Patent Application
20090164805
1. Field of the Invention
The present invention relates generally to Power over Ethernet (PoE) and, more particularly, to a system and method for enabling PoE for legacy devices.
2. Introduction
The IEEE 802.3af and 802.3at PoE specifications provide a framework for delivery of power from power sourcing equipment (PSE) to a powered device (PD) over Ethernet cabling. Various types of PDs exist, including voice over IP (VoIP) phones, wireless LAN access points, Bluetooth access points, network cameras, computing devices, etc.
In the PoE process, a valid device detection is first performed. This detection process identifies whether or not it is connected to a valid device to ensure that power is not applied to non-PoE capable devices.
After a valid PD is discovered, the PSE can optionally perform a power classification. In a conventional 802.3af allocation, each PD would initially be assigned a 15.4 W power classification after a Layer 1 discovery process. An optional classification process could then reclassify the PD to a lower power level. In more complex PoE schemes, a Layer 2 classification engine can be used to reclassify the PD. Layer 2 classification processes can be included in PoE systems such as 802.3af, 802.3at or proprietary schemes. In general, Layer 2 communication (e.g., LLDP) can be used to enable a determination of an amount of power to be allocated to a PD. Where a PD such as a computing device has rapidly changing power needs, the Layer 2 communication can be used to transmit various power management information relevant to the PD's current or anticipated needs. Examples of such power management information include battery information, computing device component information, external device information, user information, application information, or the like.
Legacy computing devices (e.g., laptop computers) that have limited or no PoE functionality typically represent a large percentage of the installed base of devices. In rolling out PoE functionality into a corporate environment, the upgrading of the large installed base of legacy devices represents a prohibitive expense. What is needed therefore is a mechanism that enables PoE functionality for such legacy devices.
A system and/or method for enabling PoE for legacy devices, substantially as shown in and/or described in connection with at least one of the figures, as set forth more completely in the claims.
In order to describe the manner in which the above-recited and other advantages and features of the invention can be obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
Various embodiments of the invention are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the invention.
The deployment of power over Ethernet (PoE) systems in an enterprise environment is expected to produce significant benefits. By eliminating the reliance on AC power cords, devices can be flexibly deployed throughout the enterprise environment using a single Ethernet cable for connectivity. This flexibility in deployment also produces significant cost savings as excess electrical wiring, conduits, and outlets need not be installed.
As noted, one example of a device that can benefit from the installation of a PoE system is a computing device. In general, computing devices that are connected to enterprise networks are often connected on a non-permanent basis. For example, a corporate conference room can be designed with network cabling and corresponding power outlets to support the computing devices of 5-20 conference participants. With a PoE system installed, many of the power outlets can be eliminated as power can be alternatively supplied through the existing Ethernet connection.
In realizing the benefits of a PoE system, a computing device would require the inclusion of certain PoE functionality.
As is further illustrated in
In the example of the IEEE 802.3af standard, PSE 120 can deliver up to 15.4 W of power to a plurality of PDs (only one PD is shown in
As would be appreciated, the incorporation of PoE elements 132, 133, 134 into an installed base of computing devices would be prohibitive. This is especially true when considering that the PoE functionality does not represent a core function of the computing device, but rather a measure of convenience for users. The principles of the present invention seek to address the need to accelerate the rollout of PoE functionality in a manner that does not require an overhaul of an installed base of devices.
In general, accessory 210 is designed to provide an interface between a PSE and device 220, which needs upgraded PoE functionality. In the illustrated embodiment, accessory 210 includes transformers 211 designed to receive the wire pairs in an Ethernet cable. The TX and RX wire pairs are passed on to Ethernet port 212, while the center taps of transformers 211 are coupled to PD 216. As noted above, PD 216 can include a PoE module, which contains a signature detection component that enables detection by the PSE, a power controller that controls delivery of power received from the PSE, and circuitry that enables the relay of power demand information to the PSE (e.g., via Layer 2 communication). As illustrated, the resulting power that is extracted by PD 216 from the Ethernet link is forwarded to a power port on device 220. In one embodiment, the power port can represent a standard DC power input port on device 220.
In one embodiment, accessory 210 can be designed to simply produce a DC power output from an Ethernet input. No other communication port need be used. In one scenario, this embodiment can be used in those contexts where device 220 has no PoE functionality. For example, accessory 210 can be designed with basic 802.3af Layer 1 functionality that is designed to get as much power as possible from the PSE to deliver to device 220. In this example, accessory 210 need contain only transformers 211 and PD 216. In another example, accessory 210 can be designed with more advanced Layer 2 functionality to negotiate a power request on behalf of device 220. In this example, accessory 210 could be used to augment non-existent PoE functionality or primitive Layer 1 PoE functionality in device 220. To facilitate this type of functionality, accessory 210 would also include Ethernet port 212 and a processor (not shown) to perform the power request negotiation. In yet another example, accessory 210 can be applied to a legacy device that may already have basic two-pair PoE functionality (e.g., 802.3af). In this example, accessory 210 can be used to provide additional power via alternative pairs (e.g., 802.3at), wherein the additional amount of power can be modulated via Layer 2 communication.
In another embodiment, accessory 210 can be designed to support a communication connection with device 220 in addition to the power connection discussed above. To support the communication connection, accessory 210 also includes switch 213. In the illustrated embodiment, switch 213 is at least a three-port switch that can support Ethernet port 212, communication port 214, and internal port 215. Ports 212, 214, and 215 can support full duplex links such that traffic can be coming from either direction at the same time. Traffic can also be switched to two ports simultaneously. For example, internal port can add traffic to either or both of ports 212, 214, or receive traffic from either or both of ports 212, 214. In one example, traffic to/from Ethernet port 212 and internal port 215 can support PoE power request/priority negotiation between accessory 210 and the PSE, while traffic to/from internal port 215 and communication port 214 can support the exchange of power management information between accessory 210 and device 220.
As noted, the principles of the present invention can also be applied to legacy PDs that lack Layer 2 communication. In the embodiment of
In one embodiment, communication port 214 is an Ethernet port. In this embodiment, Ethernet traffic from the switch can be passed without modification from port 212 to port 214, and on to device 220. In other embodiments, communication port 214 can be embodied as a Bluetooth port, serial port, parallel port, USB port, or any other device-to-device communication mechanism.
As noted, communication port 214 can be used to support the exchange of power management information between accessory 210 and device 220. In one example, device 220 can be configured to provide accessory 210 with information that enables accessory 210 to determine the power needs of device 220. For example, device 220 can be configured to transmit parameters such as battery capacity, battery life, etc. that enables accessory 210 to make a priority decision based on a priority and allocation algorithm.
In another example, device 220 can be configured to perform a priority and allocation algorithm using parameters known to device 220.
To further illustrate the features of the present invention, reference is now made to the flowchart of
The positioning of the accessory between the PSE and the device enables the accessory to act as a PD on behalf of the device. In other words, the accessory can be detected as a PD using the signature detection component incorporated within the accessory. Upon detection of the accessory as a PD, the accessory can then negotiate a power request on behalf of the device at step 406. In one embodiment, the accessory can negotiate the power request independently of the device. In this embodiment, the accessory can request the maximum allowed power that is available from the PSE. Whatever amount of power that is approved can then be transferred to the device using the DC power connection. In another embodiment, the accessory can negotiate the power request using input from the device. In one example, the device can forward power management parameters to the accessory for determination of a power request/priority. In another example, the device can determine the power request/priority using various power management information available to the device, and forward the determined power request/priority to the accessory. Regardless of the type or amount of input that is provided by the device to the accessory, the accessory represents a low-cost mechanism of leveraging new or upgraded PoE capabilities of the PSE without requiring commensurate upgrades at the device.
At step 408, after the accessory has negotiated the power request on behalf of the device, the accessory can then extract power that is delivered to the accessory via the Ethernet cable. The power is extracted using the power controller and power FET in the accessory and delivered to the device at step 410 using the DC power connection.
As has been described, the accessory of the present invention can provide the benefits of the latest PoE technologies to any type of device that needs power. These benefits can be realized without requiring a hardware upgrade of the device. Specifically, any device that has an external DC power port can potentially benefit from the principles of the present invention.
These and other aspects of the present invention will become apparent to those skilled in the art by a review of the preceding detailed description. Although a number of salient features of the present invention have been described above, the invention is capable of other embodiments and of being practiced and carried out in various ways that would be apparent to one of ordinary skill in the art after reading the disclosed invention, therefore the above description should not be considered to be exclusive of these other embodiments. Also, it is to be understood that the phraseology and terminology employed herein are for the purposes of description and should not be regarded as limiting.
