Telecommunications switch with improved redundancy

• US 5,596,569 A
• Filed: 10/10/1995
• Issued: 01/21/1997
• Est. Priority Date: 03/08/1994
• Status: Expired due to Term

• Current Assignee: Excel Switching Corp. (Enghouse Systems Limited)
• Original Assignee: Excel Incorporated
• Inventors: Eschholz, Siegmar K., Lynch, John T., Madonna, Robert P.
• Primary Examiner(s): HSU, ALPUS
• Application Number:
  US08/590,688
• Time in Patent Office: 469 Days
• Field of Search: 370/13, 370/14, 370/16, 370/54, 370/58, 370/1, 370/58.2, 370/58.3, 370/85.1, 370/85.7, 370/85.8, 370/85.9, 370/85.11, 370/95.1, 370/95.2, 340/825.03, 340/826, 340/827, 340/825.06, 340/825.08, 340/825.79, 340/825.8, 340/825.83, 379/268, 379/271, 379/272, 379/273, 379/279, 379/291, 379/333, 379/335, 395/180, 395/181, 395/182.01, 395/182.02, 395/183.16, 395/183.17, 395/183.19
• US Class Current: 370/217
• CPC Class Codes: G06F 13/4063 Device-to-bus coupling
• CPC Class Codes: H04J 3/14 Monitoring arrangements for SDH/SONET rings H04J3/085
• CPC Class Codes: H04J 3/1623 Plesiochronous digital hierarchy [PDH]
• CPC Class Codes: H04M 3/12 Marking faulty circuits "busy"; Enabling equipment to disengage itself from faulty circuits ; Using redundant circuits; Response of a circuit, apparatus or system to an error
• CPC Class Codes: H04M 7/0096 Trunk circuits
• CPC Class Codes: H04Q 11/04 for time-division multiplexing H04Q11/0001 takes precedence
• CPC Class Codes: H04Q 11/0414 Details
• CPC Class Codes: H04Q 2201/12 Printed circuits
• CPC Class Codes: H04Q 2213/13003 Constructional details of switching devices
• CPC Class Codes: H04Q 2213/13031 Pulse code modulation, PCM
• CPC Class Codes: H04Q 2213/1308 Power supply
• CPC Class Codes: H04Q 2213/13106 Microprocessor, CPU
• CPC Class Codes: H04Q 2213/13107 Control equipment for a part of the connection, distributed control, co-processing
• CPC Class Codes: H04Q 2213/13292 Time division multiplexing, TDM
• CPC Class Codes: H04Q 2213/13299 Bus
• CPC Class Codes: H04Q 2213/13396 Signaling in general, in-band signalling
• CPC Class Codes: H04Q 3/625 Arrangements in the private branch exchange

Abstract

A programmable telecommunications switch has automatic backup of line cards to provide complete redundancy. The switch has I/O cards which terminate the external telecommunications spans. Each I/O card passes the data from its spans to a line card. When the line card fails, the I/O card switches the data onto an I/O bus which is connected to a standby I/O card. The standby I/O card switches a standby line card into connection with the I/O bus such that the data stream is then serviced by the standby line card. The failed line card may then be removed and replaced. All I/O cards are attached to the I/O bus such that redundancy for all active line cards using the same signalling protocol is provided with a single standby line card. With multiple I/O busses, standby I/O cards and standby line cards, multiple redundancy is possible. Finally, the failure of a single line module of a line card may be handled by switching only the span serviced by that module to a standby line card. Spans from different I/O cards may be serviced by different line modules of a single standby line card, and may be all connected to the same standby line card by the same bus.

Claims

1. A programmable telecommunications switch comprising:

a switching matrix for dynamically connecting and disconnecting communications paths between a plurality of communication channels;

a first line module configured to receive at least one telecommunications signal of a certain protocol type and transmit the telecommunications signal to a first communication channel of the plurality of communications channels of the switching matrix, wherein the first line module is independently instructable to transmit to any one of the plurality of communication channels;

a second line module configured to receive at least one telecommunications signal of said certain protocol, wherein the second line module is independently instructable to transmit a received telecommunications signal to any one of the plurality of communication channels;

an active input device configured to terminate an external span having at least one conductor carrying at least one telecommunications signal of said certain protocol type, the active input device having a plurality of connection modes, a first mode being such that the span is connected in a communicating relationship to the first line module and a second mode being such that the span is connected in a communicating relationship to the second line module, the active input device changing from the first mode to the second mode in response to a changeover signal; and

a data processor configured to respond to a malfunction of the first line module by instructing the second line module to transmit received telecommunications signals to the first communication channel and generating the changeover signal, thereby causing the first line module to be functionally replaced by the second line module.

2. A switch according to claim 1 wherein the first fine module is located on a printed circuit board adapted to be physically inserted and removed from the switch.

3. A switch according to claim 2 wherein the printed circuit board further comprises an edge connector configured to enable the first line module to make an electrical connection with the data processor and the active input device.

4. A switch according to claim 2 further comprising:

a main power source from which the switching matrix, the first line module, the second line module, the active input device and the data processor all receive electrical power; and

a pre-charge power source which, upon insertion of the circuit board, provides power to the first line module before the first line module receives power from the main power source.

5. A switch according to claim 1 further comprising:

a standby input device coupled to and associated with the second line module;

an input/output (I/O) bus configured to couple the standby input device with the active input device;

whereby the standby input device has a plurality of connection modes, a first mode of the standby input device connecting the I/O bus to the second line module and a second mode of the standby input device disconnecting the I/O bus from the second line module, the standby input device changing from the first mode to the second mode in response to a standby signal generated by the data processor.

6. A switch according to claim 5 wherein the first line module is part of a first line card having a plurality of line modules and the second line module is part of a second line card having a plurality of line modules.

7. A switch according to claim 5 wherein the standby input device is a first standby input device and the standby signal is a first standby signal, and wherein the switch comprises a plurality of the first and second line modules and a plurality of standby input devices, each standby input device connecting an associated second line module to the I/O bus in a first connection mode and disconnecting the associated second line module from the I/O bus in a second connection mode, the changing of each standby input device from its first mode to its second mode being in response to one of a plurality of distinct standby signals generated by the data processor.

8. A switch according to claim 7 wherein the active input device is one of a plurality of active input devices each terminating a span carrying a telecommunications signal and wherein the different line modules are grouped together on line cards such that each of the line modules on a single line card services a different external span.

9. A switch according to claim 7 wherein the active input device is one of a plurality of active input devices each terminating a span carrying a telecommunications signal and wherein the plurality of line modules includes line modules servicing telecommunication signals using different signaling protocols.

10. A switch according to claim 1 wherein the data processor is a microprocessor.

11. A programmable telecommunications switch comprising:

a switching matrix for dynamically connecting and disconnecting communications paths between a plurality of communication channels;

a first line card configured to receive telecommunications signals and transmit the telecommunications signals to predetermined ones of said plurality of communication channels of the switching matrix, wherein the first line card is independently instructable to transmit to any of the plurality of communication channels;

a second line card configured to receive said telecommunications signals and further configured to be independently instructable to transmit the telecommunications signals to predetermined ones of said plurality of communication channels of the switching matrix

an input/output I/O bus configured to carry telecommunications signals;

an active I/O card, coupled to and associated with the first line card, configured to terminate a plurality of external spans carrying telecommunications signals and which has a plurality of connection modes, a first mode connecting the external spans in a communicating relationship to the first line card and a second mode connecting the spans in a communicating relationship to the I/O bus, the active I/O card changing from one mode to the other in response to a changeover signal;

a standby I/O card having a plurality of connection modes, a first connection mode connecting the second line card in a communicating relationship to the I/O bus, and a second mode disconnecting the second line card from the I/O bus, the standby I/O card changing from one mode to another in response to a standby signal; and

a data processor configured to instruct the second line card to transmit said received telecommunications signals to the same predetermined one of said communication channels previously used by the first line card and to generate the changeover signal and the standby signal to functionally replace the first line card with the second line card.

12. A switch according to claim 11 wherein, when the active I/O card is in the second mode and the standby I/O card is in the first mode, the first line card can be removed from the switch without disrupting the operation of the switch.

13. A programmable telecommunications switch comprising:

a switching matrix for dynamically connecting and disconnecting communications paths between a plurality of communication channels;

a plurality of independently instructable and functionally compatible line cards, coupled to the switching matrix, each of the plurality of line cards configured to receive at least one telecommunications signal and transmit the received telecommunications signal to one or more of the plurality of communication channels of the switching matrix, each line card further configured to transmit the received telecommunications signal to one or more of the plurality of communication channels of the switch in accordance with an externally generated instruction;

a plurality of active input/output I/O cards each of which terminates a plurality of external spans carrying telecommunications signals and each of which has a plurality of connection modes including a first mode in which the spans are connected in communicating relationship with an associated one of said plurality of line cards, the mode of each active I/O card being changeable in response to one of a plurality of distinct changeover signals each specific to a different active I/O card;

a plurality of I/O busses arranged such that each active I/O card connects the spans it terminates to a different one of said I/O busses for each of its connection modes other than the first mode;

a plurality of standby I/O cards each having a plurality of connection modes and being arranged such that different connection modes of a standby I/O card correspond to a line card by that standby I/O card being connected to a different one of the I/O busses, the connection mode of each standby I/O card being changeable in response to one of a plurality of distinct standby signals each specific to a different standby I/O card; and

a data processor, responsive to a malfunctioning line card transmitting the telecommunications signal to a first communication channel of the switch matrix configured to generate an instruction signal to an operational one of the plurality of line cards to transmit the telecommunications signal to the same communication channels of the switch matrix previously used by the malfunctioning card, and to generate a particular one of the changeover signals and a particular one of the standby signals to functionally replace the malfunctioning line card with the operational line card.

14. A switch according to claim 13 wherein the particular standby signal causes a designated standby I/O card to connect the operational line card associated with such standby I/O card to a designated I/O bus, and the particular changeover signal causes an active I/O card which is associated with the malfunctioning line card to connect the spans terminated on such active I/O card to said designated I/O bus.

15. A programmable telecommunications switch having a switching matrix for dynamically connecting and disconnecting communication paths between a plurality of communication channels, a first line module arranged to receive at least one telecommunications signal and transmit the telecommunications signal to the switching matrix, and a second line module arranged to receive at least one telecommunications signal and transmit the telecommunications signal to the switching matrix, each of the line modules being functionally compatible and independently instructable to transmit a received telecommunications signal to any one of the plurality of communication channels, the switch comprising:

an input device configured to terminate an external span having at least one conductor carrying at least one telecommunications signal, the input device having a plurality of connection modes, a first mode being such that the span is connected in a communicating relationship to the first line module and a second mode being such that the span is connected in a communicating relationship to the second line module, the input device changing from the first mode to the second mode in response to a changeover signal; and

a data processor configured to respond to a malfunction of the first line module by instructing the second line module to transmit received telecommunications signals to the switching matrix and further configured to generate the changeover signal to functionally replace the first line module with the second line module.

16. A switch according to claim 15 further comprising:

an I/O bus located such that when the active input device is in the second mode, the span is in electrical communication with the I/O bus; and

a standby input device having a plurality of connection modes, a first mode of the standby input device connecting the I/O bus to the second line module and a second mode of the standby input device disconnecting the I/O bus from the second line module, the standby input device changing from the first mode to the second mode in response to a standby signal generated by the data processor in response to said malfunction of the first line module.

17. A switch according to claim 16 further comprising:

a first line card on which a plurality of line modules are located including the first line module; and

a second line card on which a plurality of line modules are located including the second line module.

18. A switch according to claim 17 wherein the first line card comprises a circuit board having an edge connector by which the modules of the first line card make electrical connection with the data processor and the active input device and wherein the second line card comprises a circuit board having an edge connector by which the modules of the second line card make electrical connection with the data processor and the active input device.

19. In a programmable telecommunications switch, having a switching matrix for dynamically connecting and disconnecting communication paths between a plurality of communication channels and a first independently instructable line module arranged to receive a telecommunications signal and transmit the telecommunications signal to a first predetermined communication channel of said plurality of communication channels of the switching matrix, a method of rerouting the telecommunications signal upon a malfunction of the first line module, the method comprising:

providing a second independently instructable line module functionally compatible with the first line module, arranged to receive said telecommunications signal and transmit the telecommunications signal to said plurality of communication channels of the switching matrix in accordance with an instruction signal;

providing an active input device which terminates an external span carrying the telecommunications signal and which has a plurality of connection modes, a first mode being such that the span is connected in a communicating relationship to the first line module and a second mode being such that the span is connected in a communicating relationship to the second line module, the active input device changing from the first mode to the second mode in response to a changeover signal;

providing a data processor which is responsive to a malfunction of the first line module;

generating, by the data processor, an instruction signal to the second line module to cause the second line module to transmit said telecommunications signal over said first communication channel of the switching matrix; and

generating the changeover signal with the data processor in response to a malfunction of the first line module, thereby decoupling the first line module from the switch matrix and functionally replacing the first line module with the second line module, the second line module thereafter transmitting the telecommunications signal to said first communication channel of the switch matrix.

20. A method according to claim 19 further comprising locating the first line module on a printed circuit board which may be physically inserted and removed from the switch.

21. A method according to claim 20 further comprising providing the circuit board with an edge connector by which the first line module makes electrical connection with the data processor and the active input device.

22. A method according to claim 20 further comprising:

providing a main power source from which the switching matrix, the first line module, the second line module, the active input device and the data processor all receive electrical power; and

providing a precharge power source which, upon insertion of the circuit board, provides power to the first line module before the first line module receives power from the main power source.

23. A method according to claim 19 further comprising:

connecting the span to the second line module via an I/O bus and a standby input device when the active input device is in the second mode, the standby input device having a plurality of connection modes, a first mode of the standby input device connecting the I/O bus to the second line module and a second mode of the standby input device disconnecting the I/O bus from the second line module; and

generating a standby signal with the data processor which changes the standby input device from the first mode to the second mode in response to a malfunction of the first line module.

24. A method according to claim 23 further comprising:

locating the first line module on a first line card which has a plurality of line modules; and

locating the second line module on a second line card which has a plurality of line modules.

25. In a programmable telecommunications switch having a switching matrix for dynamically connecting and disconnecting communications paths between a plurality of communication channels, first and second functionally compatible and independently instructable line cards arranged to receive telecommunications signals and transmit the telecommunications signals to a selected one of the plurality of communication channels of the switching matrix, a method of rerouting a telecommunications signal from the first line card to the second line card, wherein the first line card is transmitting the telecommunications signal to a first communication channel, the method comprising:

providing an I/O bus arranged to carry telecommunications signals;

providing an active I/O card which terminates a plurality of external spans carrying telecommunications signals and has a plurality of connection modes, a first mode connecting the spans in a communicating relationship to the first line card, and a second mode connecting the spans in a communicating relationship to the I/O bus;

providing a standby I/O card having a plurality of connection modes, a first connection mode connecting the second line card in a communicating relationship to the I/O bus, and a second mode disconnecting the second line card from the I/O bus;

providing a data processor which is responsive to a malfunction of the first line card;

instructing the second line card to transmit the telecommunication signal to said first communication channel; and

generating with the data processor, upon malfunction of the first line card, a standby signal which is received by the standby I/O card and causes the standby I/O card to change from one mode to another, and a changeover signal which is received by the active I/O card and causes the active I/O card to change from one mode to the other to functionally replace the first line card with the second line card, the telecommunications signal thereafter received by the second line card and transmitted by the second line card to the first communication channel of the switch matrix.

26. In a programmable telecommunications switch having a switching matrix for dynamically connecting or disconnecting communications paths between a plurality of communication channels and a plurality of functionally compatible and independently instructable line cards each arranged to receive a telecommunications signal and transmit the telecommunications signal to a selectable one of the plurality of communication channels of the switching matrix, a method of providing redundancy to the line cards, the method comprising:

providing a plurality of active I/O cards, each of which terminates a plurality of external spans carrying telecommunications signals and each of which has a plurality of connection modes including a first mode in which it connects the spans to a line card associated with that active I/O card;

providing a plurality of I/O busses arranged such that each active I/O card connects the spans it terminates to a different one of said I/O busses for each of its connection modes other than the first mode;

providing a plurality of standby I/O cards each having a plurality of connection modes and being arranged such that different connection modes of a standby I/O card correspond to a line card associated with that standby I/O card being connected to a different one of the I/O busses;

providing a data processor which is responsive to a malfunction of one of the line cards, the malfunctioning line card configured to transmit the telecommunications signal to a first communication channel of the switch matrix;

generating with the data processor, in response to a malfunction of one of the line cards, a distinct changeover signal specific to a particular active I/O card associated with the malfunctioning line card to change the mode of said particular active I/O card, and a distinct standby signal specific to a particular standby I/O card to change the connection mode of said particular standby I/O card, the resulting mode change of the particular I/O card and standby I/O card resulting in the spans terminated on the particular I/O card being connected to a designated I/O bus and the particular standby I/O card connecting the line card with which it is associated to said designated I/O bus; and

instructing the line card associated with the particular standby I/O card to transmit the telecommunications signal to the first communication channel of the switch matrix.