IEEE 802.3 표준의 Power Sourcing Equipment(PSE)

PSE와 Powered Device

Power Sourcing Equipment(PSE)는 Ethernet cable로 data와 함께 power를 공급하는 network 핵심 장비입니다. 보통 switch나 hub가 PSE 역할을 하고 IP camera, VoIP phone, wireless access point 같은 Powered Device(PD)에 전력을 제공합니다.

.. 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.

일반 PSE와 PoDL PSE

IEEE 802.3에서 일반 PSE는 보통 Power over Ethernet(PoE)과 연관된, Ethernet cable을 통해 data와 함께 power를 공급하는 장비를 뜻합니다.

PoDL PSE(Power over Data Lines PSE)는 IEEE 802.3 Clause 104에 따라 single balanced twisted-pair PHY에서 동작하는 PSE를 구체적으로 가리킵니다. 한 pair로 data와 power를 함께 전달하는 장점 때문에 자동차와 산업 제어 환경에서 중요합니다.

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.

PoE addendum과 kernel 명명 규칙

IEEE 802.3-2018과 관련 addendum은 Ethernet 전력 공급 세대를 정의합니다. `802.3af`는 2003년 승인된 시장명 PoE로 Clause 33에서 최대 15.4W를 제공합니다. `802.3at`는 2009년 승인된 PoE+로 최대 30W입니다.

`802.3bt`는 2018년 승인된 4PPoE이며 Clause 33에서 Type 3은 최대 60W, Type 4는 최대 100W를 제공합니다. `802.3bu`는 2016년 승인되었고 예전 명칭 PoDL로 Clause 104의 Class 0~9를 도입합니다. Class 9 PoDL PSE는 약 65W까지 제공합니다.

Linux networking subsystem에서는 일반 PSE·PoE code에 Clause 33을 나타내는 `c33_pse` keyword를 권장합니다. 예는 `enum ethtool_c33_pse_admin_state c33_admin_control;`입니다.

PoDL-specific code에는 `podl_pse`를 사용합니다. 예를 들어 `enum ethtool_podl_pse_admin_state podl_admin_control;`로 Clause 104의 PoDL 설정을 일반 PoE와 구분합니다.

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.

Clause 33과 Clause 104 요약

IEEE 802.3 Clause 33은 Powered Device와 PSE의 기능·전기적 특성을 정의합니다. 10BASE-T, 100BASE-TX, 1000BASE-T처럼 data 전송에 쓰는 동일한 generic cabling으로 power도 공급하여 전력과 data communication을 통합합니다.

Clause 104는 single balanced twisted-pair Ethernet physical layer용 PoDL PD와 PoDL PSE의 기능·전기적 특성을 정의합니다. 이 clause 안의 `PSE`와 `PD`는 각각 PoDL PSE와 PoDL PD를 뜻합니다. 단일 balanced pair interface로 data와 그 data 처리에 필요한 power를 함께 제공하는 것이 목적입니다.

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.