JP4554420B2 - Gateway device and program thereof - Google Patents

Description

  The present invention relates to multicast technology, and more particularly to technology for grasping which client is receiving multicast content.

  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

  Now, when grasping whether or not the client is communicating, in the case of unicast communication, since the IP address of the client is included in the communication packet as the source or destination, the client can check by checking the communication packet. It is possible to easily grasp whether or not communication is in progress. On the other hand, in the case of the multicast communication described in the above prior art, the communication packet includes the IP address of the content distribution server as the transmission source and the multicast address as the transmission destination, and does not include information identifying the client that receives the multicast. Therefore, it is difficult to determine whether or not the client is communicating from the multicast packet.

  However, in multicast communication, whether there is a client receiving the multicast is a query message (in some cases, it is expressed as IGMP Query for IPv4, MLD Query for IPv6, and hereinafter referred to as IGMP / MLD Query). It can be grasped using. In other words, a query message is periodically distributed to the target area, and a response is received from any client (in some cases, it is expressed as IGMP Report if IPv4, MLD Report if IPv6, hereinafter referred to as IGMP / MLD Report). If there is, it can be seen that there is a client that is receiving a specific multicast (participating in a multicast group) in the area.

  However, in the conventional technology, when one client in the area sends a response indicating that the multicast is being received, the response message is also multicast to other clients in the area, and the same multicast is transmitted. Other receiving clients do not send a response. Therefore, in the prior art, it is possible to grasp whether or not there is a client that is receiving a multicast in the area. However, when there are a plurality of clients in the same area, which client is receiving the multicast is determined. I can't figure it out. For this reason, for example, when a client views a multicast via login authentication, this client detects that even if the client has finished receiving the multicast but remains logged in for a long time because it does not log out. There is a problem that can not be.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a technique for grasping the reception state of multicast content for each client.

The above-described problem is a gateway device that detects a client that is receiving multicast content, and that holds an MAC address of the authenticated client in association with the client, and a state in which multicast content is being received. A query message sending means for sending a query message to return a response message to a client; and when a response message to the query message is received from one client, the response message is not delivered to the other clients, A response message receiving means for receiving a response message from another client in addition to a response message from one client, and a MAC address included in the response message received by the response message receiving means. When, by collating the MAC address held in said address holding means, have a detection means for detecting a client in a multicast content reception individually, the response message receiving means, detecting a client no communication The response message received from one client for the transmission of one query message is not delivered to other clients for a part of the predetermined period for In the other period, a response message received from one client in response to transmission of one query message can be solved by a gateway apparatus characterized in that it is distributed to other clients .

  A wireless access point may be connected to the gateway device, and the wireless access point may be set to transmit the response message to the gateway device without distributing it to the client side.

Further, the gateway device, in the part of the period in the predetermined period of time, may further comprise an automatic logout means to log out the client that has not been detected as a client in a multicast content reception.

Also, the period of the part may be as said is a part of the part and the second half of the first half in the predetermined time period.

  According to the present invention, when a response message to the query message is received from one client, the response message is not delivered to the other clients, and from other clients in addition to the response message from the one client. By receiving the response message and identifying the client from the received response message, it is possible to individually detect the client that is receiving the multicast content, so it is possible to grasp the reception status of the multicast content for each client Become.

  In addition, by providing means for logging out a client that has not been detected as a client that is receiving multicast content during a predetermined period, it is possible to automatically log out a non-communication client. In addition, the response message received from one client for the transmission of one query message is not delivered to other clients for a part of the predetermined period, and the other messages in the predetermined period are not delivered. In the period, the response message can be efficiently transmitted by distributing the response message received from one client to the other clients in response to the transmission of one query message.

  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) having a mobile IPv6 node function, an address mapping server (AMS), a multicast control gateway (MCG). Server), a splitter (SP), and a home agent (HA) are connected to the IP network.
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 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.

  The address mapping server (AMS), for each content, a multicast address corresponding to the content (which may be referred to as a multicast channel or a multicast group) and attributes of the content (the home address of the content distribution source server, the content) Distribution 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 unicast-encapsulated content distributed along the content distribution tree is restored to multicast, and 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 multicast control gateway (MCG) has a function of an authentication gateway and a function of individually grasping clients that are receiving multicast.

  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.

  A home agent (HA) is a device (for example, a router) having a mobile IPv6 home agent function (defined in draft-ietf-mobileip-ipv6), and manages a home address and a care-of address 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). ).

  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. However, content distribution from the content distribution server (CDS) is performed as unicast by encapsulating IP multicast packets into unicast packets. 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 or not the content can be received in the area from the received information, and if possible, the information including the home address of the content distribution server (CDS) is transmitted to the multicast control gateway. Returning to (MCG), 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.

  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 an authentication check unit 17, a packet filter unit 18, 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 multicast restoration unit. 19, HA communication unit 10, no communication monitoring unit 9, client authentication unit 20, and control unit 15. The control unit 15 includes an authentication state management unit 151, a session management unit 152, and an area information management 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 IGMP Report or MLD Report. Further, the content reception client detection unit 16 transmits a query message for detecting the presence of the content reception client. The content reception client detection unit 16 also has a function of returning a response packet to the query message to the client.

  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 server (CDS) or the splitter (SP). The stream receiving unit 12 receives content stream-distributed from a content distribution 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 HA communication unit 10 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 no-communication monitoring unit 9 has a function of checking whether an authenticated client is in unicast or multicast communication, automatically logging out a client that has not communicated for a certain period of time, and setting it to an unauthenticated state.

  The authentication check unit 17 has a function of checking whether or not the packet is information transmitted from an authenticated client from the header information of the received IP packet. Further, when receiving an IP packet from the client, the packet filter unit 18 forwards the packet to its destination if it is transmitted from the authenticated client. Otherwise, it is discarded except for exceptions (binding information notification to the HA, etc.).

  The client authentication unit 20 has a function for authenticating the client. In addition, the client authentication unit 20 displays a WWW authentication screen on the client, performs authentication by comparing the ID and password stored in the storage device in advance with the ID and password received from the client, and succeeds in authentication. In some cases, it may have a function of accepting login.

  The multicast restoring unit 19 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 authentication state management unit 151 of the control unit 15 holds and manages the IP address (global address) and MAC address of the authenticated client in the storage device. The session management unit 152 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 153 of the control unit 15 has a function of managing area information for each VLAN under the gateway.

  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. Further, the control unit 25 has a session management unit 251.

  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 a stream transmission / reception session with the downstream splitter (SP), the multicast control gateway (MCG), and the upstream splitter (SP) or content distribution server (CDS).

  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 units in each of the above devices and each means of the present invention are realized by causing a computer to execute a program describing the processing contents 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. 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) Content Distribution Server Authentication 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). Here, the client requesting the content is authenticated first, and this process will be described in detail later.

  Further, when a client that has completed the authentication process sends a request for distribution of a certain multicast content (step 13), it is checked whether the distribution request is sent from an authenticated client. Detailed description.

  When a multicast distribution request is issued in 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. To do. 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 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). ) Will be forwarded to the care-of address.

  In the present embodiment, some SPs are 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). A node exists. In the example of FIG. 6, 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 a source MCG2 address and a 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. Note that “a tree has been created” means that session information corresponding to specific content is held in each of the above nodes.

(5) Stage of Content Relay and Multicast Distribution The content distribution server (CDS), which 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 management unit 25. Here, since a 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). Then, the multicast restoration unit 19 restores the content stream to multicast (step 24), and the stream delivery unit 11 delivers the content based on the session information managed by the session management unit 152 (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 using a multicast channel.

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

  Further, the content distribution server (CDS) may not have a mobile IP function. In this case, the IP address of the content distribution server (CDS) is registered in the AMS, and packets transmitted from the content distribution server (CDS) and packets addressed to the content distribution server (CDS) do not pass through the HA. The other processes are the same as when the mobile IP function is provided.

(Client authentication)
Hereinafter, the authentication check process of the content reception client in the (3) content reception request process will be described in detail with reference to the sequence chart of FIG. By this processing, only authenticated clients can request multicast.

(3.1) Log-in of Content Receiving Client First, a client who is going to make a content distribution request is authenticated. The authentication method is not limited to a specific method. For example, if the client has a mobile IPv6 function, the home agent (HA) authenticates the client by the mobile IP function, and if the authentication is OK, the home agent (HA) uses the client's global IP address (home address). Is notified to the HA communication unit 10 of the multicast control gateway (MCG2), and the HA communication unit 10 notifies the HA to the authentication state management unit 151. The authentication state management unit 151 stores the address as the address of the authenticated client. Store and manage. In addition, even when the client does not have the mobile IP function, the client can access the home agent (HA) by providing the home agent (HA) with the function of authenticating the client without the mobile IP function. A home agent (HA) can perform authentication.

  Further, authentication may be performed by performing IPsec negotiation between the client and the multicast control gateway (MCG2), and the multicast control gateway (MCG2) may acquire the address of the authenticated client. Alternatively, the multicast control gateway (MCG2) may provide an authentication WWW page to the client, receive the input of the ID and password from the client, and authenticate the client by comparing with an ID and password registered in advance.

  In the example shown in FIG. 7, the home agent (HA) authenticates the client (step 31), notifies the multicast control gateway (MCG2) of the global IP address of the client that has been successfully authenticated (step 32). The authentication status management unit 151 is notified (step 33).

Then, the multicast control gateway (MCG2) accesses the client using the acquired IP address (step 34), thereby acquiring the client MAC address, and the authentication state management unit 151 sets the acquired MAC address as the IP address. It manages in association (steps 35 and 36).
(3.2) Content reception request (multicast join)
In order to make a multicast distribution request, the client sends Join (IGMP Report for IPv4 multicast, MLD Report for IPv6 multicast). FIG. 7 shows the case of IPv6 multicast.

  In the case of IPv4 multicast, the authentication check unit 17 of the multicast control gateway (MCG2) uses the IP address in which the combination of the source IP address and the MAC address of the IGMP Report is held by the process (3.1). And whether it matches one of the MAC address pairs. If there is no match, the join is discarded. If they match, the processing from step 16 in FIG. 6 is performed to perform multicast distribution. When a content attribute request is made and a response indicating that the content can be distributed to the requested area is received, the packet filter unit 18 opens a distribution filter for the area of the content.

  On the other hand, in the case of IPv6 multicast, since the source IP address of the MLD Report is a link local address, it is not possible to check the match with the global IP address as in the case of IPv4 multicast. Therefore, in this embodiment, it is checked whether the MLD Report is a packet from an authenticated client as follows.

  As shown in FIG. 7, first, the authentication check unit 17 of the multicast control gateway (MCG2) acquires a source MAC address (referred to as MAC1) from the MLD Report packet received from the client (steps 37 and 38). It is checked whether the MAC1 matches any of the information acquired and managed in the step (3.1). If there is no match, the distribution request is discarded.

If there is a MAC address that matches MAC1, the authentication check unit 17 acquires a global IP address corresponding to MAC1 from the authentication state management unit 151 (steps 39 and 40). Then, the IP address acquired from the authentication state management unit 151 is set as a target address in the IPv6 Neighbor Solicitation packet, and the Neighbor Solicitation packet is transmitted to the client side area (step 41).
When a response packet (Neighbor Advertisement (neighbor advertisement)) is notified from the client having the IP address that has received this packet (step 42), the MAC address (MAC2) of the packet is checked. It is checked whether they match (step 43). When MAC2 matches MAC1, it can be determined that the client that transmitted the response packet is a client having an IP address held in association with MAC1, that is, an authenticated client. Therefore, when MAC2 matches MAC1, it is determined that the client that has transmitted the MLD Report in step 37 is an authenticated client (step 44).

Note that the above MLD Report packet authentication check is performed on the MLD Report packet that is first transmitted to join the multicast group for each client.
(3.3) Content distribution area check In response to the multicast distribution request accepted in the authentication check in (3.2), the multicast control gateway (MCG2) performs the same processing as steps 14 and 15 in FIG. A content distribution area check is performed (steps 45 to 49). If a response indicating that the distribution is possible is received, the filter of the packet filter unit 18 is opened (step 50 in FIG. 7). Thereafter, the processing from step 16 shown in FIG. 6 is performed to request content from the content distribution server (CDS), and the MCG 2 performs multicast distribution of the stream received by unicast to the request area (step 51).

(Process to identify individual clients receiving multicast)
Next, a process for individually grasping clients that are receiving multicast and automatically logging out clients that have not received multicast for a certain period of time will be described. In the following description, an authentication server connected to the network provides an authentication WWW page to the client, receives an ID and password from the client, and authenticates the client by comparing it with a pre-registered ID and password. The login is accepted, and the address information (global IP address and MAC address) of the client whose login has been authenticated is notified to the multicast control gateway (MCG2) together with the client ID, held in the storage device, and managed by the authentication status management unit 151. Shall.

As described above, in the prior art, when there are a plurality of clients in the same area, it is impossible to individually identify the clients that are receiving the multicast. However, in this embodiment, the processing described below is performed. It solves this problem by running.
(1) First, turn off the return of the multicast packet of the wireless access point (AP) under the multicast control gateway (MCG2).

  A response (IGMP / MLD Report) packet from the client to the IGMP / MLD Query is a multicast packet, and is normally multicast-distributed from the wireless access point (AP) to other clients in the same area. When the response packet is transmitted from the client, the wireless access point (AP) always transfers the packet only to the multicast control gateway (MCG2), and the response packet is not transmitted to the client side. . That is, the multicast control gateway (MCG2) can acquire all response packets transmitted from each client toward the wireless access point (AP). By performing this setting, it is possible to perform automatic logout of a non-communication client as shown in FIG.

  In FIG. 8, first, when an authenticated client sends a multicast distribution request (IGMP / MLD Report) to view multicast content, the content reception client detection unit 16 receives it. Then, the multicast control gateway (MCG2) checks whether the IGMP / MLD Report packet is transmitted from the authenticated client by the method described in FIG. 7, and if it is transmitted from the authenticated client. For example, the client can receive the content. Information indicating that the client is a client in multicast communication is recorded in the storage device (communication terminal list) in association with the address information.

  The content reception client detection unit 16 periodically transmits IGMP / MLD Query to the client side area. The no-communication monitoring unit 9 identifies which client the response packet is by comparing the MAC address included in the response packet to the IGMP / MLD Query with the MAC address in the address information, and transmits the response packet. In association with the client, information indicating that a response packet to the IGMP / MLD Query has been transmitted is recorded. This makes it possible to detect clients that are actually performing multicast communication.

  Further, the no-communication monitoring unit 9 checks the no-communication client every predetermined period (T1). That is, paying attention to a client recorded as a communicating client by sending an IGMP / MLD Report, it checks whether or not the client has returned a response packet to the IGMP / MLD Query within the period T1. Specifically, for each T1 period, it is checked for each client in communication whether information indicating that a response packet has been transmitted to the IGMP / MLD Query is recorded. For a client for which information indicating that a response packet has been transmitted is not recorded, the information indicating that communication is in progress is deleted, and the client is requested to log out to the authentication server, etc. Do.

  When the client also performs unicast communication, the no-communication monitoring unit 9 monitors whether or not each client is performing unicast communication by monitoring IP packets passing through the MCG 2, and multicast communication. Logout processing may be performed when both unicast communication and unicast communication are not performed.

(2) Streamlined IGMP / MLD Report transmission As described above, the multicast control gateway (MCG2) is set so that the response packet from each client for IGMP / MLD Query can be received, so that multicast reception is performed for each client. It can be determined whether or not. However, it is not desirable from the viewpoint of device load or the like that all clients receiving a multicast every time an IGMP / MLD Query is transmitted transmits a response packet.

  Therefore, the multicast control gateway (MCG2) determines whether or not the multicast packet should be transferred to the client under the wireless access point (AP), and only the packet to be transferred is placed under the wireless access point (AP). A process of blowing back (turning back) is performed. Conventionally, when a wireless access point (AP) receives a multicast packet transmitted from a client, the wireless access point (AP) transfers the multicast packet to another client. It will be performed by the multicast control gateway (MCG2), not (AP). Thereby, the efficiency of the IGMP / MLD Report transmission is realized.

  Specifically, when the purpose is to detect a non-communication client, it is not necessary to check the response of the IGMP / MLD Query of each client during the entire predetermined timeout period, for example, the first half and the second half of the timeout period. Focusing on the fact that it is sufficient to check the response of IGMP / MLD Query with only a part of the above, the following processing is performed.

  As shown in FIG. 9, when T1 is the time until automatic logout (timeout) and T2 is the interval for transmitting IGMP / MLD Query, T2 in the first half of T1 and T2 in the second half Only the period without the return of the IGMP / MLD Report is set, and the IGMP / MLD Report is returned for the remaining period. The control unit 15 performs control of the non-turnback / turnback period, and the content reception client detection unit 16 performs the return processing.

  As a result, during the IGMP / MLD Report non-turnback period, it is possible to collect IGMP / MLD reports from all the clients that are receiving the multicast, and to check the communicating clients. In addition, during the period of turning back IGMP / MLD Report, other clients receiving the same multicast do not need to respond IGMP / MLD Report to the multicast control gateway (MCG2), and the load of IGMP / MLD Report processing is improved. Can be

  Now, the timeout detection period T1 is determined from the viewpoint of automatic logout, and if it is too short, the number of cases where the user must log in again increases. It is determined in consideration of the fact that if it is too long, useless charges will be generated for the user. On the other hand, the interval T2 for transmitting the IGMP / MLD Query is determined from the viewpoint of checking whether or not there is a client that is receiving content, and stopping content distribution if there is no client that is receiving content. For example, if the service provider wants to stop content distribution as soon as there are no clients receiving content, T2 is shortened. Thus, since T1 and T2 are determined independently, there are various cases in the relationship between the length of T1 and the length of T2.

  For example, in the case of the relationship between the lengths of T1 and T2 as shown in FIG. 9, the automatic logout judgment can be accurately determined by providing the non-turnback period once in T1 / 2 as shown in FIG. And the load on the IGMP / MLD report process can be made efficient. In the case of FIG. 9, a client that has not responded within T1 is automatically logged out. Further, in the case of FIG. 9, it is possible to automatically log out a client that has not responded in two non-turnback periods.

  On the other hand, for example, when both T2 is longer than T1 / 2 and both the non-turnback period and the turnaround period are provided, there is a possibility that the automatic logout detection cannot be performed accurately due to the occurrence of the IGMP / MLD Report being missed. is there.

  Therefore, in the present embodiment, when T1 / 2> T2, as shown in FIG. 9, an IGMP / MLD Report non-turnback period is provided once during T1 / 2, and IGMP / MLD Report is provided during the other periods. We are going to do the wrapping. Further, when T1 / 2 <T2 and T1 / 2 = T2, no IGMP / MLD Report loopback period is provided, and IGMP / MLD Report is not loopback distributed over the entire period. In the present embodiment, the half period (T1 / 2) of the no-communication monitoring period (T1) is used because of a difference in timing between the Query transmission & report collection period and the no-communication monitoring period. It should be noted that the non-turnback period only needs to appear at least once during T1 / 2, and the non-turnback period need not appear every fixed period.

  This will be described more specifically with reference to FIG. In the example shown in FIG. 10, it is assumed that the period from time t = 0 to t = T1 is a no-communication monitoring period, and multicast reception is performed once in this half period (time t = 0 to t = T1 / 2). All of the clients transmit IGMP / MLD Report, indicating that it is possible to grasp that communication is in progress. Further, as shown in FIG. 10, in the time period (time T2) from when the IGMP / MLD Query is transmitted from the multicast control gateway (MCG2) at time t = τ and then the next Query is transmitted at t = τ + T2. Even if the control gateway (MCG2) receives IGMP / MLD Report from a client under the wireless access point (AP), the control gateway (MCG2) does not make a return to the wireless access point (AP). Therefore, all the clients that are receiving the multicast can send out IGMP / MLD Report, and can grasp all the clients that are receiving. In other periods (for example, the period from time t = τ + T2 to t = τ + 2T2), since the IGMP / MLD Report is returned to the subordinate of the AP, not all clients can be grasped, and the minimum necessary IGMP Check only / MLD.

(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. 11, 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. In addition, in the state shown in FIG. 11, 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. In addition, it is set whether or not a client requesting content distribution needs to be authenticated. In the case of “necessary”, the content attribute is provided when the content attribute request message includes information indicating that the client who has requested the content distribution is authenticated.

  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. 11 will be described.

  Here, it is assumed that the multicast distribution server 1 (CDS1) exists in 2001: 0: 1: 1 :: / 64 under the multicast control gateway (MCG1) and has been authenticated. In addition, it is assumed that the client 1 requesting the content has already 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. Then, when it is checked in the procedure described with reference to FIG. 7 that the request message is sent from an authenticated client, the multicast control gateway (MCG2) acquires the attribute of the requested multicast content. The content attribute request message is transmitted from the content attribute request unit 13 to the address mapping server (AMS).

  FIG. 13 shows an example of the content attribute request message. As shown in FIG. 13, the content attribute request message is distributed in addition to the multicast address of the content requesting distribution and the network prefix of the distribution destination (in this case, 2001: 2: 1: 1 :: / 64). The result of authentication check of the client requesting

  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. 12), and the content corresponding to the requested multicast address can be distributed to the requesting area 3, and the client who made the distribution request has been authenticated. Is determined. 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 having the contents shown in FIG.

  The stream distribution request unit 14 of the multicast control gateway (MCG2) uses the content attribute to send to the content distribution server 1 (CDS1) (2001: 9: 9: 9 :: 10) as shown in FIG. 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. 16 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. 17 shows a stream distribution route.

  When the stream receiving unit 12 of the multicast control gateway (MCG2) receives the content, the multicast restoring unit 19 of the MCG2 restores the content corresponding to ff08 :: 1: 1 from the unicast packet to the multicast packet. Based on the session information, the stream distribution unit 11 performs multicast distribution of the content toward the area 3 where the client 1 exists. Thereafter, as described with reference to FIGS. 8 to 10, it is possible to perform processing such as detecting a client that is receiving a multicast and logging out a non-communication client.

  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 Since it exists, the care-of address changes to, for example, 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 request of multicast ff08 :: 1: 1 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, by setting the database in the address mapping server, the content distribution server and the content distribution destination area can be specified for each content. It is possible to reflect a policy that contents are multicast-distributed only to clients in the network, and it is possible to dynamically construct a content distribution tree according to this policy.

  In addition, according to the multicast distribution system described in the present embodiment, it is possible to determine whether or not the client that has transmitted the MLD Report is an authenticated client, and to permit a content distribution request only to the authenticated client. Can be realized.

  Further, according to the multicast distribution system described in the present embodiment, it is possible to detect for each client whether multicast communication is in progress, and logout can be automatically performed for a non-communication client.

  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 the multicast control gateway in the embodiment of the present invention. It is a functional block diagram of the splitter in the embodiment of the present invention. It is a functional block diagram of the address mapping server in the embodiment of the present invention. It is a figure which shows the sequence from the authentication of a client and a content delivery server in the embodiment of this invention to the multicast delivery start of a content. It is a sequence chart for demonstrating the authentication check process of a content reception client. It is a figure for demonstrating the detection process of a non-communication client. It is a figure which shows the example of a setting of the no turn-back period of IGMP / MLD Report. It is a figure for demonstrating concretely the setting of the non-turnback period of IGMP / MLD Report. It is a figure which shows in detail the multicast delivery system in embodiment of this invention. It is an example of the content attribute information which the address mapping server in embodiment of this invention hold | maintains. It is a figure which shows an example of the content of the content attribute request message in embodiment of this invention. It is a figure which shows an example of the content of the content attribute message transmitted from the address mapping server in embodiment of this invention. It is a figure which shows an example of the content of the stream delivery request message in embodiment of this invention. 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-compatible router 5 Client AMS address mapping server HA Home agent CDS Content distribution server SP Splitter MCG Multicast control gateway 9 Non-communication monitoring unit 10 HA communication unit 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 Authentication check unit 18 Packet filter unit 19 Multicast restoration unit 20 Client authentication 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 receiving unit 32 Content attribute transmitting unit 33 Content attribute management database 34 Attribute operation user interface unit 35 Part

Claims (7)

A gateway device for detecting a client receiving multicast content,
Address holding means for holding the MAC address of the authenticated client in association with the client;
A query message sending means for sending a query message for returning a response message to a client in a state of receiving multicast content;
When a response message for the query message is received from one client, the response message is not delivered to other clients, and a response message from another client is received in addition to the response message from the one client A response message receiving means,
There is a detecting means for individually detecting clients receiving multicast contents by comparing the MAC address included in the response message received by the response message receiving means with the MAC address held in the address holding means. And
The response message receiving means receives the response message received from one client in response to the transmission of one query message only during a part of a predetermined period for detecting a non-communication client. In the other period of the predetermined period, a response message received from one client in response to the transmission of one query message is distributed to the other client .   The gateway device according to claim 1, wherein a wireless access point is connected to the gateway device, and the wireless access point is set to transmit the response message to the gateway device without distributing it to the client side. The gateway device is
2. The gateway device according to claim 1, further comprising automatic logout means for logging out a client that has not been detected as a client that is receiving multicast content during the partial period of the predetermined period . 4. The gateway device according to claim 1, wherein the partial period is a part of the first half and a part of the second half of the predetermined period. 5. A program that causes a computer to function as a gateway device that detects a client that is receiving multicast content,
Address storage means for storing the MAC address of the authenticated client in the storage device in association with the client,
A query message sending means for sending a query message for sending back a response message to a client in a state of receiving multicast content;
When a response message for the query message is received from one client, the response message is not delivered to other clients, and a response message from another client is received in addition to the response message from the one client A response message receiving means,
A program that functions as a detecting unit that individually detects clients that are receiving multicast content by collating the MAC address included in the response message received by the response message receiving unit with the MAC address held in the storage device And
The response message receiving means receives the response message received from one client in response to the transmission of one query message only during a part of a predetermined period for detecting a non-communication client. In response to the transmission of one query message, the response message received from one client is distributed to the other clients in the other period within the predetermined period.
A program characterized by that. The computer, in the portion of the period in the predetermined period, the program according to claim 5 which further functions as an automatic logout means to log out the client that has not been detected as a client in a multicast content reception. The program according to claim 5 or 6, wherein the partial period is a part of the first half and a part of the second half of the predetermined period.

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