Method for managing multicast addresses for transmitting and receiving multimedia conferencing information on an internet protocol (IP) network implemented over an ATM network

• US 6,138,144 A
• Filed: 06/24/1997
• Issued: 10/24/2000
• Est. Priority Date: 06/24/1997
• Status: Expired due to Term

• Current Assignee: RPX Corporation
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: DeSimone, Antonio, Golan, Joseph, Kuthyar, Ashok K., Parent, Bryant Richard, Ramamurthy, Ram S., Shur, David Hilton
• Primary Examiner(s): Asta, Frank J.
• Assistant Examiner(s): YUAN, ALMARI ROMERO
• Application Number:
  US08/881,763
• Time in Patent Office: 1,218 Days
• Field of Search: 709/204, 709/205, 709/227, 709/229, 709/245
• US Class Current: 709/204
• CPC Class Codes: H04L 12/18 for broadcast or conference , e.g. multicast
• CPC Class Codes: H04L 2101/663 Transport layer addresses, e.g. aspects of transmission control protocol [TCP] or user datagram protocol [UDP] ports
• CPC Class Codes: H04L 61/10 of different types
• CPC Class Codes: H04L 61/45 Network directories; Name-to-address mapping
• CPC Class Codes: H04L 61/5007 Internet protocol [IP] addresses
• CPC Class Codes: H04L 61/5069 for group communication, multicast communication or broadcast communication
• CPC Class Codes: H04L 61/5076 Update or notification mechanisms, e.g. DynDNS
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/168 specially adapted for link layer protocols, e.g. asynchronous transfer mode [ATM], synchronous optical network [SONET] or point-to-point protocol [PPP]
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

In a multicast capable IP network implemented over an ATM network, each client terminal on a multimedia conference, for each media type it transmits, is assigned a multicast IP address and a port number (together known as a socket) on which to transmit packets, wherein each assigned multicast IP address is unique and different than the multicast IP address assigned to any other client for any media type. Each client terminal then selects, for each media type, which clients on the conference it wants to receive packets from. Only packets that are in fact requested by a client are routed over the multicast IP network to the requesting client. A single special purpose Multicast Address Resolution System (MARS) server is associated with the conference when the conference is established. Each client terminal uses that MARS server, whether on the same or different IP sub-networks, but on a common ATM network, for purposes of mapping the multicast IP addresses used in the conference into a set of unicast ATM endpoint addresses used by the ATM-connected client terminals. Similarly, when a specific conference uses a Multicast Server, a single special purpose Multicast Server is used for all clients on the conference, whether on the same or different IP sub-networks, for purposes of establishing point-to-multipoint ATM connections to the conference endpoints.

Claims

1. In a multicast capable IP network comprising plural IP sub-networks implemented over a common switched virtual circuit in which, during a multimedia conference, at least one of a plurality of clients in the multimedia conference, at an associated unicast endpoint address, transmits packets for multicast transmission to at least some of the plurality of clients in the multimedia conference at their respective unicast endpoint addresses using multicast IP addresses, a method comprising:

assigning a server connected to the network for use during the multimedia conference for managing mapping between the multicast IP addresses, to which said at least one of said plurality of clients transmits packets, and the unicast endpoint addresses of each of the at least some of the plurality of clients receiving such transmitted packets, wherein

the packets are packets of plural media types, at least one of the plurality of clients selects one or more of the plural media types that the at least one client chooses to receive from the other of the plurality of clients in the multimedia conference, and wherein only packets of the selected one or more of the plural media types are transmitted to the at least one client; and

assigning to each of the plurality of clients in the multimedia conference, for each media type, a different unique multicast IP address on which to transmit packets when each of the plurality of clients joins the multimedia conference.

2. The method of claim 1, wherein the packets of plural media types are transmitted on different multicast IP addresses and the server manages mapping for each media type between the multicast IP address to which said at least one of said plurality of clients transmits packets of that media type and the unicast endpoint addresses of each of the at least some of the plurality of clients receiving transmitted packets of that media type.

3. The method of claim 2 wherein the plural media types are at least one of audio, video and/or data.

4. The method of claim 1 wherein the virtual circuit network is an ATM network, the clients are connected to the ATM network via ATM, and the endpoint addresses are ATM addresses.

5. The method of claim 2, wherein the server maintains for each multicast IP address a set of the unicast endpoint addresses of those clients in the multimedia conference which are currently receiving transmissions on that multicast IP address.

6. The method of claim 1, further comprising:

assigning a special purpose Multicast Server connected to the network for use for that multimedia conference for establishing point-to-multipoint connections to the clients at their unicast endpoint addresses.

7. The method of claim 1, wherein the multicast IP addresses assigned to each of the plurality of clients in the multimedia conference are from a group of multicast IP addresses allocated to the multimedia conference when the multimedia conference is initiated.

8. In a multicast capable IP network comprising plural IP sub-networks implemented over a common switched virtual circuit on which packets are transmitted by a plurality of clients on multicast IP addresses for multicast transmission, a method for a client at a unicast endpoint address to join a multimedia conference and receive transmissions from at least one other client in the multimedia conference at another unicast endpoint address, the method comprising the steps of:

providing to the joining client an endpoint address of a server assigned for use for the conference, which server maintains for each multicast IP address a set of all the unicast endpoint addresses of those clients in the multimedia conference which receive transmissions on the multicast IP address;

receiving a request from the joining client to receive transmissions from the at least one other client; and

adding, in the server, the unicast endpoint address of the joining client to a group of endpoint addresses associated with the particular multicast IP address on which the at least one other client transmits, wherein the transmissions are transmissions of plural media types, each media type is assigned a different multicast IP address for each of the plurality of clients, and wherein the multicast IP addresses are assigned from a group of multicast IP addresses allocated to the multimedia conference when the multimedia conference is initiated.

9. The method of claim 8 further comprising the step of instructing the at least one other client to add the joining client as an additional endpoint on a point-to-multipoint virtual circuit to the group of endpoint addresses to which the at least one other client transmits on the particular multicast IP address.

10. The method of claim 8, wherein the transmissions include packets of plural media types transmitted by the at least one other client on different multicast IP addresses, and the request from the joining client includes a request to receive transmissions from the at least one other client of packets of at least one of the plural media types.

11. The method of claim 10 wherein the plural media types are at least one of audio, video and/or data.

12. The method of claim 10, further comprising:

assigning to the joining client, for each media type for which packets are transmitted, a multicast IP address on which to transmit such packets that is different and unique from any multicast IP address assigned to any other client in the multimedia conference.

13. The method of claim 12, wherein the multicast IP addresses assigned to the joining client are from a group of multicast IP addresses allocated to the multimedia conference.

14. The method of claim 8 wherein the virtual circuit network is an ATM network, the joining client and the other clients are connected to the ATM network via ATM, and the unicast endpoint addresses are ATM addresses.

15. The method of claim 8, further comprising:

providing, to the joining client, an endpoint address of a single special purpose Multicast Server assigned for use during the multimedia conference, which Multicast Server establishes point-to-multipoint connections to clients in the multimedia conference;

establishing a virtual connection between the joining client and the special purpose Multicast Server;

providing the endpoint address of the joining client to the Multicast Server; and

adding the endpoint address of the joining client to the Multicast Server'"'"'s point-to-multipoint connections.

16. In a multicast capable IP network comprising plural IP sub-networks implemented over a common switched virtual circuit in which, during a multimedia conference, at least one of a plurality of clients in the multimedia conference, at an associated unicast endpoint address, transmits packets for multicast transmission to at least some of the plurality of clients in the multimedia conference at their respective unicast endpoint addresses using multicast IP addresses, a method comprising:

assigning a server connected to the network for use during the multimedia conference for managing mapping between the multicast IP addresses, to which said at least one of said plurality of clients transmits packets, and the unicast endpoint addresses of each of the at least some of the plurality of clients receiving such transmitted packets, wherein

the packets are packets of plural media types, at least one of the plurality of clients selects one or more of the plural media types that the at least one client chooses to receive from the other of the plurality of clients in the multimedia conference, and wherein only packets of the selected one or more of the plural media types are transmitted to the at least one client;

identifying a maximum number of clients for the multimedia conference; and

pre-assigning a fixed number of multicast IP addresses to the multimedia conference based on the identified maximum number of clients.

17. The method of claim 16, further comprising:

assigning a subset of the fixed number of multicast IP addresses to one of the plurality of clients when the one of the plurality of clients joins the multimedia conference, the subset of the fixed number of multicast IP addresses including an multicast IP address for each media type.

18. In a multicast capable IP network comprising plural IP sub-networks implemented over a common switched virtual circuit in which, during a multimedia conference, at least one of a plurality of clients in the multimedia conference, at an associated unicast endpoint address, transmits packets for multicast transmission to at least some of the plurality of clients in the multimedia conference at their respective unicast endpoint addresses using multicast IP addresses, a method comprising:

assigning a server connected to the network for use during the multimedia conference for managing mapping between the multicast IP addresses, to which said at least one of said plurality of clients transmits packets, and the unicast endpoint addresses of each of the at least some of the plurality of clients receiving such transmitted packets, wherein

the packets are packets of plural media types, at least one of the plurality of clients selects one or more of the plural media types that the at least one client chooses to receive from the other of the plurality of clients in the multimedia conference, and wherein only packets of the selected one or more of the plural media types are transmitted to the at least one client and the at least one client may choose to receive packets of different media types from different ones of the other clients of the plurality of clients.

19. The method of claim 18, wherein the multicast IP addresses for the other clients of the plurality of clients corresponding to the selected media types, are added to an address list associated with the at least one client.

20. The method of claim 18, wherein the server instructs the other clients of the plurality of clients to add a multicast IP address for the at least one client to distribution trees associated with the other clients.

21. The method of claim 18, further comprising:

identifying a maximum number of clients for the multimedia conference; and

pre-assigning a fixed number of multicast IP addresses to the multimedia conference based on the identified maximum number of clients.