3Com AirConnect 9550, User Manual

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Key Product Features 11
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Maintaining support for existing 802.11b and 802.11g users
and the existing wireless investment while providing for
expansion into 802.11n.
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Implementing a complete wireless LAN solution, including
Ethernet Adapters, gateways, access points and clients; Wi-Fi
certification guarantees compatibility among vendors.
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Providing access to hot spots in public spaces such as coffee
shops or university cafeterias.
IEEE 802.3af
The IEEE 802.3af-2003 Power over Ethernet standard defines
terminology to describe a port that acts as a power source (PSE)
to a powered device (PD). The IEEE 802.3af standard states that
power may be delivered by an end-point PSE, using either the
active data wires of an Ethernet port or the spare wires, to a
powered device. An end-point PSE, such as a Power over
Ethernet capable Ethernet switch, may implement either scheme.
If a mid-span PSE is used, then the mid-span PSE can only
implement power delivery over the spare pairs of the copper
cabling and cannot be used to deliver Power over Ethernet over
1000BASE-T connections. It should be noted that even if a device
supports both methods of providing power, only one mechanism
may be used to deliver power to a powered device.
The first mechanism is to use the data pairs (pins 1, 2 & 3, 6) to
transmit power, which is sometimes referred to as "phantom"
power. The second power delivery mechanism is to use the