Redundant power and data in a wired data telecommunications network

• US 8,549,331 B2
• Filed: 09/03/2010
• Issued: 10/01/2013
• Est. Priority Date: 10/07/2004
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Karam, Roger A., Cafiero, Luca
• Primary Examiner(s): BUTLER, DENNIS
• Application Number:
  US12/875,489
• Publication Number:
  US 20110004779A1
• Time in Patent Office: 1,124 Days
• Field of Search: None
• US Class Current: 713/300
• CPC Class Codes: H04L 1/22 using redundant apparatus to increase reliability
• CPC Class Codes: H04L 12/10 Current supply arrangements
• CPC Class Codes: H04L 41/06 Management of faults, events, alarms or notifications

Abstract

Redundancy of data and/or inline power in a wired data telecommunications network from a pair of network devices via a selection device is provided by communicating redundant signals with each of the pair of network devices and coupling ports of the first network device and corresponding ports of the second network device to paired inputs of the selection device. The selection device operates: 1) under the control of the pair of network devices, one acting as master and one as slave, the master selecting (for each port or for all ports) one of the two paired inputs and causing the selection device to communicate data and/or inline power via a third port of the selection device to a third network device receiving data connectivity and/or inline power from the selection device; or 2) to route two redundant signals to a third network device which then selects one for use.

Claims

1. A powered device for selectively biasing on diode switches in a Power over Ethernet (PoE) system, comprising:

a first terminal arranged to couple to a power source equipment (PSE) through a first pair of diodes;

a second terminal arranged to couple to the PSE through a second pair of diodes;

a threshold detection circuit for monitoring an inline power voltage between the first terminal and the second terminal;

a switch controlled by the threshold detection circuit; and

a load circuit coupled in series with the switch to receive power applied between the first terminal and the second terminal when the switch is closed;

the threshold detection circuit arranged to close the switch when the inline power voltage is within a first range of voltage levels and to open the switch when the inline power voltage exceeds said first range of voltage levels.

2. The powered device of claim 1, wherein:

the first range of voltage levels is less than about 5 volts DC.

3. The powered device of claim 2, wherein:

the load circuit comprises circuitry for forward-biasing signal diodes.

4. The powered device of claim 2, wherein the load circuit has a resistance of approximately 12,500 ohms.

5. The powered device of claim 4, further comprising a PoE identity network including a 25,000-ohm resistance.

6. The powered device of claim 4, further comprising:

a first pair of terminals arranged to couple to the PSE;

a second pair of terminals arranged to couple to a second PSE;

a first relay coupled across the first pair of terminals and arranged to selectively short circuit the first pair of terminals; and

a second relay coupled across the second pair of terminals and arranged to selectively short circuit the second pair of terminals.

7. The powered device of claim 6, further comprising:

first voltage sense circuitry coupled to the first pair of terminals;

second voltage sense circuitry coupled to the second pair of terminals;

first control circuitry coupled to a relay coil of the first relay; and

second control circuitry coupled to a relay coil of the second relay,

wherein the first control circuitry is operative in response to the second voltage sense circuitry for opening and closing the first relay, and

wherein the second control circuitry is operative in response to the first voltage sense circuitry for opening and closing the second relay.

8. The powered device of claim 7, further comprising first common mode communication circuitry coupled to the first control circuitry and including a switchable current source coupled to the first terminal and the second terminal for creating a modulated current signal detectable by the PSE.

9. The powered device of claim 8, further comprising second common mode communication circuitry coupled to the second control circuitry and including a switchable current source coupled to the first terminal and the second terminal for creating a modulated current signal detectable by the PSE.

10. A power over Ethernet (PoE) system, comprising:

a power source equipment (PSE);

a second device;

a selector coupled to the second device;

a first pair of diodes coupled between the PSE and the selector; and

a second pair of diodes coupled between the PSE and the selector,

wherein the selector includes a powered device for selectively biasing on the first pair of diodes and the second pair of diodes to selective enable data communication between the first PSE and the second device,

the powered device including;

a first terminal arranged to couple to the PSE through the first pair of diodes;

a second terminal arranged to couple to the PSE through the second pair of diodes;

a threshold detection circuit for monitoring an inline power voltage between the first terminal and the second terminal;

a switch controlled by the threshold detection circuit; and

a load circuit coupled in series with the switch to receive power applied between the first terminal and the second terminal when the switch is closed;

the threshold detection circuit arranged to close the switch when the inline power voltage is within a first range of voltage levels and to open the switch when the inline power voltage exceeds said first range of voltage levels.

11. The PoE system of claim 10, wherein the first range of voltage levels is less than a voltage level employed by the PSE to perform a discovery operation of powered devices coupled to the PSE.

12. The PoE system of claim 10, wherein the powered device further includes:

a first pair of terminals arranged to couple to the PSE;

a second pair of terminals arranged to couple to a second PSE;

a first relay coupled across the first pair of terminals and arranged to selectively short circuit the first pair of terminals; and

a second relay coupled across the second pair of terminals and arranged to selectively short circuit the second pair of terminals.

13. The PoE system of claim 12, wherein the powered device further includes:

first voltage sense circuitry coupled to the first pair of terminals;

second voltage sense circuitry coupled to the second pair of terminals;

first control circuitry coupled to a relay coil of the first relay; and

second control circuitry coupled to a relay coil of the second relay,

wherein the first control circuitry is operative in response to the second voltage sense circuitry for opening and closing the first relay, and

wherein the second control circuitry is operative in response to the first voltage sense circuitry for opening and closing the second relay.

14. The PoE system of claim 13, wherein the powered device further includes:

first common mode communication circuitry coupled to the first control circuitry and including a switchable current source coupled to the first terminal and the second terminal for creating a modulated current signal detectable by the first PSE and the second PSE.

15. The PoE system of claim 14, wherein the powered device further includes:

second common mode communication circuitry coupled to the second control circuitry and including a switchable current source coupled to the first terminal and the second terminal for creating a modulated current signal detectable by the first PSE and the second PSE.

16. A method of using a powered device in a power over Ethernet (PoE) system, comprising:

monitoring an inline power voltage between a first terminal and a second terminal, the first terminal coupled to a power source equipment (PSE) through a first pair of diodes and a second terminal coupled to the PSE through a second pair of diodes;

receiving the inline power voltage by a switch coupled in series with a load circuit;

closing the switch to allow current to flow through the load circuit when monitoring indicates that the inline power voltage is within a first range of voltage levels; and

opening the switch to prevent current from flowing through the load circuit when the inline power voltage exceeds said first range of voltage levels.

17. The method of claim 16, wherein closing the switch causes a current to flow across each of the first pair of diodes, and wherein the method further comprises:

transmitting data electronically from the first PSE to a third device through the first pair of diodes.

18. The method of claim 17, wherein opening the switch causes substantially no current to flow across each of the first pair of diodes, and wherein the method further comprises:

blocking data from being transmitted electronically from the first PSE to the third device through the first pair of diodes.

19. The method of claim 18, further comprising modulating a current drawn from the first PSE to communicate with the first PSE.

20. The method of claim 18, further comprising short circuiting an input coupled to the first PSE to direct the first PSE to shut itself down.