Method and apparatus for transparently multicasting identical data streams originating from different or common sources

• US 6,512,776 B1
• Filed: 06/15/1998
• Issued: 01/28/2003
• Est. Priority Date: 06/15/1998
• Status: Expired due to Term

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Roberts, Philip R., Jones, Wesley Stuart
• Primary Examiner(s): Nguyen, Steven
• Assistant Examiner(s): DUONG, DUC T
• Application Number:
  US09/097,337
• Time in Patent Office: 1,688 Days
• Field of Search: 370/432, 370/328, 370/338, 370/401, 370/402, 370/403, 370/404, 370/349, 370/389, 370/473, 709/203
• US Class Current: 370/432
• CPC Class Codes: H04L 12/1886 with traffic restrictions for efficiency improvement, e.g. involving subnets or subdomains
• CPC Class Codes: H04L 12/189 in combination with wireless systems selective distribution or broadcast in wireless communication networks H04W4/06
• CPC Class Codes: H04L 45/00 Routing or path finding of packets in data switching networks routing or path finding in wireless networks H04W40/00
• CPC Class Codes: H04L 45/16 Multipoint routing
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/611 for multicast or broadcast systems for broadcast or conference H04L12/18; arrangements for broadcast or distribution combined with broadcast H04H20/00; arrangements for broadcast applications with a direct linkage to broadcast information or to broadcast space-time H04H60/00; selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS], H04W4/06
• CPC Class Codes: H04L 69/22 Parsing or analysis of headers

Abstract

A first data stream (26) requested by a first client (1) is received at a router (16). A second data stream (24) requested by a second client (2) is also received at the router (16). The router (16) determines that the first data stream (26) and the second data stream (24) are identical. The router (16) multicasts the first data stream (26) and the second data stream (24) into a single multicast data stream (28). The single multicast data stream (28) is transmitted to the first client (1) and to the second client (2).

Claims

1. A method for multicasting identical data streams, wherein each data stream is comprised of a plurality of packets, at a router for simultaneous receipt by multiple users comprising, at the router:

receiving a first data stream requested by a first client;

receiving a second data stream requested by a second client;

determining that the first data stream and the second data stream are identical;

multicasting the first data stream and the second data stream into a single multicast data stream; and

transmitting the single multicast data stream to the first client and to the second client.

2. The method according to claim 1 wherein the first data stream originated from a first source and the second data stream originated from a second source, wherein the first source and the second source are different.

3. The method according to claim 1 wherein the first data stream and the second data stream originate from a common source which does not support multicasting.

4. The method according to claim 1 wherein the router is wireless.

5. The method according to claim 1 wherein the router is wired.

6. The method according to claim 1 wherein the step of multicasting the first data stream and the second data stream involves transmitting a data stream which has a higher quality value, wherein quality value is determined by buffering each data stream for a plurality of packets and measuring at least one of the following:

error rates and packet jitter.

7. The method according to claim 6 wherein the data stream which has the higher quality value has a lower delay between packets than other identical data streams being multicast.

8. The method according to claim 6 wherein the data stream which has the higher quality value has a lower delay variation between packets than other identical data streams being multicast.

9. The method according to claim 1 further comprising notifying the first client and the second client that data received is multicast.

10. The method according to claim 1 further comprising:

receiving a third data stream in replace of the first data stream; and

sending the first client the single multicast data stream and the third data stream.

11. The method according to claim 10 further comprising:

transmitting a signal to the first client indicating that the first client should ignore the single multicast data stream.

12. The method according to claim 10 further comprising:

after a predetermined period of time, unicasting the third data stream to the first client; and

unicasting the second data stream to the second client.

13. The method according to claim 1 further comprising:

detecting that a source of the first data stream has not transmitted any data streams for a predetermined period of time;

ceasing transmission of the single multicast data stream; and

unicasting the second data stream to the second client.

14. A method for comparing multiple data streams, wherein each data stream comprises a plurality of packets and each packet has a checksum, at a router comprising:

receiving a first data stream at a first time;

modifying each checksum in the first data stream to create a first plurality of modified checksum values;

storing the first plurality of modified checksum values for a window of time in a first memory;

receiving a second data stream at a second time;

modifying each checksum in the second data stream to create a second plurality of modified checksum values;

storing the second plurality of modified checksum values for a window of time in a second memory; and

comparing the first plurality of modified checksum values with the second plurality of modified checksum values to determine if the first data stream is identical to the second data stream.

15. The method according to claim 14 wherein the step of comparing further comprises offsetting in time the first plurality of modified checksum values with the second plurality of modified checksum values.

16. The method according to claim 14 wherein the step of comparing further comprises adding the first plurality of modified checksum values to the second plurality of modified checksum values, wherein if a result of adding the first plurality of modified checksum values with the second plurality of modified checksum values is 0xff then the first data stream is deemed identical to the second data stream, otherwise the first data stream is deemed different from the second data stream.

17. An apparatus for multicasting data streams comprising:

a network having a plurality of sources; and

a router coupled to the network operable to;

receive data streams from the plurality of sources; and

multicast identical data streams into a single multicast transmission for simultaneous receipt by multiple users, wherein the identical data streams multicast by the router originate from a common source which does not support multicasting.

18. The apparatus according to claim 17 wherein the router is wired.

19. The apparatus according to claim 17 wherein the router is wireless.

20. The apparatus according to claim 17 wherein the identical data streams multicast by the router originate from different sources.

21. An apparatus for comparing multiple data streams, wherein each data stream comprises a plurality of packets, at a router comprising:

a first memory for storing a modified checksum value for each packet received from a first data stream;

a second memory for storing a modified checksum value for each packet received from a second data stream; and

a processor, coupled to the first memory and to the second memory, programmed to compare the modified checksum values from the first data stream with the modified checksum values from the second data stream and add the modified checksum values from the first data stream with the modified checksum values of the second data stream to determine if the first data stream is identical to the second data stream.

22. The apparatus according to claim 21 wherein the processor is further operable to offset in time the modified checksum values of the first data stream with the modified checksum values of the second data