1
U
SE
R
M
AN
U
AL
N
S6
/N
S1
2P
/N
S1
2P
F
Power over Ethernet
The IEEE 802.3AF Ethernet Protocol allows the XLNT NS-product
range to transport both power and Ethernet data on a single CAT5,
CAT5E or CAT6 compliant Ethernetcable.
An IEEE 802.3AF compliant Power over Ethernet device uses a ne-
gotiation procedure to establish if and how much power should be
allocated. The implementation of this negotiation procedure allows
powered and unpowered devices to be interconnected, without any
risk of damage.
The IEEE 802.3AF Ethernet protocol states that power will be pro-
vided on 2 unused datapairs in Ethernet cables. This protocol also
allows the use of Midspan power injection.
Since these wires are thin, a limit has been set in order to avoid any
risk of overcurrent or loss of electrical power due to wire resistance.
During the negotiation procedure a PoE classification will be sent.
This classification determines how much power will be required and
allocated. The output power per port is higher than the maximum
consumption to allow for energy loss in Ethernet cables.
When all of the available power of an Ethernet Switch (like the NS12P
Ethernet switch) is allocated, a protection mode will be activated,
which will stop the allocation of power to newly connected devices.
Example:
When connecting 11 Class 2 devices to an NS12P Ethernet switch
(maximum allocatable power is 100 Watts) the total amount of al-
located power is 11x 7 Watt = 77 Watt.
When connecting 6 Class 3 devices to an NS12P Ethernet switch the
total of allocated power is 6x 15 Watt = 90 Watt.
Chapter 1
Description
IEEE
802.3AF
Max.
output power
Max.
consumption
Class description
Class 0
15,4 Watt
12,95 Watt Unknown Power
Class 1
4 Watt
3,84 Watt Low Power
Class 2
7 Watt
6,49 Watt Medium Power
class 3
15,4 Watt
12,95 Watt High or Full Power
class 4
15,4 watt
12,95 watt Reserved (power as Class 0)
