What role do pins 4 and 5 play in standard Ethernet connections?

Pins 4 and 5 in standard Ethernet connections (particularly in the 10BASE-T and 100BASE-TX standards) are utilized in specific configurations but do not play a role in basic data transmission. These pins are commonly employed in conjunction with Power over Ethernet (PoE) applications, where they can deliver power to devices like IP cameras and wireless access points. However, in the context of 10/100 Mbps Ethernet connections, when standard data transmission occurs over a twisted-pair cabling, data is typically transmitted over pins 1, 2, 3, and 6 instead.

Therefore, while these pins may be used for PoE, they are not used for standard data communication in the basic Ethernet configurations, which mainly rely on the aforementioned pins. This nuanced understanding is vital for grasping the overall functionality of Ethernet connections, particularly in deployments influenced by PoE technology.