User Manual

Chapter 1: Overview

Implementation A standard Ethernet twisted pair cable contains four pairs of strands for a

total of eight strands. 10/100 Mbps network traffic requires only four

strands, leaving four strands in the cable unused. The strands that carry

the network traffic are 1, 2, 3, and 6, and the spare strands are 4, 5, 7, and

The IEEE 802.3af standard, which is the standard for PoE, describes two

modes for delivering power to the powered device over twisted pair

cabling. Mode A uses the same strands that carry the network traffic.

Mode B uses the spare strands. The PoE implementation on the

AT-FS708/POE Fast Ethernet switch is Mode B, where power is

transmitted over strands 4, 5, 7, and 8.

Powered devices that comply with the IEEE 802.3af standard typically

support both power delivery methods. So long as a powered device is

compliant with the standard, it should be able to receive its power from the

switch.

The PoE feature on the AT-FS708/POE Fast Ethernet switch should also

work with most legacy powered devices as long as the device can be

manufactured before the IEEE 802.3af standard was completed and,

consequently, may not adhere to the standard.