UniFi Switch 48

Ubiquiti · rack switch, 1U · US-48

what it is

A managed switch for a 19-inch rack, 1U high: forty-eight gigabit ports, two SFP+ 10 Gb/s transceiver slots and two SFP 1 Gb/s slots. Steel enclosure, 443 × 286 × 43 mm, weighing 3.56 kg.

No port delivers PoE — and this is not an omission in the datasheet. The manufacturer does not list PoE anywhere in the specification, and there is not a single power mark next to the port numbers on the front panel. This is a device for dense office cabling, where access points and cameras hang off a separate switch with a power budget.

Its own consumption is up to 56 W — that is how much the switch itself needs to operate. For comparison, the PoE counterpart from the same family draws a dozen or so times as much and is half again as heavy.

Cooling is active: two fans on the rear panel. The manufacturer gives two noise levels — 0.7 dBr and 13.5 dBr — so fan speed is regulated and the device is quiet under light load. The rear panel also has a console port, which the manufacturer does not count in the port numbering.

Watch the name. US-48 is not a variant of the US-48-750W. They are separate devices: a different enclosure (443 × 286 mm versus 485 × 374.6), a different weight (3.56 kg versus 8.5) and an entirely different purpose — that one has forty-eight PoE ports and a power budget, this one has no PoE at all.

what we read from it

The state of each of the fifty-two ports separately.

• Negotiated speed, separately from what the port is capable of.
• Counters of errored frames, discards and link drops on every port. With forty-eight access ports this is the only practical way to find a single faulty cable run without walking around the office.
• Spanning tree changes — on a 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.
• Port assignment to VLANs and the link quality rating reported by the device itself.
• Uptime, availability and response latency.
• Internal temperature from the on-board sensor — as across the whole first generation of UniFi switches except the fanless models and the Lite series.

port layout

The forty-eight copper ports sit in two rows of twenty-four, divided into four blocks of six columns. Numbering runs down, then right: 1, 3, 5… on top and 2, 4, 6… on the bottom. Column spacing is even across the whole panel, including between blocks.

At the right edge there are two fiber cages, each with two ports stacked one above the other: the left one is SFP+ 10 Gb/s (ports 49 and 50), the right one SFP 1 Gb/s (51 and 52). The cages 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 there is an illuminated field with the manufacturer's logo that signals the device state, and at the right edge — the reset pinhole. Each port has two LED windows: speed and activity.

On the rear panel, from the left: console port, fan, a small DC input jack, the second fan and the AC power inlet.

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. Cooling is indicated by the internal temperature.
• There is no cable test. The UniFi Network 10.6.106 controller has no such function at all.
• The switch silently truncates an SNMP community string longer than 20 characters — it then responds only to the first 20 characters and stays silent for the full string.

what we cannot read

• PoE — the device does not have it. This is a hardware limit.
• Fan speed — there is internal temperature, not fan speed.
• Fiber transceiver state — neither optical signal level nor module temperature.

transceivers tested in this device

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

• E2O Communications ES212-LP3TA-A-F1 (1000BASE-LX; Fibre Channel 1/2G LW), firmware 7.5.15.17146: 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.

104 parameters

SNMP list source: reading of 2 units (as of 2026-10-18).