FORWARD ERROR CORRECTION BASED DATA RECOVERY WITH PATH DIVERSITY

• US 20090201805A1
• Filed: 04/11/2008
• Published: 08/13/2009
• Est. Priority Date: 02/10/2008
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Oran, David, Begen, Ali
• Granted Patent: US 8,787,153 B2
• Time in Patent Office: Days
• US Class Current: 370/225
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0014 by adapting the source coding
• CPC Class Codes: H04L 1/0018 based on latency requirement
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 1/06 using space diversity
• CPC Class Codes: H04L 1/22 using redundant apparatus to increase reliability
• CPC Class Codes: H04L 69/14 Multichannel or multilink protocols

Abstract

A media source sends media packets over a first media path. Repair packets are encoded from the media source packets and sent over a second different media path. Sending the source packets and repair packet over different media paths is referred to as Forward Error Correction (FEC) spatial diversity and reduces the amount of repair packet overhead required for repairing the media source packets in case of a network outage or packet loss. To provide load balancing, a first set of media streams may be sent over the first media path and a second set of media streams may be sent over the second media path. If a fault is detected on one of the media paths, then the repair packets may no longer be transmitted and the one or more media streams from the disabled media path are transmitted over the working media path.

Claims

1. An apparatus, comprising:

one or more network devices configured to send source packets over a first link or device media path, the one or more network devices further configured to encode repair packets from the source packets and send the repair packets over a second different link or device media path.

2. The apparatus according to claim 1 further comprising determining a latency budget X and configuring the one or more network devices to send source blocks of source packets having a duration approximately equal to the latency budget X.

3. The apparatus according to claim 2 further comprising determining a maximum outage duration Q and configuring the one or more network devices to encode and send repair blocks of repair packets on the second link or device media path large enough to repair the media packets for the maximum outage duration Q.

4. The apparatus according to claim 3 wherein the outage duration Q can be comparable or equal to the latency budget X.

5. The apparatus according to claim 3 wherein:

the duration of the source block is approximately equal to the latency budget X;

the duration of the repair block is approximately equal to the maximum outage duration Q; and

a bandwidth overhead for sending the repair block is approximately equal to Q/X.

6. The apparatus according to claim 1 wherein the one or more network devices are further configured to:

send a first set of media streams over the first link or device media path;

second a second set of media streams over the second link or device media path;

encode a first group of repair packets for the first set of media streams and send the first group of repair packets over the second link or device media path; and

encode a second group of repair packets for the second set of media streams and send the second group of repair packets over the first link or device media path.

7. The apparatus according to claim 6 wherein the one or more network devices are further configured to:

detect a failure on the first link or device media path;

stop sending the second group of repair packets on the second link or device media path; and

start sending the first set of media streams on the second link or device media path.

8. The apparatus according to claim 1 wherein the one or more network devices are further configured to:

detect a failure on the first link or device media path;

stop sending the repair packets on the second link or device media path when the failure is detected on the first link or device media path; and

redirect the source packets from the first link or device media path to the second link or device media path.

9. The apparatus according to claim 8 wherein the first link or device media path is established over a first type of access network and the second link or device media path is established over another different type of access network.

10. The apparatus according to claim 1 wherein the source packets and repair packets are multicast over the first and second link or device media path.

11. The apparatus according to claim 1 wherein the source packets and repair packets are unicast over the first and second link or device media path.

12. A method, comprising:

generating Forward Error Correction (FEC) packets from media for repairing the source packets;

transmitting the source packets on a first network path or link to one or more network devices; and

transmitting the FEC packets on a second different network path or link to the same one or more network devices.

13. The method according to claim 12 wherein the first and second network path or link may be either different logical links or different network device paths.

14. The method according to claim 12 further comprising:

detecting a network failure on the first network path or link;

discontinuing transmission of the FEC packets on the second network path or link; and

redirecting the transmission of the source packets over the second network path or link.

15. The method according to claim 12 further comprising:

determining a latency budget duration X;

determining an outage duration Q;

generating source blocks of source packets proportional to the latency budget duration X;

sending the source blocks of source packets over the first network path or link;

generating repair blocks of FEC packets proportional to the outage duration Q; and

sending the repair blocks of FEC packets over the second network path or link.

16. The method according to claim 15 further comprising adaptively changing the value of Q based on empirical data, administrative policies, or an importance of the media in the source packets.

17. The method according to claim 15 further comprising dynamically changing the value of X based on empirical data, administrative policies, or an importance of the media in the source packets.

18. The method according to claim 15 wherein the duration of the source blocks and the duration of the repair blocks have an associated repair overhead of approximately Q/X.

19. The method according to claim 15 wherein the outage duration Q is comparable or equal to the latency budget X.

20. The method according to claim 12 further comprising:

using a first Internet Protocol (IP) destination address or MPLS label in the source packets associated with the first network path or link; and

using a second IP destination address or MPLS label in the FEC packets associated with the second network path or link.

21. The method according to claim 12 further comprising:

sending a first set of media streams over the first network path or link;

sending a second set of media streams over the second network path or link;

sending a first set of FEC packets for the first set of media streams over the second network path or link; and

sending a second set of FEC packets for the second set of media streams over the first network path or link.

22. An apparatus, comprising:

a receiving network device configured to receive one or more media streams from a transmitting network over a first network path or link, the receiving network device further configured to receive Forward Error Correction (FEC) packets over a second network path or link for repairing the one or more media streams received from the transmitting network device over the first network path or link.

23. The apparatus according to claim 22 wherein the media streams are load balanced over the first and second network path or link with a first set of media streams being received over the first network path or link, a second set of media streams being received over the second network path or link, a first set of FEC packets for the first set of media streams being received over the second network path or link, and a second set of FEC packets for the second set of media streams being received over the first network path or link.

24. The apparatus according to claim 23 wherein the receiving network device is further configured to:

receive the first set of media streams over the first network path or link and receive the second set of media streams over the second network path or link until a fault is detected on the first or second network path or link; and

receive both the first set of media steams and the second set of media streams over the first or second network path that does not have the detected fault; and

no longer receive any FEC packets on the first or second network path or link that has the detected fault.

25. The apparatus according to claim 23 further comprising:

receiving the one or more media streams on the first network path or link from the transmitting network device until a fault is detected on the first network path or link; and

no longer receiving the FEC packets from the transmitting network device on the second network path or link when the fault is detected on the first network path or link; and

receiving the one or more media streams previously received on the first network path or link from the transmitting network device on the second network path or link.