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- .. SPDX-License-Identifier: GPL-2.0
- Power Sourcing Equipment (PSE) in IEEE 802.3 Standard
- =====================================================
- Overview
- --------
- Power Sourcing Equipment (PSE) is essential in networks for delivering power
- along with data over Ethernet cables. It usually refers to devices like
- switches and hubs that supply power to Powered Devices (PDs) such as IP
- cameras, VoIP phones, and wireless access points.
- PSE vs. PoDL PSE
- ----------------
- PSE in the IEEE 802.3 standard generally refers to equipment that provides
- power alongside data over Ethernet cables, typically associated with Power over
- Ethernet (PoE).
- PoDL PSE, or Power over Data Lines PSE, specifically denotes PSEs operating
- with single balanced twisted-pair PHYs, as per Clause 104 of IEEE 802.3. PoDL
- is significant in contexts like automotive and industrial controls where power
- and data delivery over a single pair is advantageous.
- IEEE 802.3-2018 Addendums and Related Clauses
- ---------------------------------------------
- Key addenda to the IEEE 802.3-2018 standard relevant to power delivery over
- Ethernet are as follows:
- - **802.3af (Approved in 2003-06-12)**: Known as PoE in the market, detailed in
- Clause 33, delivering up to 15.4W of power.
- - **802.3at (Approved in 2009-09-11)**: Marketed as PoE+, enhancing PoE as
- covered in Clause 33, increasing power delivery to up to 30W.
- - **802.3bt (Approved in 2018-09-27)**: Known as 4PPoE in the market, outlined
- in Clause 33. Type 3 delivers up to 60W, and Type 4 up to 100W.
- - **802.3bu (Approved in 2016-12-07)**: Formerly referred to as PoDL, detailed
- in Clause 104. Introduces Classes 0 - 9. Class 9 PoDL PSE delivers up to ~65W
- Kernel Naming Convention Recommendations
- ----------------------------------------
- For clarity and consistency within the Linux kernel's networking subsystem, the
- following naming conventions are recommended:
- - For general PSE (PoE) code, use "c33_pse" key words. For example:
- ``enum ethtool_c33_pse_admin_state c33_admin_control;``.
- This aligns with Clause 33, encompassing various PoE forms.
- - For PoDL PSE - specific code, use "podl_pse". For example:
- ``enum ethtool_podl_pse_admin_state podl_admin_control;`` to differentiate
- PoDL PSE settings according to Clause 104.
- Summary of Clause 33: Data Terminal Equipment (DTE) Power via Media Dependent Interface (MDI)
- ---------------------------------------------------------------------------------------------
- Clause 33 of the IEEE 802.3 standard defines the functional and electrical
- characteristics of Powered Device (PD) and Power Sourcing Equipment (PSE).
- These entities enable power delivery using the same generic cabling as for data
- transmission, integrating power with data communication for devices such as
- 10BASE-T, 100BASE-TX, or 1000BASE-T.
- Summary of Clause 104: Power over Data Lines (PoDL) of Single Balanced Twisted-Pair Ethernet
- --------------------------------------------------------------------------------------------
- Clause 104 of the IEEE 802.3 standard delineates the functional and electrical
- characteristics of PoDL Powered Devices (PDs) and PoDL Power Sourcing Equipment
- (PSEs). These are designed for use with single balanced twisted-pair Ethernet
- Physical Layers. In this clause, 'PSE' refers specifically to PoDL PSE, and
- 'PD' to PoDL PD. The key intent is to provide devices with a unified interface
- for both data and the power required to process this data over a single
- balanced twisted-pair Ethernet connection.
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