Power Delivery With Alternatives A And B - Allied Telesis AT-IE300-12GP Installation Manual

Chapter 1: Overview
Power Delivery
with Alternatives
A and B
28
Table 4. PoE and PoE+ Powered Device Classes (Continued)
Class
1
2
3
4
The PoE standards define two methods for delivering power over twisted
pair cables from power sources such as the Ethernet switch to powered
devices. The methods, called Alternatives A and B, identify the wire
strands that carry the electrical power over the Ethernet cables to the
powered devices from the power source, which in this case is the IE300
Series switch.
Twisted pair cabling usually has eight strands. For 10Base-T and
100Base-TX devices, the wire strands connected to pins 1, 2, 3, and 6
carry the network traffic while the strands connected to pins 4, 5, 7, and 8
are unused. 1000Base-T devices use all eight strands to carry network
traffic.
For PoE and PoE+ devices, power is delivered over four of the eight
strands. In Alternative A, power is delivered on strands 1, 2, 3, and 6,
which are the same strands that carry the 10/100Base-TX network traffic.
In Alternative B, power is delivered on strands 4, 5, 7, and 8. These are
the unused strands.
For Hi-PoE devices, power is delivered on all eight strands in Ethernet
cabling.
The AT-IE300-12GP Switch supports PoE and PoE+ powered devices
that comply with the IEEE 802.3af and 802.3at standards. The standards
require that powered devices support both Alternatives A and B. However,
legacy PDs that are non-standard or were manufactured before the
completion of the standards might support only one method.
The AT-IE300-12GP Switch supports Alternatives A and B on the twisted
pair ports as follows:
Port 5 to 8 - Alternative A only

Ports 9 to 12 - Alternative A, Alternative B, or both

Maximum
Power Output
Usage
at the Switch
Port
Optional 4.0W
Optional 7.0W
Optional 15.4W
Optional 30.0W
PD Power
Range
0.44W to 3.84W
3.84W to 6.49W
6.49W to
12.95W
12.95W to
25.9W