System and method for controlling power delivered to a powered device based on cable characteristics
A system and method for discovering a cable type and resistance 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, 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.
1. A network powering method, comprising:
identifying a type of network cable that connects a powered device to a power source equipment;
determining whether said identified type of network cable indicates that said network cable is qualified for a transmission of power over said network cable, said qualification being determined relative to a cabling specification for said transmission of power over said network cable; and
if it is determined that said identified type of network cable is not qualified for said transmission of power, then validating said non-qualified type of network cable based on an analysis of characteristics of a port installation that includes said network cable and said powered device, said validation representing a condition to an initial provisioning of power to said powered device by said power source equipment.
2. The method of claim 1 , wherein said cabling specification is the IEEE 802.3at specification, and said identifying comprises identifying a Category 3 Ethernet cable.
3. The method of claim 1 , wherein said characteristics of said port installation include a voltage of said powered device and/or said power source equipment.
4. The method of claim 1 , wherein said characteristics of said port installation include a power consumed by said powered device.
5. The method of claim 1 , wherein said characteristics of said port installation include a resistance of said network cable.
6. The method of claim 1 , wherein said characteristics of said port installation include a length of said network cable.
7. A power overEthernet method, comprising:
identifying a length of Ethernet cable that connects a powered device to power source equipment;
determining whether said identified length of Ethernet cable is greater than 100meters; and
if it is determined that said identified length of Ethernet cable is greater than 100 meters, then validating said Ethernet cable for a transmission of power from said power source equipment to said powered device, said validation being based on an analysis of characteristics of a port installation that includes said Ethernet cable and said powered device, said validation representing a condition to an initial provisioning of power by said power source equipment to said powered device over said Ethernet cable.
8. The method of claim 7 , wherein said provisioning of power by said power source equipment to said powered device over said Ethernet cable is in accordance with the IEEE 802.3af specification.
9. The method of claim 7 , wherein said provisioning of power by said power source equipment to said powered device over said Ethernet cable is in accordance with the IEEE 802.3at specification.
10. The method of claim 7 , wherein said characteristics of said port installation include a voltage of said powered device and/or said power source equipment.
11. The method of claim 7 , wherein said characteristics of said port installation include a power consumed by said powered device.
12. The method of claim 7 , wherein said characteristics of said port installation include a resistance of said Ethernet cable.
13. The method of claim 7 , wherein said characteristics of said port installation include a type of said Ethernet cable.
14. The method of claim 7 , wherein said characteristics of said port installation include a length of said Ethernet cable.
15. The method of claim 7 , wherein said identifying comprises identifying a category and a length of said Ethernet cable.
16. A network powering system that delivers power to a powered device via a network cable, comprising:
a transceiver that measures one or more electrical characteristics of said network cable; and
a controller that identifies performance characteristics of said network cable based on said one or more electrical characteristics, said identified performance characteristics being indicative of a type of said network cable, said controller determining whether said identified performance characteristics indicate that said network cable is qualified for a transmission of power over said network cable, said qualification being determined relative to a cabling specification for said transmission of power over said network cable, wherein if it is determined that said identified performance characteristics indicate that said network cable is not qualified for said transmission of power, then said controller validating said non-qualified type of network cable based on an analysis of characteristics of a port installation that includes said network cable and said powered device, said validation representing a condition to an initial provisioning of power to said powered device.
17. The system of claim 16 , wherein said characteristics of said port installation include a voltage of said powered device and/or said power source equipment.
18. The system of claim 16 , wherein said characteristics of said port installation include a power consumed by said powered device.
19. The system of claim 16 , wherein said characteristics of said port installation include a resistance of said network cable.
20. The system of claim 16 , wherein said characteristics of said port installation include a length of said network cable.