Granted Patent B1

US 7,535,893 · App. 10/728,466 · Granted May 19, 2009

Abstract

Claims (29)

1. A method for operating a switching node, comprising:

maintaining a packet-switched fabric that switches both time-division multiplexed (TDM) traffic and packet-based protocol data unit (PDU) traffic on the same fabric with packet switching;

overlaying the packet-switching of the fabric with a repeating synchronized frame, the frame to allocate timeslots for switching the TDM traffic and the PDU traffic over the packet-switched fabric, including

maintaining a timeslot-reservation table for TDM traffic, the table having a row of entries, each entry corresponding to a timeslot of the frame;

prescheduling switching of the fabric for TDM traffic by populating the entries in the table according to a contention-free allocation to provide exclusive reservation of timeslots in the frame for cells of TDM traffic to provide deterministic switching of TDM traffic over the fabric based on the prescheduling of the frame; and

scheduling switching of the fabric for PDU traffic by arbitration scheduling of available timeslots in the frame; and

switching both the TDM traffic and the PDU traffic over the packet-switched fabric traffic in accordance with the repeating synchronized frame, including transmitting a cell on a timeslot in accordance with the populated table.

2. A method according to claim 1 , wherein overlaying the packet-switching of the fabric with the synchronized frame further comprises providing a contention-free allocation in time and space of TDM traffic using a Slepian-Duguid-based algorithm.

3. A method according to claim 1 , wherein maintaining the table comprises maintaining the table with a central management that manages tables of multiple switch interface devices in a system.

4. A method according to claim 1 , further comprising providing a synchronization signal to demark the frame.

5. A method according to claim 1 , wherein overlaying the packet-switching of the fabric with the synchronized frame further comprises providing distributed switching of TDM traffic from multiple sources of TDM traffic over the fabric.

6. A method according to claim 1 , wherein populating the table comprises populating a TDM timeslot reservation table, and further comprising:

preventing PDU traffic from being transmitted on a timeslot that is reserved for TDM traffic;

determining whether an egress device has bandwidth that is not reserved for TDM traffic by TDM timeslot reservations; and

transmitting PDU traffic to the egress device if the egress device has available bandwidth that does not contend with the TDM traffic reservations as a result of the determination.

7. A method according to claim 1 , the packet-switched fabric having a Clos network configuration.

8. A switching system comprising:

a packet-switched switching fabric that switches both time-division multiplexed (TDM) traffic and packet-based protocol data unit (PDU) traffic on the same fabric with packet switching;

multiple switch interfaces having a timeslot-reservation table for TDM traffic, the table having a row of entries, each entry corresponding with a timeslot on a frame, the frame to allocate timeslots for switching the TDM traffic and the PDU traffic to preschedule switching of the fabric for TDM traffic by populating the entries in the table according to a contention-free allocation to provide exclusive reservation of timeslots in the frame for cells of TDM traffic to provide deterministic switching of TDM traffic over the fabric based on the prescheduling of the frame, and the frame to further schedule switching of the fabric for PDU traffic by arbitration scheduling of available timeslots in the frame, the multiple switch interfaces to transmit cells of traffic in accordance with the entries in the table; and

a switch management circuit to define the frame and synchronize switching of traffic over the fabric that switches both the TDM traffic and the PDU traffic in accordance with the frame.

9. A system according to claim 8 , wherein the switch management circuit provides modifications of the table to the multiple switch interfaces.

10. A system according to claim 8 , wherein the switch management circuit to synchronize the switching of traffic over the fabric further comprises the switch management circuit to provide a synchronization signal to the switch fabric and the multiple switch interfaces to demark the frame.

11. A system according to claim 8 , wherein the multiple switch interfaces are directly inter-connectable for system input to system output via the timeslots on the frame synchronized by the switch management circuit.

12. A system according to claim 8 , wherein the packet-switched switching fabric further prevents PDU traffic from being transmitted on a timeslot that is reserved for TDM traffic, determines whether an egress device has bandwidth that is not reserved for TDM traffic by TDM timeslot reservations, and transmits PDU traffic to the egress device if it is determined that the egress device has available bandwidth that does not contend with the TDM traffic reservations.

13. A system according to claim 8 , wherein the switch fabric comprises multiple discrete switching circuits.

14. A system according to claim 8 , wherein the multiple switch interfaces comprise multiple ingress/egress linecards.

15. A system according to claim 8 , wherein the switch management circuit comprises a switch management linecard having a circuit to generate a synchronization signal and a circuit to provide management of the table.

16. A system according to claim 8 , the packet-switched switching fabric having a Clos network configuration.

17. A system according to claim 8 , wherein the contention-free allocation in time and space is generated using a Slepian-Duguid-based algorithm.

Assignments (8)