Do you hear about PoE switch?
We know that some of small network devices can be powered by ethernet, that is, we say PoE. PoE switches are the equipment which can power small network device. Now there are not only PoE and PoE+, but also UPoE.
What are their differences?
Power over Ethernet or PoE describes any of several standardized or ad-hoc systems which pass electric power along with data on twisted pair Ethernet cabling. This allows a single cable to provide both data connection and electric power to devices such as wireless access points, IP cameras, and VoIP phones. Its maximum power delivered by PSE is 15.4W.
What’s new in PoE+? That is, the maximum power delivered by PSE of PoE+ is 30W.
How about UPoE?
In 2014, Cisco created another non-standard PoE implementation called Universal Power over Ethernet (UPOE). We also call it PoE++. Its maximum power is 60W.
Cisco Universal Power Over Ethernet (UPOE) extends the IEEE Power over Ethernet Plus (PoE+) standard to double the power per port to 60 watts. It can extend resilient network power to a broad range of devices, including virtual desktop terminals, IP turrets, compact switches, building management gateways, LED lights, wireless access points, and IP phones.
Tips:
In the newest Cisco Catalyst 9000 series switches family, there are Catalyst 9300 and 9400 can support UPoE while Catalyst 9200 only support PoE+.
See the datasheet:
Cisco Catalyst 9300 Switch Datasheet.pdf
Cisco Catalyst 9400 Switch Datasheet.pdf
Cisco Catalyst 9200 Switch Datasheet.pdf
Comparison of PoE, PoE+ and UPoE (PoE++)
Table 1. Comparison of PoE, PoE+ and UPoE.
| Property | PoE | PoE+ | UPoE |
| Power available at PD | 12.95 W | 25.50 W | 51W |
| Maximum power delivered by PSE | 15.40 W | 30.0 W | 60W |
| Minimum cable type | Category 3 | Category 5 | Category 5 |
Besides, there are other Comparison of PoE parameters.
Table 2. Comparison of PoE parameters.
| Property | 802.3af (802.3at Type 1) “PoE” | 802.3at Type 2 “PoE+” | 802.3bt Type 3 “4PPoE” | 802.3bt Type 4 |
| Power available at PD | 12.95 W | 25.50 W | 51 W | 71 W |
| Maximum power delivered by PSE | 15.40 W | 30.0 W | 60 W | 100 W |
| Voltage range (at PSE) | 44.0–57.0 V | 50.0–57.0 V | 50.0–57.0 V | 52.0–57.0 V |
| Voltage range (at PD) | 37.0–57.0 V | 42.5–57.0 V | 42.5–57.0 V | 41.1–57.0 V |
| Maximum current Imax | 350 mA | 600 mA | 600 mA per pair | 960 mA per pair |
| Maximum cable resistance per pairset | 20 Ω (Category 3) | 12.5 Ω (Category 5) | 12.5 Ω | 12.5 Ω |
| Power management | Three power class levels (1-3) negotiated by signature | Four power class level (1-4) negotiated by signature or 0.1 W steps negotiated by LLDP | Six power class levels (1-6) negotiated by signature or 0.1 W steps negotiated by LLDP | Eight power class levels (1-8) negotiated by signature or 0.1 W steps negotiated by LLDP |
| Derating of maximum cable ambient operating temperature | None | 5 °C (9 °F) with one mode (two pairs) active | 10 °C (20 °F) with more than half of bundled cables pairs at Imax | 10 °C (20 °F) with temperature planning required |
| Supported cabling | Category 3 and Category 5 | Category 5 | Category 5 | Category 5 |
| Supported modes | Mode A (endspan), Mode B (midspan) | Mode A, mode B | Mode A, mode B, 4-pair mode | 4-pair mode |
(Info: Power over Ethernet – Wikipedia)
If you have any different idea about PoE, please leave your comments.
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