{"id":4717,"date":"2026-05-13T06:29:25","date_gmt":"2026-05-13T06:29:25","guid":{"rendered":"https:\/\/lp.szlogic.cn\/knowledge-center\/ieee-802-3af-vs-ieee-802-3at-vs-ieee-802-3bt\/"},"modified":"2026-05-25T10:25:15","modified_gmt":"2026-05-25T10:25:15","slug":"ieee-802-3af-vs-ieee-802-3at-vs-ieee-802-3bt","status":"publish","type":"post","link":"https:\/\/lp.szlogic.cn\/ru\/knowledge-center\/ieee-802-3af-vs-ieee-802-3at-vs-ieee-802-3bt","title":{"rendered":"Understanding IEEE 802.3af, 802.3at, and 802.3bt: The Evolution of PoE"},"content":{"rendered":"
\"Understanding<\/figure>\n\n\n\n

\ud83d\udd04 <\/strong>Introduction: The Growing Power of Ethernet<\/h2>\n\n\n\n

Power over Ethernet (PoE<\/strong>) has revolutionized how modern networks deliver both data and electrical power over a single cable.
From powering IP phones to high-performance access points and displays, PoE standards\u2014IEEE 802.3af<\/strong><\/a>, 802.3at<\/strong><\/a>, and 802.3bt<\/strong><\/a>\u2014define how much power can safely and efficiently travel through Ethernet cables.<\/p>\n\n\n\n

As connected devices demand higher wattage, PoE technology has evolved to keep pace \u2014 moving from PoE (15.4W)<\/strong> to PoE+ (30W)<\/strong> and finally PoE++ (up to 100W)<\/strong>.<\/p>\n\n\n\n

\ud83d\udd04 <\/strong>Overview of PoE Standards<\/h2>\n\n\n\n
\n\n<\/colgroup>

Attribute \/ Standard<\/p><\/th>

IEEE 802.3af<\/p><\/th>

IEEE 802.3at<\/p><\/th>

IEEE 802.3bt (Type 3)<\/p><\/th>

IEEE 802.3bt (Type 4)<\/p><\/th><\/tr>

Common Name<\/p><\/td>

PoE<\/p><\/td>

PoE+<\/p><\/td>

PoE++<\/p><\/td>

PoE++<\/p><\/td><\/tr>

IEEE Release Year<\/p><\/td>

2003<\/p><\/td>

2009<\/p><\/td>

2018<\/p><\/td>

2018<\/p><\/td><\/tr>

PSE Output Power<\/p><\/td>

15.4W<\/p><\/td>

30W<\/p><\/td>

60W<\/p><\/td>

100W<\/p><\/td><\/tr>

PD Power Available<\/p><\/td>

12.95W<\/p><\/td>

25.5W<\/p><\/td>

51W<\/p><\/td>

71\u201390W<\/p><\/td><\/tr>

Power Pairs Used<\/p><\/td>

2 pairs<\/p><\/td>

2 pairs<\/p><\/td>

4 pairs<\/p><\/td>

4 pairs<\/p><\/td><\/tr>

Typical Cable Type<\/p><\/td>

Cat5 or higher<\/p><\/td>

Cat5e or higher<\/p><\/td>

Cat5e\/Cat6<\/p><\/td>

Cat6\/Cat6A<\/p><\/td><\/tr>

Key Applications<\/p><\/td>

VoIP phones, IP cameras, wireless APs<\/p><\/td>

PTZ cameras, dual-band APs, thin clients<\/p><\/td>

Wi-Fi 6 APs, LED lighting, building automation<\/p><\/td>

Digital signage, IoT gateways, mini PCs<\/p><\/td><\/tr><\/tbody>\n<\/table>\n<\/figure>\n\n\n\n

\ud83d\udd04 <\/strong>Technical Comparison and Power Delivery<\/h2>\n\n\n\n
\"Technical<\/figure>\n\n\n\n

1. IEEE 802.3af (PoE)<\/a><\/h3>\n\n\n\n