TDM over IP (IP circuit emulation service)

• US 6,731,649 B1
• Filed: 07/26/2000
• Issued: 05/04/2004
• Est. Priority Date: 07/26/2000
• Status: Expired due to Term

• Current Assignee: Rad Data Communications Limited (Zisapel Family)
• Original Assignee: Rad Data Communications Limited (Zisapel Family)
• Inventors: Silverman, Hugo
• Primary Examiner(s): VANDERPUYE, KENNETH N
• Application Number:
  US09/626,335
• Time in Patent Office: 1,378 Days
• Field of Search: 370/466, 370/395.1, 370/401, 370/474, 370/352, 370/353, 370/395.52, 370/395.5
• US Class Current: 370/466
• CPC Class Codes: H04L 2012/5654 using the AAL1
• CPC Class Codes: H04L 2012/5663 Support of N-ISDN
• CPC Class Codes: H04L 2012/5667 IP over ATM
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

A method and system for processing one or more TDMs for communication over IP networks, such as the Internet, includes encapsulating ATM cells (packets) using AAL1 cells within UDP over IP frames to provide synchronous bit streams into fixed size cells. This allows for an IP header to be added to the packets, with such packets forwarded to its destination host across the IP network. The destination regenerates the clock, decrypts/strips the IP header and delivers a synchronous bit stream. Furthermore, an adaptive clock is provided for clock transfer across the network. The adaptive clock regenerates the far end T1/E1 receive clock out of the incoming arrival frame rate. Frames arriving from the IP network are stored in a buffer and taken out for TDM stream assembly.

Claims

1. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), said system comprising:

an IP network;

a TDM source stream;

decoder to decode said TDM source stream;

a converter to convert one or more parts of said decoded TDM source stream into a circuit emulation service(CES) structure;

a segmenter to partition said converted one or more parts and remove cell header(s);

packetizer receiving output from said segmenter and packetizing thereof, and

wherein packets output from said packetizer are an IP compatible format suitable for transfer over said IP network.

2. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 1, wherein said TDM source stream comprises a E1/T1 TDM stream.

3. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 2, wherein said decoded E1/T1 TDM stream is delivered over a PCM bus.

4. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 3, wherein said circuit emulation service conforms to ATM forum specification AF-VTOA-0078 (1997), known as CES 2.0.

5. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 1, wherein said circuit emulation service(CES) structure comprises any of three types:

unstructured, structured or structured with CAS.

6. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 1, wherein said segmenter partitions into cells.

7. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 6, wherein said partitioning reflects the ITU-T 363.1 standard.

8. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 1, wherein said output from said segmenter comprises AAL1 headers and payload.

9. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 1, wherein said packetizer packets the cells into UDP over IP frames adding connection information into the UDP header.

10. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 9, wherein said connection information includes at least a destination IP specifying a remote device and addressing specifying a destination E1/T1 port and bundle which is a group of time slots.

11. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 1, wherein said system further comprises a receiving section acquiring packets output from said packetizer and transferred across said IP network.

12. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 11, wherein said receiving section comprises:

a cell extractor to strip the cells from said UDP payload;

a reassembler to restructure said stripped cells according to circuit emulation service(CES) standards;

a packet delay variation buffer to compensate for network delay variation;

a framer and encoder, and

wherein output from said framer and encoder is transmitted as a TDM stream.

13. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 1, wherein said system further comprises an adaptive clock.

14. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 12, wherein said system further comprises an adaptive clock used to regenerate a E1/T1 receive clock.

15. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 14, wherein said adaptive clock comprises a monitored fill buffer and PLL.

16. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 15, wherein when said monitored fill buffer is filling up, the regenerated clock rate will be increased and when said monitored fill buffer is emptying, the regenerated clock rate will be decreased.

17. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 1, wherein said system is implemented across networks comprising any of LANs, WANs, cellular, Internet or Web based networks.

18. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), comprising the following steps for TDM up and down stream link port flow:

A. said down link flow of said TDM stream comprising the steps;

(1) receiving one or more TDM signals;

(2) decoding said received one or more TDM signals from line and frame alignment;

(3) building structures according to circuit emulation service(CES) standards;

(4) segmenting said structures into ATM cells;

(5) stripping the ATM header;

(6) packetizing the stripped cells into UDP over IP Ethernet frames, and

(7) transmitting said packetized cells over IP networks;

B. said up link flow of said TDM stream uplink port comprising the steps;

(1) receiving Ethernet frames from said IP network;

(2) stripping the ATM cells from a UDP payload;

(3) reassembling said stripped cells according to circuit emulation service(CES) standards;

(4) compensating for network delay variations;

(5) framing said reassembled cells;

(6) encoding said framed output;

(7) transmitting said encoded output over TDM lines.

19. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 18, wherein said TDM signals comprises a E1/T1 TDM stream.

20. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 19, wherein said decoded E1/T1 TDM signals is delivered over a PCM bus.

21. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 18, wherein said circuit emulation service conforms to ATM forum specification AF-VTOA-0078 (1997), known as CES 2.0.

22. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 18, wherein said circuit emulation service(CES) structure comprises any of three types:

unstructured, structured or structured with CAS.

23. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 18, wherein said segmenting said structures into ATM cells reflects the ITU-T 363.1 standard.

24. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 18, wherein the output from segmenting said structures into ATM cells comprises AAL1 headers and payload.

25. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 18, wherein said packetizing step packets the cells into UDP over IP frames adding connection information into a UDP header.

26. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 25, wherein said connection information includes at least a destination IP specifying a remote device and addressing specifying a destination E1/T1 port and bundle which is a group of time slots.

27. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 1, wherein said compensation step is implemented with an adaptive clock.

28. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 27, wherein said adaptive clock is used to regenerate a E1/T1 receive clock.

29. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 28, wherein said adaptive clock comprises a monitored fill buffer and PLL.

30. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 29, wherein when said monitored fill buffer is filling up, the regenerated clock rate is increased and when said monitored fill buffer is emptying, the regenerated clock rate is decreased.

31. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 18, wherein said compensation step is implemented by the following steps:

(1) loading a buffer with TDM bytes extracted from arriving frames;

(2) emptying said buffer after reaching at least a half filled state according to a rate set by a transmission clock;

(3) generating a fill indication;

(4) comparing the fill indication to a nominal fill level;

(5) filtering said output to produce an adaptive clock, and

(6) recursively using said adaptive clock as said transmission clock in step (2).

32. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 31, wherein step (2) is implemented with a PLL.

33. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 18, wherein said method is implemented across networks comprising any of LANs, WANs, cellular, Internet or Web based networks.

34. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), comprising the following:

receiving one or more TDM signals;

decoding said received one or more TDM signals;

building ATM CES structures using AAL1 cells without a cell header;

encapsulating said ATM CES structures into UDP over IP frames, and

transmitting said UDP over IP frames over UP networks.

35. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 34, further comprising specifying a destination of the AAL1 cells termination Interworking function.

36. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 35, wherein said specifying step utilizes a UDP source port field.

37. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 34, further comprising the step of compensating for network delays.

38. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 37, wherein said compensation step is implemented by the following steps:

(1) loading a buffer with TDM bytes extracted from arriving frames;

(2) emptying said buffer after reaching at least a half filled state according to a rate set by a transmission clock;

(3) generating a fill indication;

(4) comparing the fill indication to a nominal fill level;

(5) filtering said output to produce an adaptive clock, and

(6) substituting said adaptive clock as said transmission clock in step (2).

39. A computer based communications system implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 1, wherein said system implements voice over IP (VoIP).

40. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 18, wherein said method implements voice over IP (VoIP).

41. A computer based method implementing TDM over an Internet Protocol network (TDM over IP, TDMoIP), as per claim 37, wherein said method implements voice over IP (VoIP).