Symbol Technologies ES3000 Manuel D’Utilisation

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ES3000 User Guide
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4.2.19 System Admin->Ports->Power over Ethernet 
Use Power-over-Ethernet (PoE) to eliminate using a 110/220 VAC power source to power access 
points and other devices on a wired LAN. If using a Power-over-Ethernet system, only a single CAT5 
Ethernet cable carrying both power and data to each device is required. The single cable scheme 
provides greater flexibility in the placement of access points and network devices and can 
significantly decrease installation costs.
Two configuration pages exist for the PoE function. The first allows per port configuration for specific 
power restrictions on an individual port basis. The second configuration page is used for global 
configurations that apply switch-wide.
The ES3000 has a maximum PoE power budget of 170 watts. This is enough to supply 7 watts to all 
24 PoE ports on the switch. The switch supplies a maximum of 16.5 watts per port.When a new 
powered device is connected to a port, the ES3000 switch checks whether enough power remains in 
the power budget to support the device. This decision is based on the actual power drawn by the 
powered devices at the time of connection, rather than their maximum power consumption. If there 
is insufficient power to supply all PoE-enabled ports, the switch does not power all ports. The 
administrator can select the method the ES3000 switch uses to decide which ports receive power. 
The ES3000 can sense whether a powered device is attached to a port. The switch supplies power 
only to devices that need it. The switch initially uses resistance detection (802.3af) to determine 
whether a port requires power. If that fails, and if capacitance detection is enabled, the switch then 
uses capacitance detection to determine whether the port needs power. This allows the switch to 
detect the presence of older powered devices, which might not be 802.3af compliant.