Lantronix
SESPM1040-541-LT-xx Install Guide
33772 Rev. F
Page
52
of
64
Requesting and Sourcing Power Type and Class of PoE Device
:
PoE Classes
PoE Classification is where the PSE detects the PD’s power requirements by using Physical Layer Classification or
LLDP. The IEEE 802.3bt standard specifies mutual identification to address four-pair operation. Additional
clauses were added, defining the following:
Class
PSE Output Power[W] PD Input Power[W]
PD Type
Standard
0
15.4
12.95
1
IEEE 802.3af
1
4
3.84
1
2
7
6.49
1
3
15.4
12.95
1
4
30
25.5
2
IEEE 802.3at
5
45
40
3
IEEE 802.3bt
6
60
51
3
7
75
62
4
8
90
73
4
PoE Deployment Environments A and B
IEEE802.3at-2009 defines two deployment environments in section 33.4.1:
Environment A
: when both PSE and PD are located indoors, inside the same building. In this environment, there
has to be electrical isolation between the PoE circuitry and the data circuitry inside a PSE. Multi-port PSE’s can
all share the same ground isolation. Environment A is therefore an
indoor PSE – indoor PD
environment (a.k.a.
indoor/indoor
).
Environment B
: when the PSE and PD are not located in the same building. In this environment there needs to
be electrical isolation between PoE and data, as well as between every port in a multi-port PSE.
In summary, the PD-PSE environment is one of these three combinations:
1. PoE Source is indoor, PD is indoor (Env. A)
2. PoE Source is indoor, PD is outdoor (Env. B)
3. PoE Source is outdoor, PD is outdoor (Env. B)
Option 3 is the most challenging environment since both the PD and PSE are installed outdoors. The switch is an
indoor
or outdoor device. It can be used with outdoor devices such as outdoor IP cameras or outdoor Wi-Fi Aps.