Embed Size (px)
Citation preview
Rx +Rx +
Rx -Rx -
Tx +Tx +
Tx -Tx -
DC +
DC +
DC +
DC +
DC -
DC -
DC -
DC -
10/100DC on Spares
10/100Mixed DC & Data
unused
unused
unused
unused
1
2
3
4
5
6
7
8
PINS onSwitch
Mode A Mode B
Class 0: .44 to 12.95
Class 1: .44 to 3.84
Class 2: 3.84 to 6.49
Class 3: 6.49 to 12.95
Watts needed for each class:
Endspan vs Midspan Compatible vs Compliant
PSE
PD
MidspanPoE InjectorSwitch
Key
Data + Power
Data
Endspan Switch IP Camera
IP Camera
En
dsp
anM
idsp
an
1 2 3 4 5 6 7 8
T568A Color
1 2 3 4 5 6 7 8
T568B Color
*Different Types of ClassMode A vs Mode B
PoweredDevice
Power SourcingEquipment
Powered Devices (PD) refer to the group of networking units such as IP cameras, VoIP phones, or WAPs that rely on Power Sourcing
Equipment to operate.
Power Sourcing Equipment (PSE) such as switches, hubs, and injectors, provides power to
Powered Devices.
PSE’s that relay power through their spare pairs (Mode B) are also known as midspan devices while those that relay power through their data pairs (Mode A) are referred to as endspan. End-span devices tend to describe switches with PoE capabilities. Midspan units describe stand alone units (such as injectors) that will usually accompany switches with non-PoE capabilities.
PDs can be categorized
into “classes” depending on their
power requirements. This prevents a PD from
drawing more power than it needs.
*Measured power on PSE’s is usually slightly higher than PDs. Voltage loss is attributed to power dissipation. A PD categorized as Class 0 will receive 12.95 watts of power but the PSE will actually provide 15.4 watts of power.
Powered Devices (PD)
Power Sourcing Equipment (PSE)
1 2 3
1 2 3
A B A+B
A B A+B
Compatible Compatible IEEECompliant
IEEECompliant
IEEECompliant
IEEECompliant
Mode:
Mode:
Compliant PDs support both Mode A or Mode B. Compliant PSE’s can support Mode A, Mode B, or both. Compatible PDs
on the other hand, most likely support only Mode B, but supported modes
vary upon manufacturer.
The Fine Print of PoE Compatibility
