The Dell D0R73 is a 2-metre 25GBASE-CR passive direct attach twinax cable terminated with a fixed SFP28 connector at each end, rated for 25 Gbps per lane. It is Dell's DAC-SFP-25G-2M and it is the cheapest correct way to link two SFP28 ports inside the same rack.
Where it belongs
Passive copper is the right medium for the shortest connections in a data centre - a top-of-rack switch down to servers in the same cabinet, or a pair of switches stacked for redundancy. There is no transceiver electronics inside a passive DAC, so it draws no power, adds no latency budget of its own and cannot fail in the way an optic can. Against a 25GbE SR optic pair plus fibre, a 2 m DAC is a fraction of the cost and a fraction of the parts count.
Two metres is the working length for a switch-to-server hop within one rack. If the run crosses cabinets, step up to the 3 m or 5 m part; if it leaves the row, you want optics and fibre instead.
FEC behaviour
Dell's transceivers and cables spec sheet notes that the 1, 2 and 3 m lengths of the 25G DAC family can operate without FEC. That matters when you are cabling into a switch or NIC whose forward error correction settings you would rather not touch - at 2 m you have the option. The 5 m part does not give you that latitude.
Which switches take it
Any Dell switch with SFP28 ports: the S5048F-ON, S5148F-ON, S5224F-ON, S5248F-ON and S5296F-ON in the data centre line, and the N2248X-ON, N3248X-ON and N3248PXE-ON on the campus side. A 100GbE QSFP28 port can also feed four SFP28 lanes, but that needs a breakout cable rather than this one - see the 100G-to-4x25G breakout parts.
Condition
Refurbished, tested and covered with warranty. Passive copper assemblies have no active components to degrade, which is why a tested used DAC behaves identically to a new one.
Related models
Specifications
| Dell model designation | DAC-SFP-25G-2M |
|---|---|
| Standard | 25GBASE-CR (SFP28 direct attach copper) |
| Cable length | 2 m (6.5 ft) |
| Connector | SFP28 to SFP28 |
| Transmission medium | Passive copper twinax |
| Data rate | 25 Gbps per lane |
| Power dissipation | None - passive assembly, no transceiver electronics |
| FEC | 2 m can operate without FEC |
| Shipping weight | 1.0 lbs |
