Cisco Aironet 1300 Power Injector - LR2T AIR-PWRINJ-BLR2T= Manuel D’Utilisation
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R E V I E W D R A F T — C I S C O C O N F I D E N T I A L
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Cisco Aironet Power over Ethernet Application Note
Types of Power over Ethernet
IEEE 802.3af Power
The IEEE 802.af-2003 PoE standard:
•
Defines terminology to describe a port that acts as a power source to a powered device.
•
Defines how a powered device is detected.
•
Defines two methods of delivering PoE to the discovered device requiring power.
•
End-Point PSE—PoE-capable Ethernet port. Power may be delivered by an end-point PSE to a
powered device using the active data wires of an Ethernet port or the spare wires. An end-point
PSE, such as a PoE-capable Ethernet switch may implement either scheme.
powered device using the active data wires of an Ethernet port or the spare wires. An end-point
PSE, such as a PoE-capable Ethernet switch may implement either scheme.
•
Mid-span PSE—Can be used to deliver PoE if an existing non-PoE-capable Ethernet switch is
used. If a mid-span PSE is used, it can only implement power delivery over the spare pairs of
the copper cabling and cannot be used to deliver PoE over 1000BASE-T connections.
used. If a mid-span PSE is used, it can only implement power delivery over the spare pairs of
the copper cabling and cannot be used to deliver PoE over 1000BASE-T connections.
Note
Only one mechanism may be used at a time to deliver power to a powered device because the design of
the device.
the device.
Figure 1
End-Point PSE PoE Delivery
Power delivery, supported within Cisco Catalyst Ethernet switches, relies on the data pairs (pins 1-2 and
3-6) to transmit power (sometimes referred to as “phantom” power). The second mechanism relies on
the unused data pairs (pins 4-5 and 7-8) to deliver power that is supported within mid-span power
delivery.
3-6) to transmit power (sometimes referred to as “phantom” power). The second mechanism relies on
the unused data pairs (pins 4-5 and 7-8) to deliver power that is supported within mid-span power
delivery.
IEEE 802.3at Power
In September 2005, the IEEE began work on a higher power standard for PoE. This standard has not yet
been ratified. Unlike 802.3af (which has a limit of 15.4 watts and must work with the limitations of
Category 3 cable), IEEE twice the PoE power support (approximately 30 watts using two pairs).
been ratified. Unlike 802.3af (which has a limit of 15.4 watts and must work with the limitations of
Category 3 cable), IEEE twice the PoE power support (approximately 30 watts using two pairs).
Although still in discussion, the standard may include PoE power support as high as 60 watts (using four
pairs). The main purpose of 802.3at is to enable more power to operate over an Ethernet cable.
Additionally, the task force has agreed to allow gigabit mid-span products and has granted them the
ability to choose either active data pairs or spare pairs for the power delivery.
pairs). The main purpose of 802.3at is to enable more power to operate over an Ethernet cable.
Additionally, the task force has agreed to allow gigabit mid-span products and has granted them the
ability to choose either active data pairs or spare pairs for the power delivery.
End-Point PSE Power
over Ethernet Delivery
10/100/1000BaseT
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