JP4494279B2 - Multicast control method, multicast control device, content attribute information management device, and program - Google Patents

Description

  The present invention relates to a multicast distribution technique, and more particularly to a multicast distribution technique in which a content distribution source and a content distribution destination can be controlled.

  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 5 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 Internet RFC3547 “The Group Domain of Interpretation” M. Baugher (Cisco) et al., July, 2003 Internet RFC3775 “Mobility Support in IPv6” D. Johnson (Rice University) et al., June, 2004

  In the above prior art, to which network area multicast distribution is performed is determined by a request from a client, and control such as distribution of specific content only to a specific area cannot be performed on the network side.

  The present invention has been made in view of the above points, and the network side performs control such that a content distribution source server and a content distribution destination area are specified for each content, and content is multicast distributed only to the specified area. The purpose is to provide technology to do.

  The above-described problems are a multicast in a content distribution device that is a content transmission source, a multicast control device that has a function of multicast distribution of content to clients, and a multicast distribution system configured by connecting a content attribute information management device to a communication network. In the control method, the content attribute information management device holds a database for managing content identification information, a content distribution device address, and content distributable area information in association with each content, and the multicast control device includes: When a content distribution request including content distribution destination area information and content identification information is received from a subordinate client, a content including the content distribution destination area information and the content identification information is received. The content attribute information management apparatus that has transmitted the attribute request to the content attribute information management apparatus and received the content attribute request corresponds to the content distribution destination area information by referring to the database based on the content attribute request. It is determined whether or not the content corresponding to the content identification information can be distributed to an area to be transmitted, and if it is possible, information including the address of the content distribution device that is the transmission source of the content is transmitted to the multicast control device The multicast control device can solve the problem by a multicast control method, wherein the content distribution request is transmitted to the content distribution device that is the transmission source of the content, and the received content is multicast distributed to the area. .

  The multicast distribution system includes at least one relay device between the multicast control device and the content distribution device, and the relay device is transmitted from the multicast control device to the content distribution device. A relay device that receives a distribution request, holds the address of the relay device that is the transmission source immediately before the distribution request or the multicast control device and the content identification information as session information, and the relay device that is the next transmission destination Alternatively, when the content is transmitted to the content distribution apparatus and the content corresponding to the content identification information is received, the content may be transferred to an address included in the session information.

  The content distribution apparatus may have a mobile IP function, and the content attribute information management apparatus may hold a home address of the content distribution apparatus as an address of the content distribution apparatus.

  Further, the multicast distribution system includes a home agent of the content distribution device and a gateway device having the content distribution device under the control, and the home agent is based on an authentication request from the content distribution device. When the authentication is successful, the address information of the content distribution device is transmitted to the gateway device, the gateway device holds the address information of the content distribution device, and the received packet is transmitted from the content distribution device. It is determined based on the address information whether it is a sent packet or a packet addressed to the content distribution device, and if it is a packet sent from the content distribution device or a packet addressed to the content distribution device, the packet It can be configured to be transferred.

  Further, when the multicast control apparatus receives a content distribution request including content distribution destination area information and content identification information from a client under the control of the multicast control apparatus, the content distribution destination area information and the content identification information A content attribute request including the content identification request from the content attribute information management apparatus, and the content attribute information management apparatus determined to be able to distribute the content corresponding to the content identification information. Means for receiving information including an address of a content distribution device; means for transmitting a content distribution request to a content distribution device that is a transmission source of the content; and the received content corresponds to the content distribution destination area information Multicast in the area Configured to include a means to door delivery.

  In addition, when the content distribution device that is the transmission source of the content has a mobile IP function and the content attribute information management device holds the home address of the content distribution device as the address of the content distribution device, the content information The receiving means receives information including a home address of the content distribution device from the content attribute information management device.

  Further, in the case where the multicast distribution system includes a home agent of the content distribution device, and the multicast control device has the content distribution device under the control, the multicast control device receives from the home agent that has authenticated the content distribution device. Receiving the address information of the content distribution device, holding the address information, and determining whether the received packet is a packet transmitted from the content distribution device or a packet addressed to the content distribution device based on the address information. If the packet is transmitted from the content distribution apparatus or is destined for the content distribution apparatus, the packet may be transferred.

  In addition, the content attribute information management device includes a storage unit that holds a database for managing content identification information, a content distribution device address, and content distributable area information in association with each content, and the multicast control device. Means for receiving a content attribute request including content distribution destination area information and content identification information; and the content identification to an area corresponding to the content distribution destination area information by referring to the database based on the content attribute request A unit that determines whether or not distribution of content corresponding to the information is possible and, if possible, transmits information including an address of a content distribution device that is a transmission source of the content to the multicast control device. Is done.

  When the content distribution apparatus has a mobile IP function, the content attribute information management apparatus stores the home address of the content distribution apparatus in the database as the address of the content distribution apparatus.

  According to the present invention, the database of the content attribute information management apparatus holds the distributable area information for each content, and the content related to the request exists in the client by referring to the database according to the content distribution request from the client. In this case, it is determined whether or not distribution is possible, and if distribution is possible, distribution in that area is performed. Therefore, it is possible to perform control on the network side so that content is multicast distribution only to the specified area. Realized. Further, since the relay device records the session information and transfers the content based on the session information, the content can be flowed through a predetermined route.

  When the content distribution device has a mobile IP function, the content attribute information management device holds the home address of the content distribution device in the database as the content distribution device address, so the client is aware of the movement of the content distribution device. You can receive content without having to.

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

(First embodiment)
A multicast distribution system according to the first 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) is connected to the IP network. 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 distributes the requested content to the area where the content requesting client exists. If possible, it requests the splitter (SP) and content distribution server (CDS) to create a content distribution tree and distribute the content. Thereafter, the content distributed along the content distribution tree is multicast-distributed to the area of the content requesting client. Also, the MCG can control whether multicast distribution is possible in VLAN units (VLAN network address units).

  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.

  In the example shown in FIG. 2, under each multicast control gateway (MCG), a VLAN (virtual LAN) is constructed by using a layer 2 switch, and one area formed by the VLAN is one wireless access point (AP). Is associated with. 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.

  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.

  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 14, a content attribute request unit 13, a content reception client detection unit 16, and a control unit 15. The control unit 15 includes a session management unit 151, an area information management unit 152, and a unicast / multicast conversion unit 153.

  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.

  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.

  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. Information including the content attribute is transmitted as a response message to the MCG in the distributable area. 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.

  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.

  Next, the operation of the system of the present embodiment will be described with reference to the sequence diagram of FIG. FIG. 6 is a diagram illustrating a sequence from a content distribution request by a client to the 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. The sequence in each stage will be described with reference to FIG. FIG. 6 shows an example of passing through two splitters (SP1, SP2). In addition, content attribute information is registered in advance in the address mapping server.

(1) Content Distribution Area Check Stage As described above, the multicast control gateway (MCG) manages area information (network prefix) related to the subordinate LAN (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. 6, 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 distribution request message, the content request receiving unit 21 of the splitter (SP2) notifies the control unit 25 of the content distribution 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 distribution 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. 7 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. 7, it is assumed that each device constituting the network communicates using IPv6 and is given 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. 8 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. 7 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. 9 shows an example of the content attribute request message. As shown in FIG. 9, 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. 8 and determines whether or not the content of the requested multicast address can be distributed to the requesting network area 1.

  In this embodiment, as shown in FIG. 8, 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. 10 to the multicast control gateway (MCG1). As shown in FIG. 10, 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. 11 shows an example of the contents of the stream distribution request message. As shown in FIG. 11, the stream distribution request message includes a multicast address and an address of a 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 stream distribution tree of the content corresponding to the multicast address (ff08 :: 1: 1) is constructed as the path shown in FIG.

  In the configuration of FIG. 7, 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. 8, 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. 13 is constructed. Further, when both the client 1 and the client 2 request the content of the multicast address (ff08 :: 2: 1), according to the content attribute information of FIG. 8, the content of the multicast address (ff08 :: 2: 1) Since the distribution is possible only from the content distribution server (CDS2) to the area 2, the stream distribution tree shown in FIG. 14 is constructed.

  According to the multicast distribution system described in the present embodiment as described above, the content distribution source server and the content distribution destination area can be specified for each content by setting the database in the address mapping server. It is possible to reflect a policy in which content is multicast-distributed only to clients in the area on the network, and a content distribution tree can be dynamically constructed according to this policy.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. The second embodiment is an embodiment where the content distribution server has a mobile IPv6 node function and is movable.

  A system configuration in this embodiment is shown in FIG. As shown in FIG. 15, the system of this embodiment has a home agent (HA) in addition to a content distribution server (CDS), an address mapping server (AMS), a multicast control gateway (MCG), and a splitter (SP). is doing. Each multicast control gateway (MCG) is connected to a wireless access point (AP) via a layer 2 switch, and there are clients or content distribution servers (CDS) under the control.

  The home agent (HA) of the present embodiment is a device (for example, a router) having a mobile IPv6 home agent function (defined in draft-ietf-mobileip-ipv6), and has a home address and a care-of address. Manage in pairs. In addition, when the home agent (HA) of this embodiment authenticates the content distribution server (CDS) at the time of binding update or the like, the authentication result is sent to the multicast control gateway (MCG) under the content distribution server (CDS). ). Other basic functions of the apparatus are the same as those in the first embodiment. Further, in the present embodiment, content distribution from the content distribution server (CDS) is performed as unicast by encapsulating IP multicast packets into unicast packets.

  FIG. 16 shows a functional block diagram of a multicast control gateway (MCG) in the present embodiment. As shown in FIG. 16, the multicast control gateway (MCG) in this embodiment is different from the multicast control gateway (MCG) in the first embodiment (see FIG. 3) in the HA communication unit 41 and the authentication check unit 42. The packet filter unit 43 and the multicast restoration unit 44 are added.

  The HA communication unit 41 has a function of transmitting and receiving binding information between a home agent (HA) and a mobile IP client (content distribution server (CDS) in the present embodiment).

  The authentication check unit 42 has a function of checking whether or not the packet is information transmitted from an authenticated content distribution server (CDS) from the received header information of the IP packet. Further, when receiving an IP packet from the content distribution server (CDS), the packet filter unit 43 forwards the packet to the destination if it is transmitted from the authenticated content distribution server (CDS). Otherwise, it is discarded except for exceptions (binding information notification to the HA, etc.).

  The multicast restoration unit 44 has a function of restoring the unicast stream received from the CDS or SP to multicast in order to multicast the content to the client group.

  The management unit 15 of the present embodiment includes an authentication state management unit 155, a session management unit 151, and an area information management unit 152. The functions of the session management unit 151 and the area information management unit 152 are the same as those in the first embodiment. The authentication state management unit 155 manages the IP address (global address) of the authenticated content distribution server (CDS).

  FIG. 17 shows a functional block diagram of the splitter (SP). In the second embodiment, since the content distribution server (CDS) converts the multicast packet into unicast, the management unit 25 of the splitter (SP) uses the unicast / multicast conversion unit that existed in the first embodiment. 252 is not included. Other configurations are the same as those of the first embodiment. The configuration of the address mapping server (AMS) is the same as that in the first embodiment. However, the content attribute information stored in the address mapping server (AMS) is different from that of the first embodiment.

  Next, the operation of the system of this embodiment will be described with reference to the sequence diagram of FIG. This sequence authenticates a content distribution server (CDS), which is a mobile IP client, automatically generates a content multicast distribution tree for a client group requesting a multicast stream, and performs unicast encapsulation from the content distribution server (CDS). 2 is an example of a sequence from receiving a received multicast stream to starting multicast distribution of content.

  The processing sequence in the multicast distribution system according to the present embodiment includes (1) Multicast content registration to AMS, (2) Content distribution server authentication, (3) Content reception request processing, (4) Content distribution tree creation stage, And (5) Content relaying and multicast distribution can be roughly divided into five stages.

(1) Multicast content registration to AMS Register the content attribute information such as the multicast address and the unicast address of the content distribution server (CDS) (here, the mobile IPv6 home address) in advance in the address mapping server (AMS). Keep it.

(2) Authentication of content transmission client The content distribution server (CDS) that transmits the multicast content requests authentication from the home agent (HA) (for example, during a binding update) (step 11). It is assumed that information for authenticating the content distribution server (CDS) is registered in advance in the home agent (HA). If this authentication is successful, the home agent (HA) holds the correspondence between the home address of the content distribution server (CDS) and the care-of address, and sends the home address to the multicast control gateway (referred to as MCG1) corresponding to the care-of address. The care-of address and the authentication result are notified (step 12). Based on this notification, the multicast control gateway (MCG1) registers the home address and care-of address of the content distribution server (CDS) as the address of the authenticated content distribution server (CDS).

When a unicast packet transmitted from the content distribution server (CDS) or a unicast packet transmitted to the content distribution server (CDS) is received, the authenticated content distribution is performed based on the registered contents. It is determined that the packet originates from the server (CDS) or is addressed to the authenticated content distribution server (CDS), and is transferred.
(3) Content Reception Request Processing The viewer-side multicast control gateway (referred to as MCG2) is a gateway for a radio access area and manages area information related to a subordinate LAN (VLAN). At this time, when a client in the subordinate area issues a distribution request for a certain multicast content (step 13), the content reception client detection unit 16 of the multicast control gateway (MCG2) receives the distribution request. This distribution request includes the content identification information (multicast address) and area information.

  Next, the multicast control gateway (MCG2) requests the content mapping server (AMS) from the content attribute request unit 13 in order to request the attribute of the multicast content requested to be distributed to the content distribution server (CDS). A content attribute request message related to the content related to is sent (step 14). In the multicast control gateway (MCG2), it is assumed that the address and port number of the address mapping server (AMS) are preset in the configuration file or the like. The content attribute request message includes area information (including a network prefix, a VLAN ID under MCG2, etc.) of a delivery destination (location where the client exists).

  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 database 33 of the address mapping server (AMS) and collates the distributable area information for the requested content with the distribution destination area information included in the message. . If the content distribution is possible to the area where the client exists as a result of the collation, the address mapping server (AMS) notifies the content attribute from the content attribute transmission unit 32 to the MCG 2 (step 15). . The content attribute includes the home address of the content distribution server (CDS).

When the content attribute request unit 13 of the multicast control gateway (MCG2) receives the content attribute, the content attribute request unit 13 notifies the control unit 15 and the control unit 15 manages a pair of a distribution destination area and a multicast address as session information. Then, a content distribution request message is transmitted from the stream distribution request unit 14 of the multicast control gateway (MCG2) to the home address of the content distribution source server (CDS) (step 16). This content distribution request message includes the home address, the multicast address corresponding to the requested content, and the address of the request source MCG2.
(4) Content distribution tree creation A packet transmitted to the home address from the multicast control gateway (MCG2) is transmitted to the home agent (HA), and the content distribution server (CDS) having the home address from the home agent (HA). ) To the care-of address.

  Assume that there are some SP nodes in the middle of the communication path between the multicast control gateway (MCG2) and the home agent (HA) or in the middle of the communication path between the home agent (HA) and the content distribution server (CDS). . In the example of FIG. 18, it is assumed that there is a node called SP1 which is one splitter (SP), and SP1 is in the middle of the communication path between the multicast control gateway (MCG2) and the home agent (HA). At this time, the content distribution request message transmitted from the multicast control gateway (MCG2) to the home address of 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 session management unit 251 of the message. The session management unit 251 of the splitter (SP1) processes this request message as follows.

  (4.1) A pair of the address of the source MCG2 and the requested content channel (identification information (multicast address)) is managed as session information in the storage device (step 17).

  (4.2) The request source address of the content distribution request message is changed to the address of itself (SP1) instead of the original MCG2. Then, the rewritten content delivery request message is sent to the home address (step 18).

  The content distribution request message is then distributed to the home agent (HA), and the request message is transferred from the home agent (HA) to the content distribution server (CDS) (step 19). This request message passes through MCG1, but MCG1 determines that the content distribution server (CDS) has been authenticated, and permits transfer. When receiving the distribution request message, the content distribution server (CDS), not the home agent (HA), multicasts the requested content and the address of the source device (here SP1) immediately before the home agent (HA). A pair with an address is managed as session information.

(5) Stage of Content Relay and Multicast Distribution A content distribution server (CDS) that is a mobile IP client distributes requested content based on the held session information. In the above process, since SP1 is registered as the requested content distribution destination, the content is unicast-encapsulated to SP1 by unicast and stream-distributed (steps 20 and 21). The multicast control gateway (MCG1) determines that the content distribution server (CDS) has been authenticated, and transfers the unicast stream. This stream is transferred to the splitter (SP1) via the home agent (HA) (step 22).

  When receiving the unicast-encapsulated content stream, the stream receiving unit 24 of the splitter (SP1) performs transfer based on the session information managed by the session managing unit 25. Here, since the session for the multicast control gateway (MCG2) is managed, the stream is delivered from the stream delivery unit 22 to the multicast control gateway (MCG2) (step 23).

  The stream receiver 12 of the multicast control gateway (MCG2) receives content from the splitter (SP1). The multicast restoration unit 44 restores the content stream to multicast (step 24), and the stream distribution unit 11 distributes the content based on the session information managed by the management unit 15 (step 25). Here, since the session for the area where the client exists is managed, the content stream is distributed from the stream distribution unit 11 to the area by the multicast channel.

  In the above sequence example, there is one SP, but there may be no SP, or two or more SPs may exist.

(Concrete example)
Next, the embodiment of the present invention will be described more specifically using the network configuration shown in FIG. In the network shown in FIG. 19, it is assumed that each network device (device that relays packets in the network) communicates using IPv6 and is assigned an IPv6 address as shown in FIG.

  That is, areas 1 that correspond to prefixes 2001: 0: 1: 1 :: / 64, areas 2 that correspond to 2001: 0: 1: 2 :: / 64, and 2001, as areas that can be wirelessly accessed by clients. There is an area 3 corresponding to: 2: 1: 1 :: / 64. 2001: 0: 1: 1 :: / 64 and 2001: 0: 1: 2 :: / 64 are subordinate to the multicast control gateway (MCG1), and 2001: 2: 1: 1 :: / 64 is the multicast control gateway. It is under (MCG2).

  The address on the unicast network side (Internet side) of the multicast control gateway (MCG1) is 2001: 1: 1: 1 :: 2. On the other hand, the unicast network side (Internet side) address of the multicast control gateway (MCG2) is 2001: 2: 2: 1 :: 2.

  The address of the home agent (HA) is 2001: 9: 9: 9 :: 2. The content distribution server 1 (CDS1) is a mobile IPv6 client, and its home address is 2001: 9: 9: 9 :: 10. Further, in the state shown in FIG. 19, the content distribution server 1 (CDS1) exists in the area 1 corresponding to 2001: 0: 1: 1 :: / 64, so the care-of address is 2001: 0: 1: 1 ::. This care-of address is notified to the home agent (HA) using the mechanism of Mobile IPv6.

  The address mapping server (AMS) has an address of 2001: 8: 8: 8 :: 2, and holds the content attribute information shown in FIG. In the content attribute information, the content distribution server 1 (CDS1) distributes content to the multicast address ff08 :: 1: 1, and the content corresponding to the multicast address ff08 :: 1: 1 is the multicast control gateway (MCG2). ) Distribution to several areas including the subordinate prefix 2001: 2: 1: 1 :: / 64 network is permitted. The multicast control gateways (MCG1 and MCG2) read and recognize from the configuration file that an address mapping server (AMS) that manages such multicast content attributes exists in 2001: 8: 8: 8 :: 2. Suppose that

  Next, operations from the start of content request to the start of multicast distribution in the configuration of FIG. 19 will be described.

  It is assumed that the multicast distribution server 1 (referred to as CDS1) exists in 2001: 0: 1: 1 :: / 64 under the multicast control gateway (MCG1) and has been authenticated. First, when the client 1 requests content corresponding to the multicast address ff08 :: 1: 1, the content reception client detection unit 16 of the multicast control gateway (MCG2) receives a request message (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 multicast content.

  FIG. 21 shows an example of the content attribute request message. As shown in FIG. 21, the content attribute request message includes the network prefix of the distribution destination (in this case, 2001: 2: 1: 1 :: / 64). 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 database (content attribute shown in FIG. 20) and determines that the content corresponding to the requested multicast address can be distributed to the area 3 of the request source. As a result, the content attribute transmission unit 32 of the address mapping server (AMS) notifies the multicast control gateway (MCG2) of the content attributes shown in FIG.

  The stream delivery request unit 14 of the multicast control gateway (MCG2) uses the content attribute to send the multicast shown in FIG. 23 toward the content delivery server 1 (CDS1) (2001: 9: 9: 9 :: 10). A message requesting the content of the address (ff08 :: 1: 1) is transmitted.

  Since the content distribution server 1 (CDS1) is a mobile IPv6 client, the request message is received by the home agent (HA). The home agent (HA) transfers this message to the content distribution server 1 (CDS1) (care-of address 2001: 0: 1: 1 :: abcd).

  FIG. 24 shows the transfer route of the content distribution request message. Upon receiving the content distribution request message from the multicast control gateway (MCG2) transferred from the home agent (HA), the content distribution server 1 (CDS1) creates a content distribution session for the multicast control gateway (MCG2).

  Then, the content distribution server 1 (CDS1) unicasts the multicast content corresponding to ff08 :: 1: 1 distributed to the multicast control gateway (MCG2), and transmits this to the multicast control gateway (MCG2). Since the content distribution server 1 (CDS1) is a mobile IPv6 client, the stream from the content distribution server 1 (CDS1) to the multicast control gateway (MCG2) is transferred via the home agent (HA). FIG. 25 shows a stream distribution route.

  When the stream receiving unit 12 of the multicast control gateway (MCG2) receives the content, the multicast restoring unit 44 of the MCG2 restores the content corresponding to ff08 :: 1: 1 from the unicast packet to the multicast packet, and the MCG2 stream The distribution unit 11 performs multicast distribution of the content toward the area 3 where the client 1 exists.

  Here, the content distribution server 1 (CDS1) has moved from the network area 1 corresponding to 2001: 0: 1: 1 :: / 64 to the network area corresponding to 2001: 0: 1: 2 :: / 64. And The content distribution server 1 (CDS1) is a mobile IPv6 client and the home address remains unchanged at 2001: 9: 9: 9 :: 10, but in the area 2 corresponding to 2001: 0: 1: 2 :: / 64 Because it exists, the care-of address changes to 2001: 0: 1: 2 :: abcd. At this time, the content distribution server 1 (CDS1) notifies the home agent (HA) of this care-of address using the mechanism of Mobile IPv6. In addition, the content distribution server 1 (CDS1) is authenticated by the home agent (HA). Since AMS manages the home address of content distribution server 1 (CDS1), the address of content distribution server 1 (CDS1) managed by AMS does not require any change.

  At this time, in response to the multicast ff08 :: 1: 1 request from the client 1, the stream request message transmitted by the MCG 2 is sent to the home agent at the correct location of the content distribution server 1 (CDS1) as shown in FIG. (HA). Further, the stream distribution route from the content distribution server 1 (CDS1) is the route shown in FIG. Thereby, the multicast control gateway (MCG2) and the multicast clients under its control can continue to receive the multicast content (ff08 :: 1: 1) without being aware of the movement of the content distribution server 1 (CDS1).

  As described above, according to the multicast distribution system described in the present embodiment, when the multicast distribution distribution server moves, it automatically re-authenticates and switches the content distribution route. The movement of the multicast distribution server can be made unaware.

  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 1st Embodiment. It is a functional block diagram of the multicast control gateway in 1st Embodiment. It is a functional block diagram of the splitter in 1st Embodiment. It is a functional block diagram of the address mapping server in 1st Embodiment. It is a figure which shows the sequence from the delivery request | requirement of the content by the client in 1st Embodiment to the multicast delivery start of a content. It is a figure which shows the multicast delivery system in 1st Embodiment in detail. It is an example of the content attribute information which the address mapping server in 1st Embodiment hold | maintains. It is a figure which shows an example of the content of the content attribute request message in 1st Embodiment. It is a figure which shows an example of the content of the content attribute message transmitted from the address mapping server in 1st Embodiment. It is a figure which shows an example of the content of the stream delivery request message in 1st Embodiment. 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 the multicast delivery system in 2nd Embodiment. It is a functional block diagram of the multicast control gateway in 2nd Embodiment. It is a functional block diagram of the splitter in 2nd Embodiment. It is a figure which shows the sequence from the authentication of a content delivery server in 2nd Embodiment to the multicast delivery start of a content. It is a figure which shows the multicast delivery system in 2nd Embodiment in detail. It is an example of the content attribute information which the address mapping server in 2nd Embodiment hold | maintains. It is a figure which shows an example of the content of the content attribute request message in 2nd Embodiment. It is a figure which shows an example of the content of the content attribute message transmitted from the address mapping server in 2nd Embodiment. It is a figure which shows an example of the content of the stream delivery request message in 2nd Embodiment. It is a figure which shows the transfer path | route of the stream delivery request message corresponding to a multicast address (ff08 :: 1: 1). It is a figure which shows the stream delivery path | route corresponding to a multicast address (ff08 :: 1: 1). It is a figure which shows the transfer path | route of the stream delivery request message after a content delivery server moves. It is a figure which shows the stream delivery path | route after a content delivery server moved.

Explanation of symbols

1, 3 Multicast router 5 Client AMS address mapping server HA Home agent CDS Content distribution server SP Splitter MCG Multicast control gateway 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 41 HA communication unit 42 Authentication check unit 43 Packet filter unit 44 Multicast restoration 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

Claims (10)

A multicast control method in a multicast distribution system in which a content distribution device as a content transmission source, a multicast control device having a function of multicast distribution of content to clients, and a content attribute information management device are connected to a communication network. ,
The content attribute information management device holds a database for managing content identification information, content distribution device address, and content distributable area information in association with each content,
When the multicast control apparatus receives a content distribution request including content distribution destination area information and content identification information from a client under its control, a content attribute request including the content distribution destination area information and the content identification information is received. Transmitted to the content attribute information management device,
The content attribute information management device that has received the content attribute request refers to the database based on the content attribute request to obtain the content corresponding to the content identification information for the area corresponding to the content distribution destination area information. It is determined whether or not distribution is possible, and if it is possible, information including the address of the content distribution device that is the transmission source of the content is transmitted to the multicast control device,
The multicast control method, wherein the multicast control device transmits the content distribution request to a content distribution device that is a transmission source of the content, and multicast distributes the received content to the area.   The multicast control according to claim 1, wherein the content distribution device has a mobile IP function, and the content attribute information management device holds a home address of the content distribution device as an address of the content distribution device. Method. The multicast distribution system includes a home agent of the content distribution device and a gateway device under the content distribution device,
The home agent authenticates the content distribution device based on an authentication request from the content distribution device, and transmits the address information of the content distribution device to the gateway device when authentication is successful,
The gateway device holds address information of the content distribution device, determines whether the received packet is a packet transmitted from the content distribution device or a packet addressed to the content distribution device based on the address information, The multicast control method according to claim 2, wherein the packet is transferred when the packet is transmitted from the content distribution device or the packet is addressed to the content distribution device. Multicast control apparatus used in a content distribution apparatus that is a content transmission source, a multicast control apparatus having a function of multicast distribution of contents to clients, and a multicast distribution system configured by connecting a content attribute information management apparatus to a communication network Because
When a content distribution request including content distribution destination area information and content identification information is received from a client under the control of the multicast control device, a content attribute request including the content distribution destination area information and the content identification information is transmitted to the content Means for transmitting to the attribute information management device;
Content information receiving means for receiving, from the content attribute information management device determined to be capable of distributing content corresponding to the content identification information, information including an address of a content distribution device that is a transmission source of the content;
Means for transmitting the content distribution request to a content distribution device that is the transmission source of the content;
Means for multicast distribution of received content to an area corresponding to the content distribution destination area information.   The content distribution device that is the transmission source of the content has a mobile IP function, the content attribute information management device holds a home address of the content distribution device as an address of the content distribution device, and the content information receiving unit includes: 5. The multicast control apparatus according to claim 4, wherein information including a home address of the content distribution apparatus is received from the content attribute information management apparatus. The multicast distribution system includes a home agent of the content distribution device, and when the multicast control device has the content distribution device under control, the multicast control device
From the home agent that authenticated the content distribution device, the address information of the content distribution device is received, and the address information is retained.
It is determined based on the address information whether the received packet is a packet transmitted from the content distribution device or a packet addressed to the content distribution device, and a packet transmitted from the content distribution device or addressed to the content distribution device is determined. The multicast control device according to claim 5, wherein the packet is transferred when it is a packet. Content attribute information used in a content distribution device that is a content transmission source, a multicast control device having a function of multicast distribution of content to clients, and a multicast distribution system configured by connecting a content attribute information management device to a communication network A management device,
Storage means for holding a database for managing content identification information, content distribution device address, and content distributable area information in association with each content;
Means for receiving a content attribute request including content distribution destination area information and content identification information from the multicast control device;
Based on the content attribute request, it is determined whether or not the content corresponding to the content identification information can be distributed to the area corresponding to the content distribution destination area information by referring to the database. A content attribute information management apparatus comprising: means for transmitting information including an address of a content distribution apparatus as a transmission source of the content to the multicast control apparatus.   The content distribution device has a mobile IP function, and the content attribute information management device holds a home address of the content distribution device in the database as an address of the content distribution device. Content attribute information management device. Multicast control apparatus used in a content distribution apparatus that is a content transmission source, a multicast control apparatus having a function of multicast distribution of contents to clients, and a multicast distribution system configured by connecting a content attribute information management apparatus to a communication network As a program for causing a computer to function as a computer,
When a content distribution request including content distribution destination area information and content identification information is received from a client under the control of the multicast control device, a content attribute request including the content distribution destination area information and the content identification information is transmitted to the content Means for transmitting to the attribute information management device;
Means for receiving, from the content attribute information management device determined to be capable of distributing content corresponding to the content identification information, information including the address of the content distribution device that is the transmission source of the content;
Means for transmitting the content distribution request to a content distribution apparatus that is a transmission source of the content;
Means for multicast distribution of received content to an area corresponding to the content distribution area information;
Program to function as. Content attribute information used in a content distribution device that is a content transmission source, a multicast control device having a function of multicast distribution of content to clients, and a multicast distribution system configured by connecting a content attribute information management device to a communication network A program for causing a computer to function as a management device,
Means for referring to the database held in the storage means for managing the content identification information, the content distribution device address, and the content distributable area information in association with each content;
Means for receiving a content attribute request including content distribution destination area information and content identification information from the multicast control device;
Based on the content attribute request, it is determined whether or not the content corresponding to the content identification information can be distributed to the area corresponding to the content distribution destination area information by referring to the database. Means for transmitting information including an address of a content distribution device that is a transmission source of the content to the multicast control device;
Program to function as.

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