MXPA99009712A - System, device, and method for managing multicast group memberships in a multicast network - Google Patents

Abstract

A system (300, 400, 500), device (1200), and method (600) for managing multicast group memberships in a multicast network uses IGMP spoofing to consolidate the multicast group memberships of a number of multicast hosts into a single IGMP Host. The IGMP spoofing agent maintains a group list indicating the multicast group membership status for the number of multicast hosts. The IGMP spoofing agent establishes a multicast group membership with a remote multicast device when at least one of the number of mulicast hosts requests membership in the multicast group. The IGMP spoofing agent cancels the multicast group with the remote multicast device when all of the multicast hosts have left the multicast group. The IGMP spoofing agent responds to status inquiries from the remote multicast device as a proxy on behalf of the number of multicast hosts.

Description

SYSTEM, DEVICE AND METHOD FOR ADMINISTERING MEMBERSHIPS OF SELECTIVE MULTI-EASY GROUP IN A SELECTIVE MULTIMEDIA NETWORK. BACKGROUND 1. Field of the Invention. This invention relates generally to communication systems and, more particularly, to the administration of selective multi-broadcast group memberships in a selective multi-broadcast network. 2. Related Technique In the current information age, there is a growing demand for access to information using computer network services such as the Internet. Some types of information are suitable for use by multiple IPs, for example, news, financial information and sports scores. These information IPos can be packaged by a single producer, and transmitted through the computer network to a large number of consumers. A typical way for the producer to transmit information to consumers is to duplicate the information and send a copy to each consumer. However, if there is a large number of consumers, these individual transmissions may require a large amount of processing by the producer, and may also require a large amount of bandwidth of the network. SUMMARY OF THE INVENTION An improved way for the producer to transmit the information to the consumers is through a selective multiemission service. The selective multi-broadcast service allows the producer to transmit a single message, which is then repeated through the network at appropriate points and sent to each consumer who is a member of a selective multi-broadcast group. Repetition is typically handled by means of routers in the network, and is done only when needed. For convenience, a router that supports the selective multicast service is referred to as a selective multicast router. In an Internet Draft entitled Introduction to Semeria and Maufer IP Selective Multi-Direction Management, which is incorporated herein for reference, a general view of selective multiemission can be found. In order to support the selective multicast service, each selective multicast router typically supports at least one selective multicasting addressing protocol, which is used to exchange information of selective multicast group members between the various selective multicast routers in the net. Currently, there are several selective multicast addressing protocols. Examples of selective multicast addressing protocols include the Distance Vector Multicast Routing Protocol.

(DVMRP)), First Shortest Open Path of Selective Multicast (Multicast Open Shortest Path First (MOSPF)) and the Multicast Protocol Independent Selective (Protocol Independent Multicasting (PIM)). In addition to supporting selective multi-destination routing protocols, each selective multicast router that has directly connected LANs will typically support the Internet Group Management Protocol (IGMP) as described in the Internet Appendix I RFC 1112 (IGMP Version 1) and in the Internet Draft entitled Internet Group Management Protocol, Fenner Version 2 (IGMP Version 2). A selective multicast address uses IGMP to learn which selective multicast groups have members in each of their connected physical networks. The selective multicast router maintains a database containing a list of selective multicast group members for each of its connected networks, where the "selective multicast group membership" means the presence of at least one member of a group selective multicast in a given connected network. The selective multicast router does not maintain a list of all group members from its connected networks. For convenience, the list of selective multi-member group memberships is referred to as the "group list". IGMP is used between the selective multicast router and its directly connected IP central computers (for example, central computers in directly connected LANs that support the IP protocol). By using IGMP, the IP central computers can join and leave selective multicast groups, and the selective multicast router can monitor the members of the selective multicast group of their IP central computers. For convenience, the selective multicast router directly connected to a central IP computer is referred to as the local router (from the perspective of the central IP computer), while the other routers in the network are referred to as remote routers. IGMP defines a number of message types that can be exchanged between the local router and the central IP computers. The IGMP Query message is used by the local router to determine the selective multicast group memberships for their directly connected IP central computers. The IGMP Membership Report message is sent through an unsolicited central IP computer when you want to join a particular selective multicast group and also in response to an IGMP Query message to report your continued membership in a group of selective selective multiemission. The Abandon IGMP message is used by a central IP computer to remove itself explicitly from a selective group of people. For convenience, a device that sends IGMP Query messages (for example, the local router) is referred to as an IGMP Consultant, and a device that sends IGMP Membership Report messages and Leave IGMP messages (for example, a computer central IP) is referred to as an IGMP Central Computer. The local router typically sends IGMP query messages to the IP central computers to retrieve the group membership information. IGMP defines two types of query messages, specifically a General Query message and a Specific Group Query message. The General Query message is sent to determine which (if any) of the available selective multicast groups has at least one member of the central IP computers directly connected to the local router. In response to the General Inquiry message, each central IP computer transmits an IGMP Membership Report message for each of its selective multi-member group memberships. However, since each central IP computer is typically capable of monitoring the responses of other central IP computers in the same LAN, a central IP computer that detects a response from another central IP computer for a group of IPs. Particular selective issuance may not transmit an IGMP Membership Report message for that same group. Accordingly, the local director can receive a single IGMP Membership Report for each selective multicast group, even if the multiple central IP computers are members of the same group. The Group Specific Query message is sent to determine if at least one of the directly connected IP central computers is a member of the specified selective multicast group. At least one central IP computer that is a member of the specified group will respond to the Specific Group Query message with an IGMP Membership Report message (again, as regards the General Query message, a central computer IP that is a member of the specified group, will transmit only one response if it has not detected a response from any other central IP computer in the group). When a central IP computer wants to be removed from a particular selective group, stop reporting your membership in the group (that is, do not transmit the IGMP Membership Report to the particular group). By not transmitting the IGMP Membership Report message to a particular selective multicast group, the IP central computer implicitly requests the removal of the group. An IP central computer that supports IGMP Version 2 can explicitly request the removal of a selective multicast group by transmitting a Leave IGMP message to the local router. The Abandon IGMP message informs the local router that the IP central computer is no longer a member of the selective multicast group, and, after receiving the Abandon IGMP message, the local router typically transmits a Group Inquiry message IGMP specific to determine if at least one central IP computer continues to be a member of the selective multicast group. Figure 1 shows a system 100 in which a selective multicast addressing protocol is used between the local router and the selective multicast network, and IGMP is used for the dynamic group registration between the local router and a number of central computers of IP (typically personal computers). The overall responsibility for maintaining group membership is divided between the local router and the central IP computer. IP central computers act as IGMP Central Computers, and the local router acts as an IGMP Consultant. The current model for maintaining a group membership through selective multi-network inter-networks forces the local di rector to participate in one or more complicated selective multicast addressing protocols in order to propagate group information to other selective multi-destination routers . The existing selective multicast addressing protocols are complex, and, because of this complexity, they have been changed frequently. This fact makes each protocol difficult to implement and maintain. Also, since no protocol has been adopted as a standard for all routers, it is often necessary for a selective multicast address to support many of the protocols, which adds significant cost to the manager. These same problems exist in a data system -by- cable (DOC). Figure 2 shows an exemplary DOC system in which a router of the central node (i.e., a local router) 210 couples to a plurality of cable modems 220: to 220n through a shared channel 230. Each central node router can support thousands of cable modems, each cable modem representing a single LAN segment having at least one central computer. As previously mentioned in Figure 1, the central node router must support selective multicast addressing protocols in order to exchange information from the selective multicast group through the selective multicast network.

Therefore, a need remains for a system, device and method for downloading the selective multicast addressing protocols from local routers in a selective multicast network. BRIEF DESCRIPTION OF THE DRAWING In the drawing, Figure 1 shows a selective multi-transmission network as is known in the art; Figure 2 shows a DOC system as known in the art; Figure 3 shows a selective and j jective multiemission system in which the IGMP simulation in the local router allows you to use IGMP between the remote router and the local router; Figure 4 shows an interactive DOC system in which the IGMP simulation in the central node router allows it to use IGMP between the remote router and the central node router; Figure 5 shows an exemplary DOC system in which the IGMP simulation in the central node router allows you to use IGMP between the selective multicast server and the central node router; Figure 6 is a flowchart for the simulation of IGMP in a selective multiview network; Figure 7 is a flow chart for processing an IGMP Membership Report message from a selective multicast central computer by means of the IGMP simulation agent; Figure 8 is a flow diagram for monitoring the selective multi-broadcast group memberships by means of the simulation agent of IGMP; Figure 9 is a flow diagram for processing an Abandoned IGMP message received from a selective multicast central computer by means of the IGMP simulation agent; Figure 10 is a flow chart for processing an IGMP General Query message received by the IGMP simulation agent from the remote selective multicast device; Figure 11 is a flow diagram for processing an IGMP Specific Group Query message received by the IGMP simulation agent from the remote selective multicam device; and Figure 12 shows a device for the simulation of IGMP in a selective multicast network. DETAILED DESCRIPTION As previously discussed, there remains a need for a system, device and method for downloading selective multicast addressing protocols from local routers in a selective multicast network. The present invention works by replacing the selective multicast addressing protocols in the local router with an IGMP simulation agent. The local router continues to act as an IGMP Consultant on its central computer interfaces (that is, on connections from the local LAN to directly connected central IP computers). However, instead of using a selective multicast addressing protocol to exchange selective mute group membership information with the remote router, the local router and the remote router use IGMP. The remote router assumes the functions of an IGMP Consultant, while the IGMP simulator agent in the local router assumes the functions of an IGMP central computer. The IGMP simulation agent appears as an IGMP central computer for the remote router, and uses the selective multi-member group membership information through the local router to act as a commissioner on behalf of its directly connected IP central computers. . The IGMP simulation agent joins a group of highly selective broadcasting, and leaves the selective multicast group when the last of its directly connected IP central computers leaves the group. The drawing shows a number of applications for the simulation of IGMP in a multi-broadcast network selective Figure 3 shows a selective multiemission system ej empl i f icat ívo 300 in which simulation of IGMP in the local router allows to use IGMP between the remote router and the local router. Figure 4 shows a DOC exemplary system 400 in which the IGMP simulation in the central node router allows IGMP to be used between the remote router and the central node router. Figure 5 shows a DOC and j empl i f icat ive system 500 in which the IGMP simulation in the central node router allows using IGMP between the selective multicast server and the central node router. In these modalities ej empl íf icat ívoes, the IGMP simulation agent performs functions of standard IGMP central computer in order to consolidate the selective multi-broadcast group memberships and present them to the remote selective multi-broadcast device as a single IGMP central computer. The IGMP simulation reduces the cost and complexity of the local router, since the local router does not need to support any of the selective multicast address protocols. IGMP simulation can also reduce the cost and complexity of the remote selective multicast device (for example, the remote router or server), which is required only to support IGMP on the network interface to the local router. If the remote selective multicast device is a selective multicast server, then the selective multicast server does not need to support any of the selective multicast addressing protocols, so the cost and complexity of the selective multicast server are reduced. A flow chart for the IGMP simulation in a selective multicast network is shown in Figure 6. The logic maintains a group list indicating the status of the selective multi-member group membership for the number of selective multicast central computers . When at least one of the selective multi-destination central computers requires membership in a selective multicast group, the logic establishes a selective multi-broadcast group membership with the remote selective uttering device on behalf of the selective multicast central computers. The logic maintains the selective multi-broadcast group membership with the remote selective multicast device as long as at least one of the selective multicast central computers continues to be a member of the selective multicast group. When all the selective multicast hosts have left the selective multicast group, the logic cancels the selective multicast group membership with the remote selective multicast device so that the remote selective multicast device does not send more selective multicast messages towards the IGMP simulation agent. The logic also responds to the state requirements from the remote selective multicast device as a commissioner representing the number of selective multicast central computers. When a selective multi-destination central computer requires membership in a selective multicast group, the IGMP simulation checks the database to determine whether the specified selective multicast group is in the group list. If the selective multicast group is in the group list, then the central selective multicast computer does not need to add any action to the group. However, if the selective multicast group is not in the group list, then the IGMP simulation agent adds the selective multicast group to the group list and sends an IGMP Membership Report message to the multicast device remote selective that specifies the group of selective time. A flow chart is shown for processing an IGMP Membership Report message received from a selective multicast central computer by means of the IGMP simulation agent in Figure 7. The logic is the same whether the message of Membership Report IGMP is received without request or in response to an IGMP Query message. The logic begins at step 710, and after receiving an IGMP Membership Report message from a selective multicast central computer in step 720, proceed to step 730 where it checks the database to determine whether the selective multicast group It is in the group list. If the selective multicast group is not in the group list (NOT in step 740), then the logic adds the selective multicast group to the group list, in step 750 and sends an IGMP Membership Report message to the remote selective multicast device in order to request membership in the selective multicast group, in step 760. The logic ends in step 799.

The IGMP simulation agent also monitors the selective multi-broadcast group memberships of its selective multicast central computers by periodically sending the status requirements (eg, the IGMP Query messages) to the selective multicast central computers. Specifically, the IGMP simulation agent uses functions from the standard IGMP Consultant to determine which (if any) of the selective multicast groups in the group list are no longer needed. For each group not needed, the IGMP simulation agent deletes the group from the group list and if IGMP Version 2 is supported, it sends a message leaving IGMP for the remote selective multicast device requesting the removal of the selective multicast group. A flowchart for storing the selective multi-broadcast group memberships by means of the IGMP simulation agent in Figure 8 is shown. The logic begins at step 810 and proceeds to step 820, where the logic uses the functions of the consultant of IGMP standard to determine which (if any) of the selective multicast groups in the group list are no longer needed. For each group not needed (YES in step 830), the logic deletes the group from its group list, in step 840, and sends a message leaving IGMP to the selective multicast device requesting the elimination of the selective multicast group (if IGMP Version 2 is supported), in step 850. When the non-needed groups have been removed from the group list (NOT in step 830), the logic in step 899 ends. As discussed previously, the computers Selective multicast exchanges that support IGMP Version 2 can explicitly request the removal of a selective multicast group by sending a message leaving IGMP to the local router. A flow chart for processing a received message is shown leaving IGMP from a selective multicast central computer by means of the IGMP simulation agent in Figure 9. The logic begins at step 910 and after receiving the message let IGMP on step 920 proceeds to step 930 where it uses functions of the standard IGMP Consultant to determine whether at least one of the selective multicast central computers supported by the local router continues to be a member of the selective time group. If there are no longer any members remaining in the selective multicast group (NOT in step 940), then the logic clears the selective multicast group from the group list, in step 950, and sends a message leaving IGMP to the device. remote selective multicam requesting the elimination of the selective multicast group (if the IGMP Version 2 is supported), in step 960. The logic ends in step 999. In addition to maintaining the status of the selective multicast group memberships for the Selective multicast central computer, the IGMP simulation agent also responds to the state requirements from the remote selective multicast device such as a commissioner representing the selective multicast central computers. The remote selective multicast device sends the IGMP Query messages to the IGMP simulation agent as part of its IGMP Consultant functionality. The IGMP simulation agent responds to state requirements using standard IGMP Membership Report messages. A flowchart for processing an IGMP General Query message received by the IGMP simulation agent from the remote selective multiscreening device is shown in Figure 10. The logic begins at step 1010 and after it receives a message. IGMP General Consultation in step 1020, access the database to obtain the group list, in step 1030 and send a message of IGMP membership to the remote selective multicast device for each selective multicast group in the group list. The logic ends in step 1099. A flow chart is shown to process an IGMP Specific Group Query message received by the IGMP simulation agent from the remote selective multicast device in Figure 11. The logic begins in the step 1110 and after it receives an IGMP Specific Group Query message in step 1120, proceed to step 1130 where you verify the database to determine if the specified multicast group is in the group list. If the selective multicast group is in the group list (YES in step 1140), then the logic sends an IGMP Membership Report message to the selective remote multicast device for the selective multicast group, in step 1150, and ends at step 1199. Figure 12 shows a device 1200 for simulating IGMP in a selective multicast network. The device 1200 includes a network interface 1210 for making the interface with another selective multicast device (such as a remote selective multicast server or router) or a selective multicast network. The device 1200 also includes a core computer interface 1230 to make the interface with a number of selective multi-destination central computers. An IGMP simulation agent 1220 performs the functions of IGMP Consultant on the interface of the central computer 1230 to manage the selective multicast group memberships for the selective multicast central computers, and performs the functions of the IGMP central computer on the interface interface 1210 network to act as a commissioner on behalf of its selective multi-mission central computers. The IGMP simulation agent 1220 maintains selective multi-broadcast group membership information for its selective multi-destination central computers connected to a 1240 database which is updated each time a group membership is established or canceled. While the IGMP simulation technique has been described as relating the central node router of a DOC system or other local router, it will be apparent to an experienced craftsman that the present invention can also be used in other devices such as a remote router, a server remote access, or an IP switch. When the simulation technique is used in a remote address, the remote router will administer the selective multicast group memberships for its local and remote connected routers that also support the IGMP simulation. The present invention can be incorporated into other specific forms without deviating from the spirit or essential characteristics. The described modalities are considered in all aspects only as illustrative and not restrictive.

Claims (10)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore the property described in the following claims is claimed as property. A method for managing selective multi-broadcast group memberships between a remote selective multi-broadcast device and a number of selective multi-destination central computers in a selective multi-broadcast network, the method comprising the steps of: maintaining a group list indicating the selective multi-member group membership status for the number of selective multi-destination central computers; establish a selective multi-broadcast group membership with the remote selective multi-broadcast device when at least one of the number of selective multi-destination central computers requests membership in the selective multi-broadcast group; and cancel the selective multi-broadcast group membership with the remote selective multicast device when all the selective multicast central computers have left the selective multicast group. The method according to claim 1, characterized in that the step of establishing the selective multi-broadcast group membership with the remote selective multi-broadcasting device comprises the steps of: receiving a membership report message from a selective multi-broadcast central computer specifies one of a plurality of selective multicast groups; determine if the specified selective multicast group is in the group list; and where the specified selective multicast group is absent from the group list: add the specified selective multicast group to the group list; and sending a membership report message to the remote selective multicast device that specifies the selective multicast group. The method according to claim 1, characterized in that the step of canceling the selective multi-broadcast group membership with the remote selective multi-broadcasting device comprises the steps of: sending a status request towards the number of selective multi-destination central computers; receive a membership report for the selective multicast group from at least one of the number of selective multicast central computers if the selective multicast group is needed; delete the selective multicast group from the group list if no membership report is received for the selective multicast group; and where selected, send to the remote selective multicast device a request to leave the selective multicast group after clearing the selective multicast group from the group list. The method according to claim 1, characterized in that the step of canceling the selective multi-broadcast group membership with the remote selective multicast device I comprises the steps of: receiving a request to leave the specified selective multicast group from a computer selective multi-broadcast center; determining whether at least one of the plurality of selective multicast central computers continues to be a member of the specified selective multicast group; wherein at least one of the plurality of selective multiemission central computers continues to be a member of the specified selective multicast group, leaving the selective multicast group specified in the group list; where none of the plurality of selective multicast central computers continues to be a member of the specified selective multicast group, erasing the specified selective multicast group from the group list; and where selected, send to the remote selective multicast device a request to leave the selective multicast group after clearing the selective multicast group from the group list. 5. The method according to claim 1, characterized in that it also comprises the step of: responding to the status requirements from the remote selective multi-broadcast device as a commissioner representing the number of selective multi-destination central computers. The method according to claim 5, characterized in that the step of responding to status requirements from the remote selective multi-transmission device comprises the steps of: receiving a query message from the remote selective multi-transmission device requesting the status of at least a selective multi-member group membership; wherein the inquiry message requests the status of all selective multi-broadcast group memberships, by sending a membership report message to the remote selective multi-broadcast device for each selective multicast group in the group list; where the query message requests the status of a specified selective multicast group membership, verifying the database to determine whether the specified selective multicast group is in the group list and sending a membership report message to the device remote selective multicast group for the specified selective multicast group if the specified selective multicast group is in the group list. 7. A device for managing selective multi-broadcast group memberships for a number of selective multi-destination central computers in a selective multi-broadcast network, the device comprising: a network interface to make the interface with the selective multi-broadcast network; a central computer interface to make the interface with the number of selective multicast central computers; a database to store selective multi-member group membership information; and an IGMP simulation agent that supports both the IGMP Central Computer functionality and the IGMP Consultant functionality; wherein: the IGMP simulation agent is operatively coupled to the database to maintain the selective multi-member group membership status for the number of selective multi-destination central computers; the IGMP simulation agent is operatively coupled to the network interface to support the functionality of the IGMP central computer; and the IGMP simulation agent is operatively coupled to the central computer interface to support the functionality of the IGMP Consultant. The device according to claim 7 characterized in that the IGMP simulation agent comprises: logic for maintaining a group list indicating the selective multi-member group membership status for the number of selective multi-destination central computers; logic for establishing a selective multi-broadcast group membership with the remote selective multicast device when at least one of the number of selective multi-destination central computers requests membership in a selective multi-broadcast group; and logic for canceling the selective multi-broadcast group membership with the remote selective multicast device when all selective multicast central computers have left the selective multicast group. 9. The device according to the claim 8, characterized in that the IGMP simulation agent further comprises: logic for responding to the status requirements from the remote selective multicast device as a commissioner representing the number of selective multicast central computers. 10. A system for managing the selective multi-broadcast group memberships in a selective multi-broadcast network, the system comprising: a remote selective multi-broadcast device that supports the functionality of the IGMP Consultant; at least one selective multicast central computer that supports IGMP central computer functionality; and a local selective multicast device operably coupled to the remote selective multicast device to support IGMP central computer functionality and operatively coupled to at least one selective multicast central computer to support the functionality of the IGMP Consultant. SUMMARY A system (300, 400, 500), device (1200), and method (600) for managing selective multi-broadcast group memberships in a selective multicast network that uses IGMP simulation to consolidate selective multi-group group memberships of a number of selective multicast central computers in a single IGMP central computer. The IGMP simulation agent maintains a group list indicating the selective multi-member group membership status for the number of selective multicast central computers. The IGMP simulation agent establishes a selective multi-broadcast group membership with a remote selective multicast device when at least one of the number of selective multi-destination central computers requests membership in the selective multicast group. The IGMP simulation agent cancels the selective multicast group with the remote selective multicast device when all selective multicast central computers have left the selective multicast group. The IGMP simulation agent responds to the status requirements from the remote selective multicast device as a commissioner representing the number of selective multicast central computers.