25G has quietly become the default starting point for new server and switch access ports — not because 100G isn’t available, but because 25G SFP28 delivers 2.5x the bandwidth of 10G SFP+ in the exact same physical form factor, over the same fiber types, often without re-cabling a rack. Here’s what a 25G SFP module actually is, how to choose between the common variants, and which brands NextGen Networks carries them in.
What Is a 25G SFP Transceiver?
A 25G SFP transceiver — technically called SFP28 — is a hot-pluggable optical or copper module delivering 25 Gigabit Ethernet over a single lane. It’s mechanically the same size as a 1G SFP or 10G SFP+ module, which is the whole point: a switch or NIC can move from 10G to 25G without a chassis redesign, and in many cases a 25G SFP28 port will auto-negotiate down to run existing 10G SFP+ modules during a phased upgrade.
25G SFP28 also matters beyond standalone 25G links — it’s the building block for 100G. Four 25G lanes combine to form a 100G QSFP28 connection, which is why 25G has become the standard server-to-switch speed underneath 100G spine-leaf fabrics.
SR, LR, and the Other Common Variants
Like the 10G and 40G families before it, 25G SFP28 modules split primarily by fiber type and reach:
25GBASE-SR (multimode, short reach). Uses an 850nm laser over multimode fiber with a duplex LC connector, typically reaching up to 70m on OM3 and 100m on OM4 fiber. This is the most common 25G module for in-rack and in-building server/switch links.
25GBASE-LR (single-mode, long reach). Uses a 1310nm laser over standard single-mode fiber, typically reaching up to 10km, with a duplex LC connector — the default choice once a link crosses buildings or exceeds multimode’s range.
Extended-reach and multirate variants. Several vendors also offer extended-reach (“ER”-labeled) and multirate (“MR”-labeled) 25G SFP28 modules. MR variants generally support dual-rate operation (commonly 10G and 25G on the same module), which is useful for simplifying spares during a phased 10G-to-25G migration. Because these naming conventions vary slightly by manufacturer, always confirm exact reach and rate-support figures against that vendor’s own datasheet before ordering.
Direct-attach copper (25G DAC). For very short in-rack runs, a passive or active copper cable assembly is often more cost-effective than a transceiver-plus-patch-cable setup.
Quick Reference
| Type | Fiber | Wavelength | Typical Reach | Connector |
| 25GBASE-SR | Multimode | 850nm | 70m (OM3) / 100m (OM4) | Duplex LC |
| 25GBASE-LR | Single-mode | 1310nm | 10 km | Duplex LC |
| 25G DAC | Copper (direct-attach) | — | A few meters | Built-in |
Extended-reach and multirate variants vary by brand — confirm the specific datasheet before relying on exact figures.
25G SFP Brands Available at NextGen Networks
NextGen Networks stocks verified 25G SFP28 product lines across five brands:
- Aruba / HPE — including SFP-25G-SR, SFP-25G-LR, and multirate variants (SFP-25G-MR-SR, SFP-25G-MR-LR, SFP-25G-MR-XSR), plus BiDi and FN-TRAN-SFP28 options
- Ruckus — E25G-SFP28-SR and E25G-SFP28-LR
- Palo Alto Networks — PAN-SFP28-25GBASE-SR/LR, with TAA-compliant PAN-T-S28 variants
- NVIDIA Mellanox — a broader range including the MC2210411 and MC2210511 series, built for GPU cluster and high-performance server connectivity
- Finisar / II-VI — SFP-25G-SR/SR-E, SFP-25G-LR/LR-E, SFP-25G-ER, and multirate MR-SR/MR-LR/MR-XSR options
If your firewall, switch, or server platform is built on one of these brands, matching the part number to your platform’s supported-optics list is the first step before choosing between SR, LR, or a multirate variant. For firewall-specific guidance, see our Palo Alto transceiver buying guide.
25G SFP28 vs. 10G SFP+: Do You Need to Upgrade?
Not every network needs 25G today. A few signals that it’s worth considering:
- Your switches and NICs already support SFP28 ports (many do, even if currently populated with 10G SFP+ modules)
- You’re running out of headroom on existing 10G server uplinks
- You’re building toward a 100G spine-leaf fabric, where 25G is the native server-facing speed
- You want to future-proof new cabling runs without paying for 100G hardware you don’t need yet
If none of these apply, there’s no urgency to replace working 10G infrastructure — 25G SFP28’s main advantage is at the point of a planned refresh, not as a forced mid-cycle swap. If you’re still deciding whether 10G meets your needs, see our Cisco SFP+ 10G transceiver guide for a full breakdown of that tier.
Buying Considerations
Match fiber type first. As with every speed tier before it, SR needs multimode and LR needs single-mode — they aren’t interchangeable.
Check your platform’s supported-optics list. 25G SFP28 support and exact part-number compatibility vary by switch, NIC, or firewall model — confirm before ordering, especially across brands like Palo Alto and Aruba where TAA-compliant and standard variants both exist.
Consider multirate (MR) modules for phased migrations. If some links will stay at 10G longer than others, a dual-rate module can reduce how many separate part numbers you need to stock.
Don’t assume auto-negotiation works everywhere. Whether a 25G SFP28 port accepts a 10G SFP+ module varies by platform — check your hardware’s documentation rather than assuming universal backward compatibility.
Use DAC for very short runs. Within or between adjacent racks, a 25G direct-attach cable is often the simplest and most cost-effective option.
Frequently Asked Questions
What is the difference between SFP+ and SFP28? SFP+ is the 10G form factor; SFP28 is mechanically the same size but built for 25G, with enhanced electrical specifications to support the higher signaling rate.
Can a 25G SFP28 module work in a 10G SFP+ port? Not generally — a 25G module requires a port that supports 25G signaling. Some multirate (MR) modules support both 10G and 25G, but the port itself still needs to support the rate in question.
What’s the reach difference between 25G SR and LR? SR is a multimode module reaching up to 100m on OM4 fiber. LR is a single-mode module reaching up to 10km. They use different fiber types and aren’t interchangeable.
Is 25G SFP28 the same thing as 100G? No, but they’re related — four 25G SFP28 lanes combine to form a 100G QSFP28 connection, which is why 25G is the standard building block underneath many 100G fabrics.
Do I need to replace all my 10G infrastructure to move to 25G? No. Many organizations migrate gradually, often using multirate (10G/25G) modules to simplify sparing during the transition rather than replacing everything at once.
Which brands of 25G SFP28 does NextGen Networks supply? Aruba/HPE, Ruckus, Palo Alto Networks, NVIDIA Mellanox, and Finisar/II-VI, across SR, LR, and several multirate and extended-reach variants.
Sourcing 25G SFP Transceivers
NextGen Networks supplies genuine 25G SFP28 transceivers across Aruba, Ruckus, Palo Alto Networks, NVIDIA Mellanox, and Finisar/II-VI — and can help confirm which SR, LR, or multirate module matches your specific switch, firewall, or server platform before you order. For 100G and 400G fabrics that 25G links feed into, see our Cisco 400G and 800G optics guide and our Finisar 400G optical transceivers page.
Conclusion
25G SFP28 has become the practical default for server and switch access ports heading into 2026 — it reuses the same compact form factor as 10G SFP+, supports both multimode and single-mode fiber depending on reach, and serves as the literal foundation for 100G fabrics via 4x25G breakout. Matching fiber type and reach to your actual link, and confirming platform support for your chosen brand and part number, covers nearly every buying decision in this category.
