3Com Switch 8800 Configuration Guide
Chapter 51 PoE Configuration
51-1
Chapter 51 PoE Configuration
51.1 PoE Overview
51.1.1 PoE on the Switch
The Switch 8800 supports power-over-Ethernet (PoE). Equipped with external power
supply and PoE-capable cards, Switch 8800s can provide 48 VDC power for remote
powered devices (PDs, such as IP phones, WLAN APs, and Network cameras) through
twisted pairs.
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The Switch 8800 supports IEEE802.3af standard. While they can also supply
power to PDs noncompliant with the standard.
The power supply of the Switch 8800 is administered by the Fabric; each PoE card on
the switch can be viewed as a power sourcing equipment (PSE), which administers the
power supplying of all the ports on it independently.
The Switch 8800 can transmit data and supply power in the mean time through the
signal lines (1, 3, 2, and 6) of the category-3/5 twisted pairs. Using converters, they can
also supply power to the PDs that can be powered only through spare lines (4, 5, 7, and
8).
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The Switch 8800 supplies power through the Ethernet electrical ports on the
service cards. Each service card can supply power to up to 48 remote devices at
the maximum distance of 100 m (328 feet).
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The maximum power that can be supplied by each Ethernet port to its PD is 15.4
W.
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When supplying power to remote devices, the maximum total power that can be
provided by the Switch 8800 is 4500 W (220 V)/2250 W (110V). The switch
determines whether or not to supply power to the next remote PD it discovered
depending on the total power it currently supply.
Note:
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When a remote PD is powered by an Switch 8800, the PD needs not have any
external power supply.
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If the remote PD has an external power supply, the Switch 8800 and the external
power supply will be redundant with each other for the PD.
