8-1
8
Power Over Ethernet
Power Over Ethernet (PoE) functionality is supported on certain HP 1820 switch models, enabling designated
switch ports to provide power to connected devices. The devices receiving power through PoE are referred to
as powered devices (PDs).
The switch automatically detects the presence of a PD on a PoE-enabled port, and the switch can learn power
requirements from LLDP messages from the PD. Power allocation can also be configured statically per port.
The PoE software supports sharing the available power among the PoE-enabled ports. Ports are assigned one
of three configurable PoE priority values (High, Low, and None). When more power is requested than is available
on the switch, the switch provides power to a high priority ports before lower priority ports.
Power allocation can be scheduled so that power is supplied only during periods when the PD is actually in use.
PoE Capabilities
The HP 1820 PoE-enabled switches support the original PoE specification (IEEE 802.3af) and the PoE Plus
specification (IEEE 802.1at). IEEE 802.3af, enables providing up to 15.4W of power over a PoE port, whereas
PoE Plus enables providing up to 30W of power.
Table 8-1 shows which ports on each switch support PoE and PoE Plus, along with the maximum power the
switch can provide to all PoE ports combined.
Table 8-1. PoE Ports and Power Capabilities
The maximum power that the switch can provide is configurable on a per-port basis.
Switch Ports that Support PoE Ports that Support PoE
Plus
Maximum Power
Available to All Ports
8-Port PoE Plus Ports 1–4 Any two of Ports 1–4 65W
24-Port PoE Plus Ports 1–12 Any 6 of Ports 1–12 185W
48-Port PoE Plus Ports 1–24 Any 12 of Ports 1–24 370W
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