Method and apparatus for switching ATM, TDM, and packet data through a single communications switch while maintaining TDM timing

• US 6,631,130 B1
• Filed: 11/21/2000
• Issued: 10/07/2003
• Est. Priority Date: 11/21/2000
• Status: Expired due to Term

• Current Assignee: F Poszat Hu LLC (Intellectual Ventures LLC), Transwitch Corporation
• Original Assignee: Transwitch Corporation
• Inventors: Renault, Michael M., Roy, Subhash C., Upp, Daniel C., Lipp, William B., Benoit, Steven E.
• Primary Examiner(s): Vanderpuye, Kenneth
• Assistant Examiner(s): NGUYEN, BRIAN D
• Application Number:
  US09/717,440
• Time in Patent Office: 1,050 Days
• Field of Search: 370/352, 370/353, 370/390, 370/321, 370/337, 370/347, 370/395.1, 370/396, 370/398, 370/395.21, 370/395.42, 370/395.52, 370/401, 370/389, 370/392, 370/397, 370/395.4, 370/395.41, 370/400, 370/408, 370/437, 370/447, 370/462, 370/465, 370/468, 370/469, 370/498, 370/907, 359/135, 359/115
• US Class Current: 370/352
• CPC Class Codes: H04J 2203/0025 Peripheral units
• CPC Class Codes: H04J 2203/0026 Physical details
• CPC Class Codes: H04J 3/0682 by delay compensation, e.g. by compensation of propagation delay or variations thereof, by ranging
• CPC Class Codes: H04J 3/0688 Change of the master or reference, e.g. take-over or failure of the master
• CPC Class Codes: H04L 12/6402 Hybrid switching fabrics
• CPC Class Codes: H04L 2012/6413 Switch peripheries
• CPC Class Codes: H04L 7/10 Arrangements for initial synchronisation

Abstract

A network switch includes at least one port processor and at least one switch element. The port processor has an SONET OC-x interface (for TDM traffic), a UTOPIA interface (for ATM and packet traffic), and an interface to the switch element. In one embodiment, the port processor has a total I/O bandwidth equivalent to an OC-48, and the switch element has 12×12 ports for a total bandwidth of 30 Gbps. A typical switch includes multiple port processors and switch elements. A data frame of 9 rows by 1700 slots is used to transport ATM, TDM, and Packet data from a port processor through one or more switch elements to the same or another port processor. Each frame is transmitted in 125 microseconds; each row in 13.89 microseconds. Each slot includes a 4-bit tag plus a 4-byte payload. The slot bandwidth is 2.592 Mbps which is large enough to carry an E-1 signal with overhead. The 4-bit tag is a cross connect pointer which is setup when a TDM connection is provisioned. The last twenty slots of the frame are reserved for link overhead. Thus, the frame is capable of carrying the equivalent of 1,680 E-1 TDM signals. For ATM and packet data, a PDU (protocol data unit) of 16 slots is defined for a 64-byte payload. The PDUs are self-routed through the switch with a 28-bit routing tag which allows routing through seven switch stages using 4-bits per stage. Bandwidth is arbitrated among ATM and Packet connections while maintaining TDM timing.

Claims

1. A method for switching ATM, TDM, and packet data through a single communications switch, said method comprising:

a) generating a repeating data frame having a first plurality of rows, each row having a second plurality of slots;

b) pre-assigning some slots in every row of the frame for TDM data; and

c) assigning the remaining slots to ATM and packet data based on an arbitration technique, wherein

substantially all ATM and packet data is transmitted early in each row and substantially all TDM data is transmitted late in each row.

2. A method according to claim 1, further comprising:

d) extracting TDM data from a SONET frame at the ingress to the switch;

e) stripping off the V1-V4 bytes of the SONET frame at the ingress to the switch; and

f) regenerating V1-V4 bytes at the egress from the switch.

3. A method according to claim 1, wherein:

said step of generating a repeating data frame includes repeating the frame every 125 microseconds.

4. A method according to claim 1, wherein:

each slot has a bandwidth large enough to accommodate an E-1 signal or a DS1 signal.

5. A method according to claim 1, wherein:

said arbitration technique includes making a request during row N for slots in row N+1, where N is an integer.

6. A method according to claim 5, wherein:

the request is granted during row N.

7. A method according to claim 6, wherein:

the request includes hop-by-hop internal switch routing information and priority level information.

8. A method according to claim 6, wherein:

the request is granted out-of-band.

9. A method according to claim 1, wherein:

the frame includes 9 rows, each row containing 1700 slots.

10. A method according to claim 9, wherein:

each slot includes a four-byte payload.

11. A method according to claim 1, further comprising

d) defining a PDU (protocol data unit) as a fixed number of slots in one row;

e) assigning PDUs to ATM data and packet data based on an arbitration scheme.

12. A method according to claim 11, wherein:

each PDU accommodates a payload of 52 bytes.

13. A method according to claim 12, further comprising:

f) segmenting packets which are larger than 52 bytes into 52 byte chunks.

14. A method according to claim 12, wherein:

a PDU includes 16 slots.

15. A method according to claim 11, wherein:

said arbitration scheme includes making a request during row N for a PDU in row N+1, where N is an integer.

16. A method according to claim 11, further comprising:

f) extracting TDM data from a SONET frame at the ingress to the switch;

g) stripping off the V1-V4 bytes of the SONET frame at the ingress to the switch; and

h) regenerating V1-V4 bytes at the egress from the switch.

17. A method according to claim 11, wherein:

the arbitration scheme includes a method of multicasting PDUS.

18. An apparatus for switching ATM, TDM, and packet data through a single communications switch, said apparatus comprising:

a) means for generating a repeating data frame having a first plurality of rows, each row having a second plurality of slots;

b) means for pre-assigning some slots in every row of the frame for TDM data; and

c) means for assigning the remaining slots to ATM and packet data based on an arbitration technique, wherein

substantially all ATZM and packet data are transmitted early in each row and substantially all TDM data is transmitted late in each row.

19. An apparatus according to claim 18, further comprising:

d) means for extracting TDM data from a SONET frame at the ingress to the switch;

e) means for stripping off the V1-V4 bytes of the SONET frame at the ingress to the switch; and

f) means for regenerating V1-V4 bytes at the egress from the switch.

20. An apparatus according to claim 18, wherein:

said means for generating a repeating data frame includes means for repeating the frame every 125 microseconds.

21. An apparatus according to claim 18, wherein:

each slot has a bandwidth large enough to accommodate an E-1 signal or a DS1 signal.

22. An apparatus according to claim 18, wherein:

said arbitration technique includes making a request during row N for slots in row N+1, where N is an integer.

23. An apparatus according to claim 22, wherein:

the request is granted during row N.

24. An apparatus according to claim 23, wherein:

the request includes hop-by-hop internal switch routing information and priority level information.

25. An apparatus according to claim 23, wherein:

the request is granted out-of-band.

26. An apparatus according to claim 18, wherein:

the frame includes 9 rows, each row containing 1700 slots.

27. An apparatus according to claim 26, wherein:

each slot includes a four-byte payload.

28. An apparatus according to claim 18, further comprising

d) means for defining a PDU (protocol data unit) as a fixed number of slots in one row;

and

e) means for assigning PDUs to ATM data and packet data based on an arbitration scheme.

29. An apparatus according to claim 28, wherein:

each PDU accommodates a payload of 52 bytes.

30. An apparatus according to claim 29, further comprising:

f) means for segmenting packets which are larger than 52 bytes into 52 byte chunks.

31. An apparatus according to claim 29, wherein:

a PDU includes 16 slots.

32. An apparatus according to claim 28, wherein:

said arbitration scheme includes making a request during row N for a PDU in row N+1, where N is an integer.

33. An apparatus according to claim 28, further comprising:

f) means for extracting TDM data from a SONET frame at the ingress to the switch;

g) means for stripping off the V1-V4 bytes of the SONET frame at the ingress to the switch; and

h) means for regenerating V1-V4 bytes at the egress from the switch.

34. An apparatus according to claim 28, wherein:

the arbitration scheme includes a method of multicasting PDUs.