System and method for the synchronization and distribution of telephony timing information in a cable modem network

• US 6,819,682 B1
• Filed: 09/06/2000
• Issued: 11/16/2004
• Est. Priority Date: 09/03/1999
• Status: Expired due to Term

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Denney, Lisa V., Rabenko, Theodore F.
• Primary Examiner(s): HO, DUC CHI
• Application Number:
  US09/656,459
• Time in Patent Office: 1,532 Days
• Field of Search: H04/J.306, H04/L 1.228, H04/L 1.256, H04/L 1.266, H04/L.700, 370/503, 370/508, 370/509, 370/352, 370/401, 370/357, 375/327, 375/354, 375/356, 375/359, 375/222, 714/111, 714/64, 379/167.11
• US Class Current: 370/503
• CPC Class Codes: H04J 3/0644 External master-clock
• CPC Class Codes: H04J 3/0664 unidirectional timestamps
• CPC Class Codes: H04J 3/0673 using intermediate nodes, e.g. modification of a received timestamp before further transmission to the next packet node, e.g. including internal delay time or residence time into the packet

Abstract

A method for synchronizing clocks in a packet transport network. The method comprises, receiving an external network clock at a central packet network node and transmitting timing information to a plurality of packet network devices, the timing information based upon the external network clock. The method further comprises, transmitting and receiving data that is synchronized to the timing information to a plurality of connected packet network devices. And finally, delivery of packets to an external interface via a packet network that contains data synchronized to the external network clock.

Claims

1. A communications system, comprising:

a cable modem termination system coupled to a plurality of networks at a back side of the cable modem termination system;

a clock external to the cable modem termination system, the cable modem termination system and the plurality of networks being synchronized to the external clock wherein the external clock being synchronized to a public switched network and

a cable modem coupled to the cable modem termination system at a front side of the cable modem termination system.

2. The communications system of claim 1 further comprising a telephone coupled to the cable modem.

3. The communications system of claim 1 wherein the cable modem is synchronized to the cable modem termination system.

4. The communications system of claim 1 further comprising a network coupled to the cable modem.

5. The communications system of claim 4 wherein the network comprises an in-home twisted pair telephone line.

6. The communications system of claim 5, wherein the network further comprises a telephone coupled to the in-home twisted pair telephone line.

7. The communications system of claim 5 wherein the cable modem is synchronized to the cable modem termination system.

8. The communications system of claim 1 wherein the external clock comprises a station reference for a public switched telephone network.

9. The communications system of claim 8 wherein the cable modem termination system further comprises a local reference clock synchronized to the station reference, the cable modem termination system being synchronized to the local reference clock.

10. The communications system of claim 9 wherein the local reference clock comprises a Stratum 3 reference clock.

11. The communications system of claim 2 further comprising a gateway between the public switched telephone network and the cable modem termination system, the gateway being synchronized to the external clock.

12. The communications system of claim 2 wherein at least one of the plurality of the networks comprises an Ethernet.

13. The communications system of claim 12 wherein the external clock comprises a station reference.

14. The communications system of claim 13 wherein the cable modem termination system further comprises a local reference clock synchronized to the station reference, the cable modem termination system being synchronized to the local reference clock.

15. The communications system of claim 14 wherein the local reference clock comprises a Stratum 3 reference clock.

16. The communications system of claim 15 further comprises a second network coupled to the cable modem.

17. The communications system of claim 16 wherein the second network comprises an in-home twisted pair telephone line.

18. The communications system of claim 17 wherein the cable modem is synchronized to the cable modem termination system.

19. The communications system of claim 17 wherein the second network is synchronized to the cable modem.

20. A method of communications, comprising:

synchronizing a cable modem termination system and a plurality of networks coupled to one side of the cable modem termination system to a clock external to the cable modem termination system wherein the external clock being synchronized to a public switched network and

exchanging data or voice between the cable modem termination system and a cable modem coupled to another side of the cable modem termination system.

21. The method of claim 20 further comprising synchronizing the cable modem to the cable modem termination system.

22. The method of claim 20 further comprising exchanging the data or voice between the cable modem and a network.

23. The method of claim 22 wherein the network comprises an in-home twisted pair telephone line.

24. The method of claim 23 further comprising synchronizing the cable modem to the cable modem termination system.

25. The method of claim 20 wherein the external clock comprises a station reference synchronized by a public switched telephone network.

26. The method of claim 25 wherein the cable modem termination system synchronization comprises synchronizing a local reference clock to the station reference, and synchronizing the cable modem termination system to the local reference clock.

27. The method of claim 26 wherein the local reference clock comprises a Stratum 3 reference clock.

28. The method of claim 24 further comprising exchanging the data or voice between the public switched telephone network and the cable modem termination system.

29. The method of claim 28 wherein the external clock comprises a station reference.

30. The method of claim 29 wherein the cable modem termination system synchronization comprises synchronizing a local reference clock to the station reference, and synchronizing the cable modem termination system to the local reference clock.

31. The method of claim 30 wherein the local reference clock comprises a Stratum 3 reference clock.

32. The method of claim 31 further comprising exchanging the data or voice between the cable modem and network.

33. The method of claim 32 wherein the network comprises an in-home twisted pair telephone line.

34. The method of claim 33 further comprising synchronizing the cable modem to the cable modem termination system.

35. The method of claim 34 wherein the network comprises a device, the method further comprising synchronizing the device to the cable modem.

36. The method of claim 35 further comprising synchronizing the external clock to a public switched telephone network.

37. The method of claim 36 further comprising exchanging the data or voice between the public switched telephone network and the gateway.

38. The method of claim 37 wherein the external clock comprises a station reference.

39. The method of claim 38 wherein the cable modem termination system synchronization comprises synchronizing a local reference clock to the station reference, and synchronizing the cable modem termination system to the local reference clock.

40. The method of claim 39 wherein the local reference clock comprises a Stratum 3 reference clock.

41. The method of claim 40 further comprising exchanging the data or voice between the cable modem and a network.

42. The method of claim 41 wherein the network comprises an in-home twisted pair telephone line.

43. The method of claim 42 further comprising synchronizing the cable modem to the cable modem termination system.

44. The method of claim 43 wherein the

network comprises a device, the method further comprising

synchronizing the network to the cable modem.

45. The method of claim 20 further comprising synchronizing a gateway to the external clock, and exchanging the voice or data between the gateway and the cable modem termination system.

46. A communications system comprising:

a cable modem termination system;

a clock external to the cable modem termination system, the cable modem termination system being synchronized to the external clock wherein the external clock being synchronized to a public switched network

a cable modem coupled to the cable modem termination system; and

a network coupled to the cable modem including an in-home twisted pair telephone line,

wherein the network further comprises a device coupled to the in-home twisted pair telephone line and synchronized to the cable modem.

47. A method of communications, comprising:

synchronizing a cable modem termination system to a clock wherein the external clock being synchronized to a public switched network external to the cable modem termination system;

exchanging data or voice between the cable modem termination system and a cable modem

exchanging the data or voice between the cable modem and a network comprising an in-home twisted pair telephone line; and

synchronizing the cable modem to the cable modem termination system,

wherein the network comprises a device, the method further comprising synchronizing the device to the cable modem.