PoE (Power over Ethernet) Support
PoE (Power over Ethernet) Support
The switch is 802.3af compliant, which means it can provide power over Ethernet cable connections from its 48, RJ45 front panel connectors to PDs in the network.
Power over Ethernet (PoE) refers to the ability to provide 48 Vdc power to a powered device using the same Ethernet cabling that provides data. Modern Ethernet implementations employ differential signals over twisted pair cables. This requires a minimum of two twisted pairs for a single physical link. Both ends of the cable are isolated with transformers blocking any DC or common mode voltage on the signal pair. PoE exploits this fact by using two twisted pairs as the two conductors to supply a direct current. One pair carries the power supply current and the other pair provides a path for the return current. While several proprietary legacy implementations of PoE have been deployed by LAN equipment vendors, in 2003 the IEEE published the IEEE 802.3af‐2003 specification, which is part of the 802.3 suite of standards.
The switch is fully compliant with the IEEE 802.3af standard. It supports the standard resistor‐based detection method, as well as AC disconnect capability. The switch is also capable of supplying 7.5 watts of power to all ports simultaneously. Support is also provided for the 802.3af‐defined maximum of 15.4 watts.
Each PD (Powered Device) has a PDC (Powered Device Classification) that is transmitted to the switch for power management purposes. Table 1‐1 on page 1‐5 lists the classifications and the associated power ranges.
Table 1-1 Powered Device Classifications
Class | Usage | PD Maximum Power Range |
Usage | ||
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None | Default | 0.44 to 12.95 Watts |
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1 | Optional | 0.44 to 3.84 Watts |
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2 | Optional | 3.84 to 6.49 Watts |
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3 | Optional | 6.49 to 12.95 Watts |
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4 | Not Allowed | Reserved for Future Use |
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SecureStack C3 Installation Guide
