Lantronix
LSS2200-8P Install Guide
40
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
must 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. This isolation
between ports requirement de facto determines a completely separate power supply per port, which makes multi-
port PSEs for outdoor PD deployment impractical. Environment B is therefore an indoor PSE-outdoor PD (a.k.a.
indoor/outdoor) or outdoor PSE-outdoor PD (a.k.a. outdoor/outdoor) environment.
This means that only single-port PSEs should normally be used when PDs are deployed outdoors. 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.
Caution
: The switch is an indoor device. If it is to be used with outdoor devices such as outdoor IP cameras or
outdoor Wi-Fi APs, then you are strongly suggested to install a surge protector or surge suppressor to protect the
switch. The switch is compliant with 802.3at in Environment A when using an isolated power supply. For 802.3at
Environment B applications, i.e., building to building, copper to copper endpoint connections: 1) use an Ethernet
network isolator module (PoE disabled), or 2) use mid-span injector (s), e.g., MIL-L100i, L1000i-at, between this
switch’s PSE port and link partner PD port.
Mode A vs. Mode B
Alternative A, also known as Mode A, uses the data pairs of an Ethernet link to deliver power. Data Pairs include
pins 1,2 and 3,6. PSEs using Mode A supply a positive voltage to pins 1 and 2. Alternative B, also known as
Mode B, uses the spare pairs to deliver power. Spare Pairs include pins 4,5 and 7,8.
802.3af/at Standard “compliant” vs "compatible" PDs
Knowing the difference between PoE "compliant" and "compatible" devices can help avoid interoperability and
connectivity issues. Compliant PoE devices and compatible PoE devices are not held to the same 802.3af/at
standard:
•
802.3af/at “compliant” PDs fulfill the IEEE strict requirement to support both Mode A and Mode B power
modes.
•
802.3af/at "compatible" PDs typically can provide power using only Mode B.
Typical PD Power Requirements
•
1.8 Watts: Lantronix’ M/GE-ISW-SFP-01-PD (Class 1 Powered Device (0.44 - 3.84 Watts).
•
13W: IP Camera, VoIP Phone, Wireless Access Point, Networked Audio.
•
30W: IP Telephone, WiMAX Access Point, PTZ Camera, Remote Computer Terminal.
•
60W : Door Access System, Video Phone, Thin Client.
•
100W: Digital Signage Display, Point-of-Sale System, LCD TV, Computer Monitor.
•
200W: Larger TV, Larger Display, Larger Monitor, Laptop.
After eliminating basic network factors, ask your PD vendor for the PD’s power supply mode and polarities
supported and exact power consumption.