Which standard defines Power over Ethernet used to supply power through Ethernet cables?

Which standard defines Power over Ethernet used to supply power through Ethernet cables?

• A. IEEE 802.3af
• B. IEEE 802.11ac
• C. IEEE 802.3bt
• D. IEEE 802.1Q

Answer: (A)

Power over Ethernet lets you deliver electrical power over the same Ethernet cable that carries data, so devices like cameras or IP phones can be powered from the network switch without a separate power supply. The standard that defines this capability is IEEE 802.3af. It specifies up to about 15.4 watts provided by the power sourcing equipment, with roughly 12.95 watts reaching the device after cable losses. Power can be delivered either on spare pairs or by injecting power onto the data pairs (phantom power), depending on the Ethernet mode. This standard established PoE, with later amendments (such as 802.3at and 802.3bt) increasing available power for higher-demand devices. Other options listed relate to wireless networking or VLAN tagging, not PoE.

Power over Ethernet lets you deliver electrical power over the same Ethernet cable that carries data, so devices like cameras or IP phones can be powered from the network switch without a separate power supply. The standard that defines this capability is IEEE 802.3af. It specifies up to about 15.4 watts provided by the power sourcing equipment, with roughly 12.95 watts reaching the device after cable losses. Power can be delivered either on spare pairs or by injecting power onto the data pairs (phantom power), depending on the Ethernet mode. This standard established PoE, with later amendments (such as 802.3at and 802.3bt) increasing available power for higher-demand devices. Other options listed relate to wireless networking or VLAN tagging, not PoE.