Method for a unicast endpoint client to access a multicast internet protocol (IP) session and to serve as a redistributor of such session

• US 6,181,697 B1
• Filed: 03/31/1998
• Issued: 01/30/2001
• Est. Priority Date: 03/31/1998
• Status: Expired due to Term

• Current Assignee: AT&T Intellectual Property II LP (AT&T, Inc.)
• Original Assignee: AT&T Corporation (AT&T, Inc.)
• Inventors: Zelezniak, Aleksandr, Shur, David Hilton, Nurenberg, Steven Howard
• Primary Examiner(s): Hsu, Alpus H.
• Assistant Examiner(s): Qureshi, Afsar M.
• Application Number:
  US09/052,028
• Time in Patent Office: 1,036 Days
• Field of Search: 370/389, 370/390, 370/262, 370/401, 370/432, 370/352, 370/354, 370/353, 370/355, 370/356, 370/383, 370/392, 370/408, 370/410, 709/201, 709/203, 709/238, 709/227, 709/228
• US Class Current: 370/390
• CPC Class Codes: H04L 12/1836 with heterogeneous network architecture
• CPC Class Codes: H04L 12/1854 with non-centralised forwarding system, e.g. chaincast
• CPC Class Codes: H04L 61/2503 Translation of Internet protocol [IP] addresses
• CPC Class Codes: H04L 67/14 Session management for real-time applications in data packet communications networks H04L65/1066
• CPC Class Codes: H04L 67/56 Provisioning of proxy services store-and-forward switching systems in data switching networks H04L12/54
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]

Abstract

A endpoint client (111-1) on an IP Unicast network (107) that is provided access to a Multicast session on an IP Multicast network (101) through a Multicast-Unicast gateway server (MUS) (120) is enabled to re-Multicast that session to other endpoint clients (111-2) on the network to which it is connected or to endpoint clients (134, 135) on any Multicast-capable sub-network (132) to which it is directly connected. To act as a re-Multicaster, the endpoint client receiving Unicast-addressed packets from the session from the MUS, re-translates these Unicast-addressed packets to Multicast-addressed packets by translating the Unicast address in the distribution field of each packet'"'"'s header into a Multicast address and overwriting the Unicast address in each header with the Multicast address. When an endpoint client on the same or connected sub-network as the re-Multicaster desires to join a session that is being re-Multicast, it needs only connect to that Multicast address. A endpoint client on a Unicast network can elect to be a re-Multicaster of packets from a session as long as that same session is not being re-Multicast by another endpoint client on any sub-network on which the electing re-Multicaster is connected or a Multicast router is not forwarding packets from the session onto the sub-network.

Claims

1. A method of providing access to a Multicast session on a Multicast network to a requesting client connected to the same sub-network as a client on a Unicast network or to a Multicast-capable sub-network directly connected to the client on the Unicast network, the method comprising the steps of:

receiving at a gateway server packets from the Multicast session on a Multicast address;

re-addressing at the gateway server the Multicast address of the packets from the session to a Unicast address of the client on the Unicast network;

sending the re-addressed packets to the client on the Unicast network;

re-re-addressing the packets received by the client on the Unicast network with a Multicast address; and

re-Multicasting the re-re-addressed packets to the requesting client.

2. The method of claim 1 wherein the re-re-addressed packets are addressed with the same Multicast address on which they were received at the gateway server.

3. A method for a first client on a Unicast network, which is receiving Unicast-addressed packets from a Multicast session on a Multicast network from a gateway server, to provide the packets to another client on a same sub-network as the first client is connected on the Unicast network or to another client on a Multicast-capable sub-network directly connected to the first, the method comprising the steps of:

re-addressing the received packets with a Multicast address; and

re-Multicasting the re-addressed packets on the same sub-network and/or on the directly connected Multicast-capable sub-network.

4. The method of claim 3 wherein the received packets are re-addressed with a Multicast address that is a Multicast address for the session on the Multicast network.

5. The method of claim 3 further comprising the steps of:

determining whether a second client connected on the same sub-network as the first client or on the directly Multicast-capable sub-network is re-Multicasting packets from the session; and

if the second client is re-Multicasting packets from the session, determining whether the first or the second client is to re-Multicast the packets from the session.

6. The method of claim 5 further comprising the step of:

if the step of determining whether the first or second client is to re-Multicast determines that the first client will re-Multicast, halting re-Multicasting of the packets by the second client.

7. The method of claim 5 further comprising the step of:

if the step of determining whether the first or second client is to re-Multicast determines that the second client will re-Multicast, inhibiting the step by the first client of re-Multicasting the packets.

8. The method of claim 5 wherein the step of determining whether the first or second client is to re-Multicast comprises the step of determining which client has a lower IP address.

9. The method of claim 3 further comprising the steps of:

determining whether a router is distributing packets from the session on the locally connected sub-network; and

if it is determined that a router is distributing packets, inhibiting the first client from re-Multicasting packets from the session.

10. The method of claim 9 wherein the step of determining whether a router is distributing packets comprises listening for packets on a Multicast address on which the session is Multicast.

11. The method of claim 9 wherein the first client is inhibited from re-Multicasting packets only when the router is distributing packets from the session and the first client resumes re-Multicasting packets when it is determined that the router is not distributing packets from the session.

12. A method for a first client on a Unicast network, which is receiving Unicast-addressed packets from a Multicast session on a Multicast network from a gateway server, the method comprising the step of:

re-Multicasting the received packets to another client on a same sub-network on the Unicast network on which the first client is connected or on a Multicast-capable sub-network directly connect to the first client.

13. The method of claim 12 wherein these step of re-Multicasting comprises the step of:

re-addressing the received packets with a Multicast address.

14. The method of claim 13 wherein the received packets are re-addressed with a Multicast address that is a Multicast address for the session on the Multicast network.

15. The method of claim 13 further comprising the steps of:

determining whether a second client connected on the same sub-network as the first client or on the directly Multicast-capable sub-network is re-Multicasting packets from the session; and

if the second client is re-Multicasting packets from the session, determining whether the first or the second client is to re-Multicast the packets from the session.

16. The method of claim 15 further comprising the step of:

if the step of determining whether the first or second client is to re-Multicast determines that the first client will re-Multicast, halting re-Multicasting of the packets by the second client.

17. The method of claim 15 further comprising the step of:

if the step of determining whether the first or second client is to re-Multicast determines that the second client will re-Multicast, inhibiting the step by the first client of re-Multicasting the packets.

18. The method of claim 15 wherein the step of determining whether the first or second client is to re-Multicast comprises the step of determining which client has a lower IP address.

19. The method of claim 13 further comprising the steps of:

determining whether a router is distributing packets from the session on the locally connected sub-network; and

if it is determined that a router is distributing packets, inhibiting the first client from re-Multicasting packets from the session.

20. The method of claim 19 wherein the step of determining whether a router is distributing packets comprises listening for packets on a Multicast address on which the session is Multicast.

21. The method of claim 19 wherein the first client is inhibited from re-Multicasting packets only when the router is distributing packets from the session and the first client resumes re-Multicasting packets when it is determined that the router is not distributing packets from the session.