Methods and apparatus for discovering a powerability condition of a computer network

• US 6,701,443 B1
• Filed: 06/19/2000
• Issued: 03/02/2004
• Est. Priority Date: 06/19/2000
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Bell, Robert
• Primary Examiner(s): Lee, Thomas
• Assistant Examiner(s): Patel, Nitin C.
• Application Number:
  US09/596,679
• Time in Patent Office: 1,352 Days
• Field of Search: 713/300, 713/310, 713/340, 700/22-286
• US Class Current: 713/300
• CPC Class Codes: G06F 1/266 Arrangements to supply power to external peripherals either directly from the computer or under computer control, e.g. supply of power through the communication port, computer controlled power-strips
• CPC Class Codes: H04L 12/10 Current supply arrangements

Abstract

The invention is directed to techniques for discovering a powerability condition of a computer network such as the existence of a remotely powerable device attached to a connecting medium of the computer network. Such detection can then control whether a remote power source (e.g., a data communications device such as a switch) provides remote power (e.g., phantom power) to the computer network. One arrangement of the invention is directed to an apparatus for discovering a powerability condition of a computer network. The apparatus includes a signal generator, a detector and a controller which is coupled to the signal generator and the detector. The controller configures the signal generator to provide a test signal to a connecting medium of the computer network, and configures the detector to measure a response signal from the connecting medium of the computer network. The controller then indicates whether a remotely powerable device connects to the connecting medium of the computer network based on the response signal. Accordingly, if the apparatus discovers a remotely powerable device attached to the computer network (i.e., the power requirement condition of the network), the apparatus can provide power to the device remotely (e.g., through the connecting medium). However, if the apparatus does not discover a remotely powerable device attached to the computer network (e.g., another power requirement condition), the apparatus can avoid providing power remotely and thus avoid possibly damaging any non-remotely powerable device on the computer network.

Claims

1. A method for discovering a powerability condition of a computer network, the method comprising the steps of:

providing a test signal to differential signal lines of a connecting medium of the computer network;

measuring a response signal from the differential signal lines of the connecting medium of the computer network; and

indicating whether a remotely powerable device connects to the connecting medium of the computer network based on the response signal;

wherein the step of providing the test signal includes the steps of;

supplying, to the connecting medium, a first voltage during a first time period; and

supplying, to the connecting medium, a second voltage that is substantially different than the first voltage during a second time period;

wherein the step of supplying the first voltage includes the step of;

applying one of a positive and negative test voltage to the connecting medium; and

wherein the step of supplying the second voltage includes the step of;

applying the other of the positive and negative test voltage to the connecting medium.

2. The method of claim 1 wherein the computer network supports connection of a remotely powerable device that receives, during normal operation, an operating voltage having a first voltage magnitude;

and wherein the step of providing the test signal includes the step of;

supplying, as the test signal, a test voltage having a second voltage magnitude that is substantially less than the first voltage magnitude.

3. The method of claim 1 wherein the connecting medium includes a local end and a remote end, and wherein the step of indicating includes the step of:

selectively identifying, through the local end of the connecting medium, one of (i) a backwards wired device condition at the remote end, (ii) an open condition at the remote end, (iii) a remotely powerable device condition at the remote end, and (iv) a shorted/non-powerable device condition at the remote end.

4. The method of claim 1 wherein the differential signal lines of the connecting medium include a first pair of differential signal lines configured to carry data signals between network devices and a second pair of differential signal lines configured to carry other data signals between the network devices, and wherein the step of providing the test signal includes the step of:

applying a DC voltage across the first and second pairs of differential signal lines.

5. The method of claim 4 wherein the step of applying the DC voltage includes the step of:

coupling a signal generator between a centertap of the first pair of differential signal lines and a centertap of the second pair of differential signal lines.

6. The method of claim 4, further comprising the step of:

providing remote power to the computer network through the first and second pairs of differential signal lines to remotely power a device.

7. A method for discovering a powerability condition of a computer network, the method comprising the steps of:

providing a test signal to a connecting medium of the computer network;

measuring a response signal from the connecting medium of the computer network; and

indicating whether a remotely powerable device connects to the connecting medium of the computer network based on the response signal, wherein the connecting medium includes (i) a first connecting link having a local end that terminates at a first transformer and a remote end, and (ii) a second connecting link having a local end that terminates at a second transformer and a remote end; and

wherein the step of providing the test signal includes the step of;

applying the test signal to the connecting medium through a centertap of the first transformer and a centertap of the second transformer.

8. An apparatus for discovering a powerability condition of a computer network, comprising:

a controller;

a signal generator coupled to the controller; and

a detector coupled to the controller, the controller (i) configuring the signal generator to provide a test signal to differential signal lines of a connecting medium of the computer network, (ii) configuring the detector to measure a response signal from the differential signal lines of the connecting medium of the computer network, and (iii) indicating whether a remotely powerable device connects to the connecting medium of the computer network based on the response signal;

wherein the controller, when configuring the signal generator to provide the test signal, configures the signal generator to supply to the connecting medium, (i) a first voltage during a first time period, and (ii) a second voltage that is substantially different than the first voltage during a second time period; and

wherein the controller configures the signal generator to apply one of a positive and negative test voltage to the connecting medium as the first voltage, and the other of the positive and negative test voltage to the connecting medium as the second voltage.

9. The apparatus of claim 8 wherein the computer network supports connection of a remotely powerable device that receives, during normal operation, an operating voltage having a first voltage magnitude;

and wherein the controller configures the signal generator to supply, as the test signal, a test voltage having a second voltage magnitude that is substantially less than the first voltage magnitude.

10. The apparatus of claim 8 wherein the connecting medium includes a local end and a remote end, and wherein the controller selectively identifies, through the local end of the connecting medium, one of (i) a backwards wired device condition at the remote end, (ii) an open condition at the remote end, (iii) a remotely powerable device condition at the remote end, and (iv) a shorted/non-powerable device condition at the remote end.

11. The apparatus of claim 8 wherein the differential signal lines of the connecting medium include a first pair of differential signal lines configured to carry data signals between network devices and a second pair of differential signal lines configured to carry other data signals between the network devices;

and wherein the controller, when configuring the signal generator to provide the test signal, is configured to;

direct the signal generator to apply a DC voltage across the first and second pairs of differential signal lines.

12. The apparatus of claim 11 wherein the controller, when directing the signal generator to apply the DC voltage across the first and second pairs of differential signal lines, is configured to:

couple the signal generator between a centertap of the first pair of differential signal lines and a centertap of the second pair of differential signal lines.

13. The apparatus of claim 11 wherein the controller is further configured to:

direct the signal generator to provide remote power to the computer network through the first and second pairs of differential signal lines to remotely power a device.

14. An apparatus for discovering a powerability condition of a computer network, comprising:

a controller;

a signal generator coupled to the controller; and

a detector coupled to the controller, the controller (i) configuring the signal generator to provide a test signal to a connecting medium of the computer network, (ii) configuring the detector to measure a response signal from the connecting medium of the computer network, and (iii) indicating whether a remotely powerable device connects to the connecting medium of the computer network based on the response signal, wherein the connecting medium includes (i) a first connecting link having a local end that terminates at a first transformer and a remote end, and (ii) a second connecting link having a local end that terminates at a second transformer and a remote end; and

wherein the controller configures the signal generator to apply the test signal to the connecting medium through a centertap of the first transformer and a centertap of the second transformer.

15. A method for discovering a powerability condition of a computer network, the method comprising the steps of:

providing a test signal to differential signal lines of a connecting medium of the computer network;

measuring a response signal from the differential signal lines of the connecting medium of the computer network; and

determining whether a backwards-wired remotely powerable device connects to the connecting medium of the computer network based on the response signal, and when it is determined that a backwards-wired remotely powerable device connects to the connecting medium, applying power to the backwards-wired remotely powerable device.