UniFi Switch 48 750W

Ubiquiti · rack switch, 1U · US-48-750W

what it is

A managed switch for a 19-inch rack, 1U high: forty-eight gigabit ports with PoE, two SFP+ 10 Gb/s transceiver slots and two SFP 1 Gb/s slots. Steel enclosure, 444 × 374.6 × 43.7 mm — deeper than most 1U equipment, which needs to be checked before ordering for a wall-mounted rack.

Each access port delivers up to 34.2 W under the PoE+ standard, and additionally supports passive 24 V power up to 17 W.

The power budget is a ceiling, not a number to divide — and this is the core of this device:

The difference is more than two and a half times. In practice this means that filling all ports with high-draw devices is impossible, and the switch will start refusing power to further ones — usually the ones connected last. The symptom then looks like a failure of the most recently connected device, not like power exhaustion, and this is the most common mistake with this model.

The budget figure itself also requires caution: the manufacturer states it differently in two places — 750 W in one document and 686 W in another. For planning, the lower one counts, because an error on the optimistic side costs a powered-off device.

On the rear panel there is an AC power inlet rated up to 9 A and a management port, which the manufacturer does not count in the port numbering.

what we read from it

The state of each of the fifty-two ports separately, and for the forty-eight access ports also power draw.

• PoE draw per port and the total for the device. With this model this is not a curiosity but the number that decides whether the next device will come up at all. A total approaching the budget is a warning that precedes a failure.
• Negotiated speed, separately from what the port is capable of.
• Counters of errored frames, discards and link drops on every port.
• Spanning tree changes — on an access switch of this size usually the first sign of a loop someone plugged into a free port.
• The number of MAC addresses seen on a port and what is visible on the other end of the cable.
• Power mode and power class drawn on each PoE port.
• Port assignment to VLANs and the link quality rating reported by the device itself.
• Internal temperature from the on-board sensor. With forty-eight PoE ports in a 1U enclosure, this is a number worth trending.

port layout

The forty-eight copper ports sit in two rows of twenty-four, divided into blocks. Numbering runs down, then right: 1, 3, 5… on top and 2, 4, 6… on the bottom.

The four fiber slots are at the right edge, in two pairs: first two SFP+ 10-gigabit ones (49 and 50), followed by two SFP 1-gigabit ones (51 and 52). These two pairs look identical and differ only in throughput — a ten-gigabit transceiver inserted into port 51 will work, but at gigabit speed.

At the left edge of the panel there is an illuminated field with the manufacturer's logo that signals the device state. On the rear panel: the power inlet and the management port.

what to watch out for

• The fan level from the controller does not tell you whether the fans are spinning. For the whole first generation of UniFi switches the controller reports level 0 regardless of temperature.
• There is no cable test. The UniFi Network 10.6.106 controller has no such function at all.
• SNMP will not report PoE draw. The standard PoE table is empty; per-port draw is reported only by the controller. The switch silently truncates an SNMP community string longer than 20 characters.

what we cannot read

• The actual power ceiling at a given moment — the total draw and the datasheet budget are known, but not how much the switch is willing to deliver at the current temperature and voltage.
• PoE draw history over time at the level of a single port.
• Fan speed — there is internal temperature, not fan speed.

transceivers tested in this device

Transceivers we checked in this device, and whether the device showed their optical diagnostics (temperature, power, alarm thresholds):

• Unbranded GLC-LH-SM (1000BASE-LX/LH), firmware 7.4.1.16850: diagnostics read (1 units).
• Ubiquiti OM-SM-10G-D (10GBASE-LR), firmware 7.4.1.16850: diagnostics read (1 units).
• Ubiquiti UF-MM-10G (10GBASE-SR), firmware 7.4.1.16850: diagnostics read (2 units).
• Ubiquiti UF-SM-10G (10GBASE-LR), firmware 7.4.1.16850: diagnostics read (1 units).
• Ubiquiti UDC-2 (10G SFP+ Direct Attach, passive), firmware 7.4.1.16850: diagnostics not shown (1 units).

All transceivers and switches in one place, with filters: what each device shows.

full list of parameters read via SNMP

These are objects the device itself returns over SNMP (names from MIB files). There are no values here, and no port numbers either.

100 parameters

SNMP list source: reading of 1 unit (as of 2026-10-18).