each MCG, and the content is transmitted from the content distribution server (CDS) to each multicast control gateway (MCG). Branch delivery by relaying the stream.

  The home agent management server (HACS) acquires the mobile IP client home address and existing area information from the home agent (HA) function for managing the multicast reception status of the mobile IP client and the network of the mobile IP client. Detect position.

  In the example shown in FIG. 2, a VLAN (virtual LAN) is constructed by using a layer 2 switch under each multicast control gateway (MCG), and one area formed by the VLAN becomes one wireless access point (AP). It is associated. The location (address and communication port) of the address mapping server (AMS) is preset in the multicast control gateway (MCG), and direct communication is possible between the address mapping server (AMS) and each multicast control gateway (MCG). .

  The multicast control gateway (MCG) is configured to be able to use IP multicast, but in the wide area network upstream from the multicast control gateway (MCG), only unicast distribution is possible. That is, in content stream transfer from the content distribution server (CDS) to each multicast control gateway (MCG), IP multicast packets are encapsulated into unicast packets and distributed. The outline of the operation of the system configured as described above is as follows.

  When a client sends a content distribution request to the multicast control gateway (MCG), the multicast control gateway (MCG) performs address mapping between the area identification information to which the client belongs and the requested content identification information (multicast address). The AMS determines whether the content can be received in the area from the received information, and if possible, sends information including the address of the content distribution server (CDS) to the multicast control gateway (AMS). The MCG transmits a content distribution request to the content distribution server (CDS) at the address via the splitter (SP). The content distribution server (CDS) that has received the distribution request transmits the requested content. The content is transferred to a multicast control gateway (MCG) as a request transmission source along a route through which the distribution request has passed, and is multicast distributed from the MCG to clients in the area related to the request.

  For the mobile IP client, the home agent (HA) receives binding information (including client identification information (home address) and area information) from the client, and the home agent (HA) manages the information. By transmitting to the server (HACS), the home agent management server (HACS) manages the existence area of the client. The multicast control gateway (MCG) notifies the home agent management server (HACS) of content identification information received by the client when performing content distribution based on the content distribution request from the mobile IP client. The agent management server (HACS) manages the information. When the mobile IP client moves to another area, the home agent management server (HACS) detects the movement of the client by receiving the area information after movement from the home agent (HA), and the area after movement. Information or the like is notified to the multicast control gateway (MCG) corresponding to the area, and the multicast control gateway (MCG) starts multicast distribution of the content in the area after the client moves.

  The multicast control gateway (MCG) is an example of a multicast control device in claims, and the address mapping server (AMS) is an example of a content attribute information management device in claims, and a content distribution server (CDS) Is an example of a content distribution apparatus in the claims. The home agent (HA) is an example of a home agent device in the claims, and the home agent management server (HACS) is an example of a multicast area management device in the claims.

  Next, the configuration of each device will be described. FIG. 3 is a functional block diagram of the multicast control gateway (MCG).

  The multicast control gateway (MCG) includes a stream distribution unit 11, a stream reception unit 12, a stream distribution request unit 13, a content attribute request unit 14, a content reception client detection unit 16, a HACS communication unit 17, and a control unit 15. Yes. The control unit 15 includes a session management unit 151, an area information management unit 152, a unicast / multicast conversion unit 153, and a mobile IP client information management unit 154.

  The content reception client detection unit 16 receives a content distribution request message for requesting multicast distribution of content from the client. This message is, for example, an IGMP Join message.

  The stream delivery unit 11 multicasts the requested content to the client. The stream distribution request unit 14 transmits a content distribution request message to the content distribution source server (CDS) or the splitter (SP). The stream receiving unit 12 receives content stream-distributed from a content distribution source server (CDS) or a splitter (SP). The content attribute request unit 13 transmits a message requesting content attributes to the address mapping server (AMS) and receives a response. Further, the HACS communication unit 17 receives the client identification information of the mobile IP client, the area information, and the receiving content identification information of the mobile IP client from the home agent management server (HACS). Further, it notifies the home agent management server (HACS) of the content identification information requested from the mobile IP client.

  The session management unit 151 of the control unit 15 manages a session with a client and a stream transmission / reception session with a content distribution server (CDS) or a splitter (SP). The area information management unit 152 of the control unit 15 has a function of managing area information for each VLAN under the gateway, and the unicast / multicast conversion unit 153 of the control unit 15 multicasts the content to the client group. Therefore, the unicast stream received from the content distribution source server (CDS) or the splitter (SP) is converted into a multicast stream. The mobile IP client information management unit 154 manages client identification information such as the IP address (including area information) and MAC address of the mobile IP client received by the HACS communication unit 17.

  FIG. 4 shows a functional block diagram of the splitter (SP). As shown in the figure, the splitter (SP) includes a content request receiving unit 21, a stream distribution unit 22, a stream distribution request unit 23, a stream reception unit 24, and a control unit 25. The control unit 25 includes a session management unit 251 and a multicast / unicast conversion unit 252.

  The content request reception unit 21 receives a content distribution request message from the downstream multicast control gateway (MCG) or splitter (SP), and the stream distribution unit 22 sends the content to the downstream multicast control gateway (MCG) or splitter (SP). On the other hand, it has a function of streaming the requested content. The stream distribution request unit 23 transmits a content distribution request message to the upstream splitter (SP) or content distribution server (CDS), and the stream reception unit 24 transmits the upstream splitter (SP) or content distribution server. (CDS) has a function of receiving content stream-distributed.

  The session management unit 251 of the control unit 25 manages the stream transmission / reception session with the downstream splitter (SP), the multicast control gateway (MCG), and the upstream splitter (SP) and the content distribution server (CDS). The unicast conversion unit 252 has a function of converting an IP multicast packet received from the content distribution server (CDS) into a unicast packet in order to transfer the IP multicast packet through the unicast network.

  FIG. 5 shows a functional block diagram of the address mapping server (AMS). As shown in the figure, the address mapping server (AMS) includes a content attribute request receiving unit 31, a content attribute transmitting unit 32, a content attribute management database 33, an attribute operation user interface unit 34, and a control unit 35. The control unit 35 includes a database access unit 351 and a content distribution availability control unit 352.

  The content attribute request receiving unit 31 receives a content attribute request message from the multicast control gateway (MCG). The content attribute transmission unit 32 transmits a response message to the content attribute request to the content attribute request source MCG. For an MCG in a distributable area, a content attribute is included as a response message. The content attribute management database 33 manages attribute information in which a multicast address, a distribution source server address, distributable area information, and the like are associated with each content. The attribute operation user interface unit 34 displays a screen for operating content attributes, and receives an attribute operation input from the user.

  The database access unit 351 of the control unit 35 accesses the database 33 and reads / writes attribute values when a content attribute request is received from the multicast control gateway (MCG) and when an attribute operation is performed by the user. The content distribution availability control unit 352 collates the information in the database 33 with the area information of the content attribute request source, and determines whether to permit distribution of the requested content to the area based on the collation result.

  FIG. 6 shows a functional block diagram of the home agent management server (HACS). As shown in FIG. 6, the home agent management server (HACS) includes a home agent communication unit 41, a client movement information transmission unit 42, a client reception information reception unit 43, a client information database 44, and a control unit 45. Further, the control unit 45 has a database access unit 451.

  The home agent communication unit 41 receives the home address and area information of the mobile IP client authenticated by the home agent (HA) from the home agent (HA). The client movement information transmission unit 42 has a function of notifying the multicast control gateway (MCG) of the area where the mobile IP client exists, the MAC address of the client, the content identification information (multicast address) being received, and the area information. Have. The client reception information receiving unit 43 has a function of receiving content identification information (multicast address) being received by the mobile IP client from the multicast control gateway (MCG).

  The client information database 44 receives client identification information (MAC address and home address), client area information (network prefix), and client received from the multicast control gateway (MCG) or home agent (HA). The database access unit 451 of the control unit 45 updates the mobile IP client identification information, the existing network area, and the content identification information managed in the database. The client information database 44 is accessed for reference.

  The functional unit in each of the above devices is realized by causing a computer to execute a program describing the processing content described in the present embodiment. Each of the above devices can be realized by a computer having a communication processing function. The multicast control gateway (MCG) and the splitter (SP) can also be realized by a router.

(Basic processing contents of the multicast distribution system)
First, before describing the processing contents related to the movement of the mobile IP client between areas, the basic processing contents of the multicast distribution system as a premise thereof will be described with reference to FIGS.

  FIG. 7 is a diagram illustrating a sequence from a content distribution request by a client to a start of content multicast distribution.

  The processing sequence in the multicast distribution system according to the present embodiment can be broadly divided into a content distribution area check stage, a content distribution tree creation stage, and a content relay and multicast distribution stage. A sequence in each stage will be described with reference to FIG. FIG. 7 shows an example of passing through two splitters (SP1, SP2).

(1) Content Distribution Area Check Stage As described above, the multicast control gateway (MCG) manages area information (network prefix) related to the subordinate LAN (or VLAN). When a client in a subordinate area issues a distribution request for a certain content (step 1), the content reception client detection unit 16 of the multicast control gateway (MCG) receives this distribution request. This distribution request includes the content identification information (multicast address) and area information.

  Next, the multicast control gateway (MCG) sends a content attribute request message from the content attribute request unit 13 to the address mapping server (AMS) in order to request the attribute of the content requested to be distributed from the client (step S31). 2). In the multicast control gateway (MCG), the address and port number of the address mapping server (AMS) are set in advance in a configuration file or the like. The content attribute request message includes a multicast address and content distribution destination area information (network prefix, that is, a network address, etc.).

  When the content attribute request receiving unit 31 of the address mapping server (AMS) receives the content attribute request message, the content attribute request receiving unit 31 notifies the control unit 35 of the content of the message. The control unit 35 of the address mapping server (AMS) refers to the content attribute management database 33 of the address mapping server (AMS), determines the distributable area information for the requested content and the distribution destination area information included in the message. Collate. If the content distribution is possible to the area where the client exists as a result of this collation, the address mapping server (AMS) notifies the content attribute from the content attribute transmission unit 32 to the multicast control gateway (MCG). (Step 3). The content attribute includes an address of a content distribution source server (CDS) that distributes the content related to the request.

When the content attribute request unit 13 of the multicast control gateway (MCG) receives the content attribute, the content attribute request unit 13 notifies the control unit 15, and the control unit 15 manages a distribution destination area / multicast address pair as session information. Then, a content distribution request message is transmitted from the stream distribution request unit 14 to the address of the content distribution source server (CDS) (step 4). The content distribution request message includes the CDS address, the multicast address corresponding to the requested content, and the address of the request source MCG.
(2) Stage of Content Distribution Tree Creation In this embodiment, a splitter (SP) serving as a relay device exists in the communication path between the multicast control gateway (MCG) and the content distribution source server (CDS). In the example shown in FIG. 7, there are nodes serving as two splitters (SP) of SP1 and SP2, SP1 is close to MCG, and SP2 exists between SP1 and CDS. At this time, the content distribution request message transmitted from the multicast control gateway (MCG) to the content distribution server (CDS) is first received by the content request receiving unit 21 of the splitter (SP1). When receiving the content distribution request message, the content request receiving unit 21 of the splitter (SP1) notifies the control unit 25 of the message. The control unit 25 of the splitter (SP1) processes this request message as follows.

  (2.1.1) A pair of a source MCG address and requested content identification information (multicast address) is held in a storage device as session information (also referred to as a distribution destination table).

  (2.1.2) Subsequently, the request source address of the content distribution request message is changed to the address of itself (SP1) instead of the address of the source MCG. Then, the rewritten content distribution request message is transmitted from the stream distribution request unit 23 to the content distribution server (CDS) (step 5).

  This content distribution request message is set in advance so as to relay to the content distribution server (CDS) through the splitter (SP2). Therefore, this content distribution request message is received by the content request receiving unit 21 of the splitter (SP2). When receiving the content request message, the content request receiving unit 21 of the splitter (SP2) notifies the control unit 25 of the content request message. The control unit 25 of the splitter (SP2) processes this request message as follows.

  (2.2.1) A pair of the address of the transmission source SP1 and the identification information of the requested content is held in the storage device as session information.

  (2.2.2) Subsequently, the request source address of the content distribution request message is changed to the address of itself (SP2) instead of the address of the source SP1. Then, the rewritten content request message is transmitted to the content distribution server (CDS) (step 6).

In the present embodiment, this content distribution request message is not relayed by other SPs, but goes to the content distribution server (CDS), and the content distribution server (CDS) receives this distribution request message. The content distribution server (CDS) holds a pair of the address of the transmission source SP2 and the multicast address of the requested content as session information in the storage device.
(3) Stage of Content Relay and Multicast Distribution The content distribution server (CDS) distributes the requested content based on the held session information (step 7). In the above process, since SP2 is registered as the requested content distribution destination, the content is stream-distributed to the splitter (SP2) by unicast.

  The stream receiving unit 24 of SP2 distributes the content received from the content distribution server (CDS) based on the session information managed by the control unit 25. Since the session information for the splitter (SP1) is managed here, the stream is delivered from the stream delivery unit 22 to the splitter (SP1) (step 8).

  The stream receiving unit 24 of the splitter (SP1) distributes the content stream received from the splitter (SP2) based on the session information managed by the control unit 25. Here, since session information for the multicast control gateway (MCG) is managed, the stream is delivered from the stream delivery unit 22 to the multicast control gateway (MCG) (step 9).

  The stream receiving unit 12 of the multicast control gateway (MCG) distributes the content stream received from the splitter (SP1) based on the session information managed by the control unit 15. Here, since the session for the area where the client exists is managed, the content is multicast distributed from the stream distribution unit 11 to the area (step 10).

(Concrete example)
Next, the embodiment of the present invention will be described more specifically using the network configuration shown in FIG. FIG. 8 shows a configuration having two multicast control gateways (MCG1, MCG2) and two content distribution servers (CDS1, CDS2).

  In the multicast distribution system shown in FIG. 8, it is assumed that each device constituting the network communicates using IPv6 and is assigned an IPv6 address as shown in FIG.

  Two network areas, the area 1 corresponding to the prefix 2001: 0: 0: 1 :: / 64 and the area 2 corresponding to 2001: 0: 0: 2 :: / 64, as areas where the client can wirelessly access Exists. It is assumed that area 1 is under MCG1 and area 2 is under MCG2.

The access point side interface address of the multicast control gateway (MCG1) is 2001: 0: 0: 1 :: 2, and the unicast network side (Internet side) interface address is 2001: 0: 1: 1 :: 2. On the other hand, the multicast control gateway (MCG2) has an access point side interface address of 2001: 0: 0: 2 :: 2 and a unicast network side (Internet side) interface address of 2001: 0: 1: 2 :: 2. It is.
The address of the content distribution server (CDS1) of the two content distribution servers (CDS1, CDS2) is 2001: 0: 4: 1 :: 2, and the address of the content distribution server (CDS2) is 2001: 0: 5: 1 :: 2.

  The address mapping server (AMS) has an address of 2001: 9: 9: 9 :: 2, and the multicast control gateway (MCG1) and the multicast control gateway (MCG2) have an AMS of 2001: 9: 9: 9 :: 2 is read from the config file and recognized.

  The address mapping server (AMS) holds the content attribute information shown in FIG. 9 in the database. In the content attribute information, the content distribution server (CDS1) distributes two contents corresponding to the multicast addresses ff08 :: 1: 1 and ff08 :: 1: 2, and the contents of the multicast address ff08 :: 1: 1 are , The distribution of the prefix 2001: 0: 0: 1 :: / 64 is permitted only to the network area, and the content of the multicast address ff08 :: 1: 2 is the prefix 2001: 0: 0: 1 :: / 64. And the prefix 2001: 0: 0: 2 :: / 64, the distribution is permitted. Also, the content distribution server (CDS2) distributes the content of the multicast address ff08 :: 2: 1, and the content of the multicast address ff08 :: 2: 1 is only in the network of the prefix 2001: 0: 0: 2 :: / 64. It can be delivered to.

  Next, operations from the start of content request to the start of multicast distribution in the configuration of FIG. 8 will be described.

  First, the client 1 transmits a request message for requesting content corresponding to the multicast address ff08 :: 1: 1 (also referred to as a Join message, such as IGMP / MLD Report) to the multicast control gateway (MCG1).

  When the content reception client detection unit 16 of the multicast control gateway (MCG1) receives this request message, the multicast control gateway (MCG1) acquires an attribute of the requested multicast channel from the content requesting unit to obtain an address mapping server (AMS). ) A content attribute request message.

  FIG. 10 shows an example of the content attribute request message. As shown in FIG. 10, the content attribute request message includes the network prefix of the distribution destination (in this case, 2001: 0: 0: 1 :: / 64) and the multicast address. The content attribute request receiving unit 31 of the address mapping server (AMS) that has received this notifies the AMS control unit 35 of this. The control unit 35 refers to the content attribute information shown in FIG. 9 and determines whether or not the content of the requested multicast address can be distributed to the requesting network area 1.

  In the case of the present embodiment, as shown in FIG. 9, the content corresponding to the multicast address ff08 :: 1: 1 can be received in the network area of 2001: 0: 0: 1 :: / 64, and the content is the content. Since it is transmitted from the distribution server (CDS1), the content attribute transmission unit 32 of the address mapping server (AMS) transmits the content attribute having the contents shown in FIG. 11 to the multicast control gateway (MCG1). As shown in FIG. 11, the content attribute includes the requested multicast address and the address of the distribution source server that transmits the content corresponding to the multicast address.

  Subsequently, the stream distribution request unit 14 of the multicast control gateway (MCG1) uses the content attribute to send the multicast address (ff08) to the content distribution server (CDS1) (2001: 0: 4: 1 :: 2). :: 1: 1) A stream distribution request message for requesting a content stream is transmitted. FIG. 12 shows an example of the contents of the stream distribution request message. As shown in FIG. 12, the stream distribution request message includes the multicast address and the address of the distribution source server.

  A splitter (SP2) and a splitter (SP1) exist on the path between the multicast control gateway (MCG1) and the content distribution server (CDS1). First, the splitter (SP2) receives the stream distribution request message. Upon receiving this message, the splitter (SP2) holds session information having the multicast address and the address of the multicast control gateway (MCG1) of the request source in the control unit 25 of SP2, and heads upstream (CDS1). Then, a stream distribution request message with the request source address as the splitter (SP2) is transmitted.

  Further, since the splitter (SP1) exists in the path between the splitter (SP1) and the content distribution server (CDS1), the splitter (SP1) receives the message. The splitter (SP1) holds session information having the multicast address and the address of the request source splitter (SP2) in the control unit 25 of SP1, and sets the request source address to SP2 toward the upstream (CDS1). Send stream delivery request message. Upon receiving the stream distribution request message from the splitter (SP1), the content distribution server (CDS1) establishes a stream distribution session for SP1. Accordingly, the content distribution server (CDS1) to the splitter (SP1), the splitter (SP1) to the splitter (SP2), the splitter (SP2) to the multicast control gateway (MCG1), and the multicast control gateway (MCG1) to the client 1 The tree to be distributed is constructed. Note that “a tree has been constructed” refers to a state in which session information corresponding to specific content (multicast address) is held in each of the above nodes.

  Thereafter, the content corresponding to the multicast address (ff08 :: 1: 1) is transmitted from the content distribution server (CDS1) to the splitter (SP1). The splitter (SP1) refers to the session information and determines that the content is to be transmitted to the splitter (SP2) and transmits it to SP2. The splitter (SP2) also transmits the content to the multicast control gateway (MCG1) by referring to the session information held by the splitter (SP2), and the multicast control gateway (MCG1) multicasts the content to the clients in the area 1.

  On the other hand, the client 2 existing in the area 2 of the prefix 2001: 0: 0: 2 :: / 64 sends the content corresponding to the multicast address (ff08 :: 1: 1) to the multicast control gateway (MCG2). When requested, the content reception client detection unit 16 of the multicast control gateway (MCG2) receives a request message (IGMP / MLD Report) from this client. The multicast control gateway (MCG2) transmits a content attribute request message from the content attribute request unit 13 to the address mapping server (AMS) in order to acquire the attribute of the requested content. The content attribute request receiving unit 31 of the address mapping server (AMS) that has received this content attribute request message notifies this to the control unit 35 of the AMS. The control unit 35 refers to the content attribute information shown in FIG. 8 so that the content of the requested multicast address (ff08 :: 1: 1) is the request source prefix (2001: 0: 0: 2 :: / 64), it is determined that distribution is not possible, and the content attribute is not notified to the multicast control gateway (MCG2), but an error message is notified. As a result, a tree for distributing the content to the multicast control gateway (MCG2) is not constructed, and the client 2 is rejected to receive the requested content.

  Through the above procedure, the content stream distribution tree corresponding to the multicast address (ff08 :: 1: 1) is constructed as the path shown in FIG.

  In the configuration of FIG. 8, when both the client 1 and the client 2 request the content of the multicast address (ff08 :: 1: 2), according to the content attribute information of FIG. 9, the multicast address (ff08 :: 1: 2) Can be distributed from the content distribution server (CDS1) to both network areas, a stream distribution tree as shown in FIG. 14 is constructed. Further, when both the client 1 and the client 2 request the content of the multicast address (ff08 :: 2: 1), the content of the multicast address (ff08 :: 2: 1) is determined according to the content attribute information of FIG. Since the content distribution server (CDS2) can only distribute to area 2, the stream distribution tree shown in FIG. 15 is constructed.

(Processing content related to mobile IP client movement between areas)
Next, when the mobile IP client receiving the content moves from the receiving area to another area, the client location detection in the destination area and the client absence detection at the source are performed, and the content distribution tree An example of a sequence until the image is reconstructed will be described with reference to FIGS.

  In the following description, it is assumed that the client uses mobile IP and has received content distributed by IP multicast. The home agent management server (HACS) has a correspondence table of home addresses and MAC addresses, which are identification information of the clients. Note that the home address and the corresponding MAC address are input in advance. In addition, before the mobile IP client receives the content distribution, the multicast control gateway (MCG) having the client under its control receives the mobile agent from the home agent management server (HACS) that has received the binding information transfer from the home agent (HA). A MAC address is acquired and held as information for identifying an IP client. With this information, it can be identified that the client is a specific mobile IP client. The mobile IP client information may be information that can uniquely identify the client.

First, a processing sequence during movement across VLANs (VLAN1 and VLAN2) under the same multicast control gateway (MCG) will be described with reference to FIG. This sequence can be roughly divided into three stages: a client reception information management stage, a client movement detection stage, and a multicast distribution destination switching process stage. Hereinafter, processing in each stage will be described.
(1) Stage of Client Reception Information Management The multicast control gateway (MCG) receives a content distribution request from the mobile IP client, and starts content distribution through a sequence similar to the sequence shown in FIG. ) The HACS communication unit 17 of the multicast control gateway (MCG) notifies the home agent management server (HACS) of the content information (multicast address of the content) being received by the client (step 12). The home agent management server (HACS) retains the information associated with the identification information (MAC address and home address HoA) of the mobile IP client. The home agent management server (HACS) corresponds to the identification information (home address HoA) of the client in the information acquired from the home agent (HA) and the identification information (MAC address) of the client in the information acquired from the MCG. It has a table, and each information can be associated.
(2) Stage of client movement detection Next, it is assumed that the mobile IP client has moved under another area (VLAN 2). At this time, the mobile IP client notifies the updated binding information to the home agent (HA) from the destination area (step 13). Then, the home agent notifies this information to the home agent management server (HACS) (step 14). The information to be notified only needs to include area information and client identification information (home address).

The home agent communication unit 41 of the home agent management server (HACS) detects the movement of the client by receiving this information. Then, the client movement information transmission unit 42 of the home agent management server (HACS) notifies the absence of the client and the multicast stop request message to the multicast control gateway (MCG) that manages the source VLAN 1 (step 15). . As a result, multicast distribution is stopped if there is no other client receiving the same content. Further, the client movement information transmission unit 42 of the home agent management server (HACS) is configured to use a multicast control gateway (MCG) that manages the destination VLAN 2 (here, the MCG before and after the movement is the same, so the same MCG as described above). Is notified of a multicast distribution request message (movement information message) including area information in which the client exists, content identification information being received, and client identification information (MAC address) (step 16).
(3) Stage of Multicast Distribution Destination Switching Process When the HACS communication unit 17 of the multicast control gateway (MCG) receives the message, it notifies the control unit 15 and updates the session information. That is, the distribution destination area is the area after movement. Based on this updated session information, the stream distribution unit 11 of the multicast control gateway (MCG) starts multicast distribution in the destination VLAN 2 (step 17). Before starting content distribution to VLAN 2, the address mapping server (AMS) is inquired whether content distribution in that area is possible, and content distribution to VLAN 2 is started only when it is possible. It may be.

Next, a processing sequence at the time of movement between different multicast control gateways (MCG1, MCG2) will be described with reference to FIG. This sequence can also be roughly divided into three stages: a client reception information management stage, a client movement detection stage, and a multicast distribution destination switching process stage. Hereinafter, processing in each stage will be described.
(1) Stage of client reception information management The multicast control gateway (MCG1) receives a content distribution request from the mobile IP client, and starts content distribution through a sequence similar to the sequence shown in FIG. 7 (step 21). ) The HACS communication unit 17 of the multicast control gateway (MCG1) notifies the home agent management server (HACS) of the content information (multicast address of the content) being received by the client (step 22). The home agent management server (HACS) retains the information associated with the identification information (MAC address and home address HoA) of the mobile IP client. The home agent management server (HACS) corresponds to the identification information (home address HoA) of the client in the information acquired from the home agent (HA) and the identification information (MAC address) of the client in the information acquired from the MCG. It has a table, and each information can be associated.
(2) Stage of client movement detection Next, it is assumed that the mobile IP client has moved under another area (MCG2). At this time, the mobile IP client notifies the updated binding information to the home agent (HA) from the destination area (step 23). Then, the home agent notifies this information to the home agent management server (HACS) (step 24). The information to be notified only needs to include area information and client identification information (home address).

The home agent communication unit 41 of the home agent management server (HACS) detects the movement of the client by receiving this information. Then, the client movement information transmitting unit 42 of the home agent management server (HACS) notifies the absence of the client and the multicast stop request message to the multicast control gateway (MCG1) that manages the movement-source VLAN 1 (step 25). . Thereby, multicast distribution is stopped as described later. In addition, the client movement information transmission unit 42 of the home agent management server (HACS) sends, to the multicast control gateway (MCG2) that manages the destination VLAN 2, area information where the client exists, a multicast address being received, and client identification. A multicast distribution request message (movement information message) including information (MAC address) is notified (step 26).
(3) Stage of multicast distribution destination switching processing When the HACS communication unit 17 of the multicast control gateway (MCG1) receives the multicast stop request message, it notifies the control unit 15 and further from the control unit 15 to the stream distribution unit 11, If there is no other client receiving the same content, the stream distribution unit 11 stops the multicast content distribution. On the other hand, when receiving the movement information message, the HACS communication unit 17 of the multicast control gateway (MCG2) notifies the control unit 15 of the MCG2 and further from the control unit 15 to the content distribution unit 11, and the stream distribution unit 11 of the MCG2 Then, distribution of the multicast is started (step 27). Note that the sequence shown in FIG. 7 is executed when content distribution is started in the multicast control gateway (MCG2). Alternatively, if MCG1 and MCG2 are accommodated in the same splitter and the content distribution path from the splitter to the content distribution server (CDS) is the same, the session information of the splitter accommodating MCG1 and MCG2 is updated, and MCG1 and MCG2 The content may be distributed to the VLAN 2 via the MCG 2 from the splitter that accommodates.

(Specific example 1)
Next, a specific example of processing when a client moves between VLANs under the same multicast control gateway (MCG) will be described using the network configuration shown in FIG. Also in this network, it is assumed that each device communicates using IPv6 and is assigned an IPv6 address as shown in FIG.

  As shown in FIG. 18, there are two VLANs (VLAN1 and VLAN2) under the multicast control gateway (MCG3), and their network prefixes are 2001: 0: 0: 1 :: / 64 and 2001: 0: 0: 2 :: / 64. The content distribution server (CDS) whose address is 2001: 0: 4: 1 :: 2 distributes content corresponding to the multicast address ff08 :: 4: 4.

  The address mapping server (AMS) manages the content attribute information shown in FIG. This content attribute information indicates that the content distribution server (CDS) can distribute the content corresponding to the multicast address ff08 :: 4: 4 to both VLAN1 and VLAN2.

  As shown in FIG. 18, only the mobile IP client B exists as a client that receives the content, and this client B connects to the multicast control gateway (MCG3) and the Internet using mobile IPv6.

  In FIG. 18, the client B existing under the VLAN 1 first performs client authentication with respect to the home agent (HA). At this time, the client B transmits binding information to the home agent (HA). The binding information to be transmitted includes the home address (HoA) and care-of address (CoA) of client B. Part of the care-of address is area information (network prefix).

  The home agent (HA) notifies the home address and area information of the client B to the home agent management server (HACS). The binding information itself need not be notified. Thus, the home agent management server (HACS) recognizes that the client B exists under the area (VLAN1) represented by the prefix 2001: 0: 0: 1 :: / 64. Then, the home address of the client B is converted into the MAC address of the client B, and mobile IP client information including the MAC address of the client is notified to the multicast control gateway (MCG3) that manages the VLAN1. When the HACS communication unit 17 of the multicast control gateway (MCG3) receives the mobile IP client information, it notifies the control unit 15 and the control unit 15 manages the mobile IP client information. That is, the MAC address is stored in the storage device as that of the mobile IP client. It is assumed that the home agent management server (HACS) holds correspondence information between area information and MCG in advance.

  Subsequently, the mobile IP client B transmits a content distribution request message including information shown in FIG. 20 to the multicast control gateway (MCG3) in order to request the content of the multicast address ff08 :: 4: 4 in the VLAN1. As shown in FIG. 20, the content distribution request message includes the MAC address of the mobile IP client B and the multicast address ff08 :: 4: 4 of the content requesting distribution. In this example, a MAC address is used as identification information for uniquely identifying the mobile IP client B. The message also includes area information.

  The content reception client detection unit 16 of the multicast control gateway (MCG3) receives the content distribution request message, and acquires the source MAC address from this message (from the header portion of the message).

  The multicast control gateway (MCG3) compares this MAC address with the mobile IP client information managed by the control unit 15, and recognizes that the content distribution request message is a distribution request from the mobile IP client B. To do. Similarly to the procedure described with reference to FIG. 7 and the like, the multicast control gateway (MCG3) requests content attributes from the address mapping server (AMS).

  Since the content of multicast address ff08 :: 4: 4 can be distributed in the area based on the content attribute information shown in FIG. 19, the multicast control gateway (MCG3) makes a distribution request to the content distribution server (CDS). . Further, the multicast control gateway (MCG3) distributes the reception information message shown in FIG. 21 from the HACS communication unit 17 to the home agent management server (HACS), and the client B receives the content of ff08 :: 4: 4. Notify that. As shown in FIG. 21, the reception information message includes the MAC address of the mobile IP client B, the multicast address of the content being received by the mobile IP client B, and the area information (network prefix) where the mobile IP client B exists. Including. The home agent management server (HACS) holds this information as receiving information of the mobile IP client B.

  Next, it is assumed that the mobile IP client B moves from the bottom of VLAN 1 to the bottom of VLAN 2. The mobile IP client B transmits binding information to the home agent (HA) when it moves to the VLAN 2. Then, the home address of client B and area information (network prefix) are notified from the home agent (HA) to the home agent management server (HACS). Since the home agent management server (HACS) holds the home address and the network prefix before movement, the client B moves from VLAN 1 to VLAN 2 from the held information and the information received from the home agent. Detects movement.

  The home agent management server (HACS) notifies the multicast control gateway (MCG3) that manages the movement source VLAN 1 of the withdrawal of the receiving client B of the content of ff08 :: 4: 4 in VLAN1. Further, the home agent management server (HACS) transmits a movement information message shown in FIG. 22 to the multicast control gateway (MCG3) that also manages the VLAN2 that is the movement destination. This movement information message includes the MAC address of mobile IP client B, the multicast address of the content received by mobile IP client B, and the network prefix of the movement destination. The HACS communication unit 17 of the multicast control gateway (MCG3) receives this message and detects that the mobile IP client B has moved under the VLAN2.

  Subsequently, the content attribute request unit 13 of the multicast control gateway (MCG3) distributes the content of the multicast address ff08 :: 4: 4 in the movement destination network area (prefix 2001: 0: 0: 2 :: / 64). Therefore, a content attribute request message is transmitted to the address mapping server (AMS). As shown in FIG. 19, since content distribution is possible even in the destination area, the content attribute is returned from the address mapping server (AMS) to the multicast control gateway (MCG3), and the multicast control gateway (MCG3) moves. Recognize that it can be delivered to the destination area. The control unit 15 of the multicast control gateway (MCG3) updates the session information regarding the content distribution destination VLAN of ff08 :: 4: 4, and the stream distribution unit 11 of the multicast control gateway (MCG3) updates the multicast address ff08 :: in VLAN1. The 4: 4 content distribution is stopped and the multicast address ff08 :: 4: 4 content distribution in VLAN 2 is started. If there is a client that is receiving the content other than the mobile IP client B in the VLAN 1, the content distribution of the multicast address ff08 :: 4: 4 in the VLAN 1 is not stopped.

(Specific example 2)
Next, a specific example of processing when a client moves between different multicast control gateways (MCG4, MCG5) will be described using the network configuration shown in FIG. In this network, it is assumed that each device communicates using IPv6 and is given an IPv6 address as shown in the figure.

  As shown in FIG. 23, there are two multicast control gateways MCG4 and MCG5, and the network prefixes of the radio access areas under the control gateway are 2001: 0: 0: 1 :: / 64 and 2001: 0: 0: 2 :: / 64. Both areas are adjacent to each other in position. The content distribution server (CDS) whose address is 2001: 0: 5: 1 :: 2 distributes content corresponding to the multicast address ff08 :: 5: 5.

  The address mapping server (AMS) manages the content attribute information shown in FIG. This content attribute information indicates that the content distribution server (CDS) can distribute the content corresponding to the multicast address ff08 :: 5: 5 to both the area under MCG4 and the area under MCG5.

  As shown in FIG. 23, only the mobile IP client C exists as a client that receives the content, and the client C connects to the multicast control gateway and the Internet using mobile IPv6.

  Similarly to the example shown in FIG. 18, the client C existing under the MCG 4 first performs client authentication with respect to the home agent (HA). At this time, the client C transmits binding information to the home agent (HA). The binding information includes the home address (HoA) and care-of address (CoA) of client C. Part of the care-of address is area information (network prefix). The home agent (HA) notifies the home address and area information of the client C to the home agent management server (HACS). The home agent communication unit 41 of the home agent management server (HACS) holds this information. Accordingly, it can be recognized that the client C exists under the area (MCG4) represented by the prefix 2001: 0: 0: 1 :: / 64. Then, the home address of the client C is converted into the MAC address of the client, and mobile IP client information including the MAC address of the client is notified to the MCG 4. When receiving the mobile IP client information, the HACS communication unit 17 of the multicast control gateway (MCG4) notifies the control unit 15 of the MCG4, and the control unit 15 manages the mobile IP client information.

  Subsequently, since the mobile IP client C requests the content of the multicast address ff08 :: 5: 5 under the multicast control gateway (MCG4), the mobile IP client C sends a content distribution request message including the information shown in FIG. 25 to the multicast control gateway (MCG4). ). As shown in FIG. 25, the content distribution request message includes the MAC address of the mobile IP client C and the multicast address ff08 :: 5: 5 of the content requesting distribution.

  The content reception client detection unit 16 of the multicast control gateway (MCG4) receives the content distribution request message, and acquires the source MAC address from the header portion of the message.

  Then, the multicast control gateway (MCG4) compares this MAC address with the mobile IP client information managed in the control unit 15, and recognizes that the content distribution request message is a distribution request from the mobile IP client C. . In addition, the content attribute is requested to the address mapping server (AMS), and the content of ff08 :: 5: 5 can be distributed in the area, so the distribution request is made to the content distribution server (CDS), The multicast control gateway (MCG4) distributes the reception information message shown in FIG. 26 from the HACS communication unit 17 to the home agent management server (HACS), and the client C receives ff08 :: 5: 5 in the MCG4 area. To the home agent management server (HACS).

  Next, it is assumed that the mobile IP client C moves from under the multicast control gateway (MCG4) to under the multicast control gateway (MCG5). The client C transmits binding information to the home agent (HA) at the timing when it moves down to the multicast control gateway (MCG5). Then, the home address and area information (network prefix) of the client B are notified from the home agent (HA) to the home agent management server (HACS). As a result, the home agent management server (HACS) detects that the mobile IP client C has moved from below MCG 4 to below MCG 5.

  Then, the home agent management server (HACS) notifies the multicast control gateway (MCG4) that manages the movement source area that the client C that is receiving the content of ff08 :: 5: 5 has left. The HACS communication unit 17 of the multicast control gateway (MCG4) receives the message and detects that the client C does not exist under the multicast control gateway (MCG4). Further, the home agent management server (HACS) transmits the movement information message shown in FIG. 27 to the destination multicast control gateway (MCG5).

  The HACS communication unit 17 of the multicast control gateway (MCG5) receives the movement information message and detects that the client C exists under the multicast control gateway (MCG5). Note that the control unit 15 of the MCG 4 updates the session unless there is a client receiving content of ff08 :: 5: 5 other than the client C, and the stream distribution unit 11 of the MCG 4 stops the channel distribution. To do.

  Further, the content attribute request unit 13 of the multicast control gateway (MCG5) distributes the content of ff08 :: 5: 5 in the movement destination area (prefix 2001: 0: 0: 2 :: / 64), so that address mapping is performed. A content attribute request message is transmitted to the server (AMS). As shown in FIG. 24, since the stream distribution is possible in the destination area, the content attribute is returned from the address mapping server (AMS) to the multicast control gateway (MCG5), and the multicast control gateway (MCG5) Recognize that delivery is possible to the destination area. The control unit 15 of the multicast control gateway (MCG5) updates the session information regarding the channel ff08 :: 5: 5 (including the update of the session information of the upper splitter), and the stream distribution unit 11 of the multicast control gateway (MCG5) Stream distribution of the multicast address ff08 :: 5: 5 is started.

  In each of the above examples, when the home address and the client correspond one-to-one, the home address may be used instead of the MAC address as client identification information transmitted by the client. In this case, the correspondence table between the MAC address and the home address in HACS is not necessary.

  As described above, according to the multicast distribution system described in the present embodiment, the movement of the mobile IP client during the reception of the multicast content can be detected by the information received from the home agent (HA), and in synchronization with the movement detection. In the destination area, it is possible to multicast the content received by the client. Therefore, it is possible to provide a mobile environment for receiving a terminal while receiving multicast contents without executing a distribution request (multicast channel rejoin, etc.) again from an application that is using the multicast contents.

  The present invention is not limited to the above-described embodiments, and various modifications and applications can be made within the scope of the claims.

It is a figure which shows an example of the multicast delivery system in a prior art. It is a figure which shows the multicast delivery system in embodiment of this invention. It is a functional block diagram of a multicast control gateway. It is a functional block diagram of a splitter. It is a functional block diagram of an address mapping server. It is a functional block diagram of a home agent management server. It is a figure which shows the sequence from the delivery request of the content by a client to the multicast delivery start of a content. It is a figure for demonstrating operation | movement of the multicast delivery system in embodiment of this invention. It is an example of the content attribute information which an address mapping server hold | maintains. It is a figure which shows an example of the content of a content attribute request message. It is a figure which shows an example of the content of the content attribute message transmitted from an address mapping server. It is a figure which shows an example of the content of a stream delivery request message. It is a figure which shows the stream delivery tree of the content corresponding to a multicast address (ff08 :: 1: 1). It is a figure which shows the stream delivery tree of the content corresponding to a multicast address (ff08 :: 1: 2). It is a figure which shows the stream delivery tree of the content corresponding to a multicast address (ff08 :: 2: 1). It is a figure which shows an example of the sequence regarding the movement between areas of a mobile IP client (movement within the same multicast control gateway). It is a figure which shows an example of the sequence regarding the movement between areas of a mobile IP client (movement between different multicast control gateways). It is a figure for demonstrating operation | movement of the multicast delivery system in embodiment of this invention. It is a figure which shows the example of the content of content attribute information. It is a figure which shows the example of the content of a content delivery request message. It is a figure which shows the example of the content of a reception information message. It is a figure which shows the example of the content of a movement information message. It is a figure for demonstrating operation | movement of the multicast delivery system in embodiment of this invention. It is a figure which shows the example of the content of content attribute information. It is a figure which shows the example of the content of a content delivery request message. It is a figure which shows the example of the content of a reception information message. It is a figure which shows the example of the content of a movement information message.

Explanation of symbols

1, 3 Multicast router 5 Client AMS address mapping server CDS Content distribution server SP Splitter MCG Multicast control gateway HA Home agent HACS Home agent management server 11 Stream distribution unit 12 Stream reception unit 13 Stream distribution request unit 14 Content attribute request unit 15 Control Unit 16 content reception client detection unit 17 HACS communication unit 21 content request reception unit 22 stream distribution unit 23 stream distribution request unit 24 stream reception unit 25 control unit 31 content attribute request reception unit 32 content attribute transmission unit 33 content attribute management database 34 attribute Operation user interface unit 35 Control unit 41 Home agent communication unit 42 Client movement information transmission unit 3 client receiving information receiving unit 44 the client information database 45 control unit

Claims (6)

A content distribution device as a content transmission source, at least one multicast control device having a function of multicast distribution of content to clients, a home agent device in mobile IP, and a multicast area management device are connected to a communication network A multicast control method in a multicast distribution system, comprising:
The multicast control device under the first area receives a content distribution request including client identification information and content identification information from a client existing in the first area, and based on the content distribution request, When performing multicast distribution to one area, the information including the content identification information, the identification information of the first area, and the client identification information is transmitted to the multicast area management device,
The multicast area management device that has received the information holds the information,
When the home agent device receives information including identification information of a second area and information for identifying the client from the client, the home agent device includes information for identifying the second area and information for identifying the client. To the multicast area management device,
The multicast area management device detects the movement of the client from the held information and the information received from the home agent device, and provides the content identification to the multicast control device under the second area. Transmitting information including information and identification information of the second area;
The multicast control method that receives the information starts multicast distribution of the content to the second area. A content distribution device as a content transmission source, at least one multicast control device having a function of multicast distribution of content to clients, a home agent device in mobile IP, and a multicast area management device are connected to a communication network A multicast area management device used in a multicast distribution system,
Information including content identification information of the content, identification information of the first area, and client identification information of the client from a multicast control device that multicasts the content to the first area based on a content distribution request from the client Means for receiving and holding that information;
Means for receiving information including identification information of the second area and information for identifying the client from the home agent device that has received binding information from the client moved to a second area;
The content identification information and the second area are detected with respect to the multicast control device that detects the movement of the client from the held information and the information received from the home agent device and controls the second area. And a means for transmitting information including the identification information of the multicast area management apparatus. A content distribution device as a content transmission source, at least one multicast control device having a function of multicast distribution of content to clients, a home agent device in mobile IP, and a multicast area management device are connected to a communication network A multicast control device used in a multicast distribution system,
When receiving a content distribution request including client identification information and content identification information from a client existing in a certain area, and performing multicast distribution to the area based on the content distribution request, the multicast area management device, Means for transmitting information including content identification information, area identification information, and client identification information;
Information including content identification information and identification information of other areas is received from the multicast area management device that has detected the movement of the client using the information received from the home agent device, and the received identification of the other areas is received. Means for multicasting the content corresponding to the content identification information to the other area corresponding to the information. The multicast distribution system further includes a content attribute information management device, and the content attribute information management device holds a database for managing at least content identification information and content distributable area information in association with each content,
The multicast control device
Means for transmitting, to the content attribute information management device, content identification information of the content and identification information of a target area for distributing the content to the content attribute information management device before starting multicast distribution of the content;
4. A means for starting multicast distribution of the content to the target area when a message indicating that the content can be distributed to the target area is received from the content attribute information management apparatus. The multicast control device according to 1. A content distribution device as a content transmission source, at least one multicast control device having a function of multicast distribution of content to clients, a home agent device in mobile IP, and a multicast area management device are connected to a communication network A program for causing a computer to function as a multicast area management device used in a multicast distribution system, comprising:
Information including content identification information of the content, identification information of the first area, and client identification information of the client from a multicast control device that multicasts the content to the first area based on a content distribution request from the client Means to receive and retain that information,
Means for receiving information including identification information of the second area and information for identifying the client from the home agent device that has received binding information from the client moved to the second area;
The content identification information and the second area are detected with respect to the multicast control device that detects the movement of the client from the held information and the information received from the home agent device and controls the second area. Means for transmitting information including identification information of
Program to function as. A content distribution device as a content transmission source, at least one multicast control device having a function of multicast distribution of content to clients, a home agent device in mobile IP, and a multicast area management device are connected to a communication network A program for causing a computer to function as a multicast control device used in a multicast distribution system, comprising:
When receiving a content distribution request including client identification information and content identification information from a client existing in a certain area, and performing multicast distribution to the area based on the content distribution request, the multicast area management device, Means for transmitting information including content identification information, area identification information, and client identification information;
Information including content identification information and identification information of other areas is received from the multicast area management device that has detected the movement of the client using the information received from the home agent device, and the received identification of the other areas is received. Means for multicast distribution of the content corresponding to the content identification information to the other area corresponding to the information;
Program to function as.

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