Dell PowerSwitch S3248T-ON 1GbE Switch

The Dell PowerSwitch S3248T-ON is a 1RU data-centre management switch with 48 auto-sensing 10/100/1000Mb RJ45 ports, four 10GbE SFP+ uplinks and two 100GbE QSFP28 uplinks, running Dell SmartFabric OS10 on a non-blocking fabric that forwards at 800 Mpps.

It exists for one job: terminating the out-of-band management network. Every iDRAC, every BMC, every PDU, every console server and every serial concentrator in a row of racks lands on a switch like this one, and the reason it has 100GbE uplinks is that the management network in a modern data centre is no longer an afterthought hanging off a spare port.

What an out-of-band management switch actually has to do

Out-of-band management is the network you use when the production network is down. That is the whole premise, and it dictates the requirements.

The endpoints are almost universally 1GbE copper - server BMC and iDRAC ports, storage-controller management interfaces, switch management ports, intelligent PDUs, environmental sensors, terminal servers. There are a lot of them: one or two per server, plus one per network device, plus infrastructure. Forty-eight ports of 1GbE copper in one rack unit is exactly the right shape, and no amount of multigig would help because a BMC will never do more than a gigabit.

What does matter is that the management network stays reachable when everything else is not, which is why this switch is built like production kit rather than like a utility box: non-blocking Layer 2 and Layer 3 at line rate, dual firmware images on-board, an optional second hot-swappable power supply, redundant variable-speed fans, and MLAG so a pair of these can present active/active uplinks with firmware upgrades that do not take the management plane offline. If you have ever had to physically walk to a data centre because the management switch rebooted during a firmware update, that last point is the whole argument.

Why the uplinks are 100GbE on a 1GbE switch

Forty-eight gigabit ports is 48 Gbps of access bandwidth, and four 10GbE uplinks would carry it comfortably. So the two 100GbE QSFP28 ports are not there for the access traffic - they are there so the management switch can attach directly to the same spine as everything else, at the same speed, using the same optics and the same cables.

That matters more than it sounds. It means the management network is not a second-class fabric with its own aggregation switches and its own optics inventory; it plugs into the leaf-spine you already have. It also means the OOB switch can carry image-deployment and telemetry traffic - PXE and bare-metal provisioning, streaming telemetry, log and metric export - without a bandwidth conversation, which is increasingly how large fleets are actually built.

Dell describes both QSFP28 ports as uplinks. This is not a stacking switch, and that is the single most important difference between it and its campus lookalike, the N3248TE-ON, which has a near-identical front panel but uses its two 100GbE ports as a 400 Gbps stack interconnect and runs the campus OS6 instead of OS10. If you are comparing the two, the question is not which has better specs - it is which network you are building.

AI and GPU clusters made this a bigger deal than it used to be

Dell lists the S3248T-ON under both its data-centre switch range and its AI switch range, and the second listing is not marketing filler. A GPU cluster has an unusually heavy management footprint: every node has a BMC, and on top of that sit fabric managers, telemetry collectors, power and thermal monitoring, and out-of-band paths to the accelerator fabric itself. The nodes are dense, the power draw is high, and the cost of a node being unreachable is measured in idle GPU hours.

The practical consequence is that AI build-outs specify a proper OOB switch per row rather than borrowing ports, and they specify one with real uplinks because provisioning images across a cluster is a bandwidth event. That is the shape of this switch.

SmartFabric OS10 and SONiC

The S3248T-ON runs Dell SmartFabric OS10, and Dell also lists Enterprise SONiC Distribution by Dell Technologies as a supported software configuration. This is a data-centre operating system, not the campus OS6 that the N-series runs - the CLI, the automation model and the feature set all belong to the S- and Z-series world.

That brings VXLAN support, Advanced Layer 3 with BGP, VRF and VRF Lite, BFD, PIM-SSM, IGMP and OSPFv2/v3, and an OpenConfig gNMI interface for system management. gNMI is worth calling out specifically: if your fleet is managed by streaming telemetry and model-driven configuration rather than by SSH and expect scripts, this switch speaks that language natively. VRF Lite is the other feature that gets used constantly here, because it lets one physical management switch carry several isolated management domains - tenant, infrastructure, and vendor-access - with separate control and data planes.

A Dell software entitlement is bound to the unit's service tag and to a Dell account and does not automatically transfer on the secondary market. A refurbished unit may arrive with a working OS10 image installed and without an active entitlement or support contract. We do not promise a transferred Dell licence, a software subscription or a support contract with a refurbished switch. Tell us what you intend to run and we will confirm the state of a specific unit before it ships.

Airflow, and why it matters more here than usual

Dell builds the S3248T-ON with either Normal airflow (I/O Panel to PSU) or Reverse airflow (PSU to I/O Panel), and offers the power supply and the fan module in both directions.

Management switches are unusually likely to need the reverse direction. They tend to be mounted at the top or bottom of a rack facing whichever way the copper is easiest to dress, which is frequently the opposite of the production switch two rack units above. Mixing directions inside one rack is a common and entirely avoidable cause of a switch running hot. Confirm the direction you need when you request a quote - the power supply and fan are direction-specific parts, so this is decided at build time rather than in the rack.

Common questions

Can I stack two S3248T-ON switches?

No. Dell describes the two 100GbE QSFP28 ports as uplinks, not stacking ports. For high availability, pair two switches with MLAG - that gives you active/active uplinks and lets you upgrade firmware on one without taking the management plane down.

How is this different from the N3248TE-ON, which looks identical?

Same port count and nearly the same front panel, opposite jobs. The N3248TE-ON is a campus switch running OS6 with 400 Gbps of stacking across those 100GbE ports. The S3248T-ON is a data-centre switch running SmartFabric OS10 with those ports as uplinks, plus a much larger 16GB of CPU memory and an OpenConfig gNMI interface. Campus versus data centre, not better versus worse.

Does it do PoE?

No. If you need PoE on a 48-port 1GbE switch, look at the campus range instead - the N1148P-ON at the entry level, or the N3248PXE-ON for 802.3bt up to 90W.

Is 48 Gbps of access against 288 Gbps of fabric oversubscribed?

The opposite. Dell states line-rate non-blocking Layer 2 switching and line-rate non-blocking Layer 3 routing on all ports. The fabric is sized for the uplinks, not the access ports.

Where it sits against the rest of the range

Availability, condition and how to buy

This model is supplied to order. Availability, airflow direction, power-supply count and optics loadout are confirmed at quotation, so use the quote request on this page and tell us what the row needs.

Every unit is refurbished, professionally reconditioned, powered up, inspected and functionally tested before it ships, and it ships with warranty coverage. If you need a specific OS10 or SONiC state, or a matched pair for an MLAG domain, say so with your request.

Specifications