System and method for controlling power delivered to a powered device based on channel impediments

• US 8,576,873 B2
• Filed: 11/30/2006
• Issued: 11/05/2013
• Est. Priority Date: 11/30/2006
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Diab, Wael William
• Primary Examiner(s): Moore, Jr., Michael J
• Application Number:
  US11/606,292
• Publication Number:
  US 20080129118A1
• Time in Patent Office: 2,532 Days
• Field of Search: 713/300, 713/324, 713/320, 713/310, 439/620.18, 370/493, 370/352, 370/412, 370/468, 375/240.01
• US Class Current: 370/463
• CPC Class Codes: H04L 12/10 Current supply arrangements

Abstract

A system and method for discovering channel impediments for Power over Ethernet (PoE) applications. Cabling power loss in PoE applications is related to the resistance of the cable itself. A PHY can be designed to measure electrical characteristics (e.g., insertion loss, cross talk, length, discontinuities, etc.) of the Ethernet cable to enable determination of the cable resistance. The determined resistance can be used in powering decisions and in adjusting power budgets allocated to power source equipment ports.

Claims

1. A method in a power over Ethernet system that delivers power from a power source equipment to a powered device, said power over Ethernet system being designed for cable lengths up to a maximum of 100 meters, comprising:

upon connection of said powered device to a power source equipment port via an Ethernet cable link that has a length greater than said maximum length of 100 meters, measuring by a cable detection component in said power source equipment, electrical characteristics of said Ethernet cable link;

determining whether connectors exist in a middle of said Ethernet cable link, said determining being based on an identification of discontinuities in said Ethernet cable link based on said measured electrical characteristics;

validating an installation of said power source equipment port prior to a delivery of power to said powered device over said Ethernet cable link, said validation including estimating a resistance of said Ethernet cable link using said determined existence of said connectors, identifying a new maximum cable length limit greater than 100 meters, and determining whether a length of said Ethernet cable link is less than said new maximum cable length limit to produce a validation result that determines whether to initiate said delivery of power to said powered device over said Ethernet cable link; and

if it is determined that said delivery of power is to be initiated, then allocating a power budget to said power source equipment port, said allocated power budget being determined based on said determined existence of said connectors.

2. The method of claim 1, wherein said allocated power budget is based on a cable type, cable length, and an existence of connectors in the middle of said Ethernet cable link.

3. The method of claim 1, wherein said identifying comprises dividing a worst case estimate of a resistance for a port installation using 100 meters of Category 3 cable divided by said estimated resistance of said Ethernet cable link.

4. The method of claim 1, wherein said determining comprises determining after detecting a presence of said powered device and after classification of said powered device.

5. A power over Ethernet system, comprising:

a powered device detection component that detects a presence of a powered device, said powered device coupled to a power source equipment port via an Ethernet cable link;

a cable detection component that measures an electrical characteristic of said Ethernet cable to identify an existence of connectors on said Ethernet cable link, wherein said cable detection component measures discontinuities in said Ethernet cable link; and

a power controller that validates an installation of said power source equipment port prior to a delivery of power to said powered device over said Ethernet cable link, said validation using said identified existence of said connectors to produce a validation result that determines whether said power controller is to initiate a delivery of power to said powered device over said Ethernet cable link, wherein said validation is for an Ethernet cable link having a length greater than 100 meters and compares characteristics of said Ethernet cable link to a cable validation limit that is derived by dividing a worst case estimate of a resistance for a port installation using 100 meters of Category 3 cable by a resistance of said Ethernet cable link with connectors, wherein if said power controller initiates said delivery of power, said power controller allocates a power budget to said power source equipment port, said power budget being determined based on said identified existence of connectors in said Ethernet cable link.

6. The power over Ethernet system of claim 5, wherein said power controller allocates a power budget to said power source equipment port based on a cable type, cable length, and said existence of connectors.

7. A method in a power over Ethernet system that delivers power from a power source equipment to a powered device, comprising:

upon connection of said powered device to a power source equipment port via an Ethernet cable link that has a length greater than 100 meters, measuring by a cable detection component in said power source equipment, electrical characteristics of said Ethernet cable link;

determining whether connectors exist in a middle of said Ethernet cable link, said determining being based on an identification of discontinuities in said Ethernet cable link based on said measured electrical characteristics;

validating an installation of said power source equipment port, said validation including estimating a resistance of said Ethernet cable link using said determined existence of said connectors, identifying a cable length limit greater than 100 meters, and determining whether a length of said Ethernet cable link is less than said cable length limit; and

allocating a power budget to said power source equipment port based on said determined existence of said connectors.

8. The method of claim 7, wherein said allocated power budget is based on a cable type, cable length, and said determined existence of said connectors.

9. The method of claim 7, wherein said identifying comprises dividing a worst case estimate of a resistance for a port installation using 100 meters of Category 3 cable divided by said estimated resistance of said Ethernet cable link.

10. The method of claim 7, wherein said determining comprises determining after detecting a presence of said powered device and after classification of said powered device.