Method and apparatus for remote powering of device connected to network

• US 7,821,379 B2
• Filed: 05/30/2007
• Issued: 10/26/2010
• Est. Priority Date: 09/27/1999
• Status: Expired due to Fees

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Hang, Soei-Shin, Edsall, Thomas, Cafiero, Luca, De Nicolo, Maurilio, Nakamura, Karl
• Primary Examiner(s): Holloway, III; Edwin C
• Application Number:
  US11/755,542
• Publication Number:
  US 20070222562A1
• Time in Patent Office: 1,245 Days
• Field of Search: 340/310.11, 340/310.13, 340/310.14, 340/310.15, 340/310.16, 340/310.17, 340/310.18, 340/3.51, 340/10.34, 340/10.42, 340/3.9, 379/22.01, 379/93.36, 379/413, 710/62, 713/300, 713/310
• US Class Current: 370/395.2
• CPC Class Codes: H04L 12/10 Current supply arrangements
• CPC Class Codes: H04M 19/08 with current supply sources at the substations generating ringing current H04M19/04

Abstract

A network node determines the suitability of coupled devices for being remotely line powered before actually powering them. The node scan its ports to determine which ports are coupled to devices. The node then interrogates the coupled devices. A unique discovery tone or bit pattern is generated and sent to devices coupled to ports. The node then monitors the port for a return signal. If there is a return signal, it is compared to the transmitted discovery signal. The signal will be identical after allowing for line losses if the coupled device is suitable for remote line powering. If the comparison yields a match, the network node supplies remote line power to the device.

Claims

1. A method for remote line powering, comprising:

operating in a discovery mode for receiving a discovery signal;

looping the discovery signal back when configured for remote line powering;

automatically switching to a remote power mode for receiving remote power after looping back the discovery signal; and

receiving remote power when operating in the remote power mode.

2. The method according to claim 1 including receiving the discovery signal and looping the discovery signal back over an Ethernet cable.

3. The method of claim 1 including receiving at least one initialization packet after receiving remote power.

4. The method of claim 3 including sending an identification packet responsive to the received initialization packet and receiving power from a network node responsive to data in the initialization packet.

5. The method of claim 1 including receiving the remote power overlaid with data signaling.

6. The method of claim 5 directing the remote power to a power line interface and directing the data signaling to a data interface.

7. The method of claim 6 including using the remote power to power a Voice Over Internet Protocol (VoIP) phone and using the data signaling to carry voice calls for the VoIP phone.

8. A system for remote line powering, comprising:

means for receiving a remote power discovery signal at a terminal of a network interface;

means for looping the remote power discovery signal back over the network interface to indicate a remote power capability;

means for receiving remote power after looping the remote power discovery signal back over the network interface; and

means for automatically connecting remote power from the terminal of the network interface to a device interface when remote power is received on the terminal of the network interface.

9. The system according to claim 8 including means for receiving the remote power prior to providing identifying information to a source of the remote power discovery signal.

10. The system according to claim 9 including means for receiving an initialization packet after receiving remote power at the network interface.

11. The system according to claim 10 including means for sending an identification packet responsive to the received initialization packet and receiving the remote power responsive to the identification packet.

12. The system according to claim 8 including means for receiving the remote power overlaid with data signaling on the network interface.

13. The system according to claim 12 including means for directing the remote power to a power line interface and directing the remote data signaling to a device data interface.

14. A network node, comprising:

a processor configured to send a discovery signal over a network interface to determine if network devices are configured to receive remote power, the discovery signal causing the network devices that are configured to receive remote power to automatically switch from an interrogation state to a power receiving state; and

the processor further configured to supply power over the network interface to the network devices that send back a reply signal that matches the discovery signal;

wherein the network node comprises a network switch, router, gateway or controller connected to an Internet Protocol (IP) network and at least one of the network devices comprises an IP endpoint.

15. The network node according to claim 14 wherein the processor outputs the discovery signal over multiple different ports and monitors each of the multiple ports for the reply signal.

16. The network node according to claim 14 wherein the discovery signal is sent over a packet switched network.

17. A method for determining with a network node the suitability of providing remote power to a network device, comprising:

generating a discovery signal;

transmitting the discovery signal from the network node causing the network device to relay the discovery signal back to the network node when the network device is configured for remote powering;

determining that the network device is suitable for powering when the discovery signal is relayed back from the network device; and

determining the device is unsuitable for remote powering when the discovery signal is not relayed back from the network device or when a return signal is received back that does not match the discovery signal.

18. The method according to claim 17 including using a first transmit output for outputting data and a power signal to the network device, and using a second receive input as a power return path when the network device is determined to be suitable for remote powering.

19. The method of claim 17 wherein the network node comprises an Internet switch, router, gateway or controller and the network device comprises an Internet telephone.

20. The method according to claim 17 wherein sending the discovery signal automatically causes the network device to switch from a first state for receiving the discovery signal to a second state for receiving power and data when the network device is configured for remote powering.