The QSFP28 LR4 transmits 100G over single-mode fiber using four wavelengths on the LAN-WDM grid: 1295.56nm, 1300.05nm, 1304.58nm, and 1309.14nm. Each lane carries 25G. The four lanes are multiplexed at the transmit side and demultiplexed at the receive side through an integrated LC duplex connector.
Key specs at a glance:
| Parameter | Value |
|---|---|
| Form factor | QSFP28 |
| Data rate | 100G (4 x 25G) |
| Wavelengths | 1295.56 / 1300.05 / 1304.58 / 1309.14nm |
| Fiber type | Single-mode (SMF) |
| Connector | LC duplex |
| Reach | 10KM |
| Transmit power (typical) | -4.3 to +4.5 dBm |
| Receive sensitivity | -10.6 dBm |
| Power consumption | Typically under 3.5W |
| Operating temperature | 0 to 70°C (commercial); -40 to 85°C (industrial variants) |
| Protocol support | 100GbE, OTU4, Fibre Channel 32G |
The 10KM reach puts LR4 squarely in the range for campus interconnects, inter-building links, and metro edge deployments—where SR4's 100M over OM4 falls short and ER4's 40KM is more than you need.
Several 100G QSFP28 variants exist in the market, and picking the wrong one is a common, expensive mistake.
SR4 uses four parallel 850nm lanes over multimode fiber, maxing out at 100M on OM4. It belongs inside a single data center row or pod. LR4 is single-mode, LC duplex, and rated to 10KM. If your link spans buildings or floors over existing SMF plant, LR4 is the right module.
CWDM4 also runs 10KM over SMF but uses a coarser wavelength grid—1271nm, 1291nm, 1311nm, 1331nm—versus LR4's LAN-WDM spacing. CWDM4 is common in hyperscale and open networking environments; LR4 is more prevalent in traditional enterprise and carrier-grade platforms. Check your switch's optics compatibility list before treating them as interchangeable.
ER4 extends reach to 40KM using the same LAN-WDM wavelengths as LR4, but with higher transmit power and an external FEC requirement on some platforms. For 10KM links, ER4 is over-engineered and more expensive. LR4 is the correct fit.
Compatible 100G QSFP28 LR4 modules work across all major platforms when properly programmed. Here's what matters per vendor.
Nexus 9000, Catalyst 9500, and ASR 9000 platforms all accept QSFP28 LR4. Cisco-compatible third-party modules must carry correct EEPROM programming to pass the platform's transceiver identification check—without it, the module may be blocked or throw an unsupported transceiver warning. Properly programmed compatible modules clear this check and run at full spec.
QFX and MX series platforms support QSFP28 LR4. Junos OS performs a transceiver ID check at insertion. Third-party modules programmed to Juniper's expected identifiers operate without the no-transceiver-check workaround that some vendors require.
Arista EOS platforms—including the 7050X and 7280 series—support QSFP28 LR4 natively. When the EEPROM is correctly populated, show interfaces transceiver will display full DOM data from compatible modules.
Huawei CE series switches and NE series routers accept QSFP28 LR4. Huawei platforms run vendor ID checks, so module programming must match the expected identifiers for the target platform.
The bottom line: compatibility is a programming question, not a hardware question. A well-sourced compatible module with correct EEPROM data performs identically to OEM on every platform above.
The most common use case. Two buildings connected by existing SMF conduit, distances from 500M to a few kilometers—LR4 handles this cleanly with margin to spare at its 10KM rated reach.
For short-haul DCI between colocation facilities or your own sites within a metro area, LR4 delivers a cost-effective 10KM solution without the complexity of coherent optics. Pair it with 100G QSFP28 DAC or AOC for intra-rack segments and use LR4 for the inter-site fiber runs.
ISPs running 100G aggregation between PoPs separated by 2 to 10KM use LR4 as a standard workhorse. The reach covers most metro PoP-to-PoP distances without amplification.
QSFP28 LR4 supports OTU4 framing, making it compatible with OTN muxponders and transponders. If your network runs an OTN overlay for traffic engineering or protection switching, verify OTU4 support in the module's datasheet before ordering—not all LR4 modules include it.
Cisco, Juniper, and Arista OEM 100G QSFP28 LR4 modules list at $200 to $500 or more per unit. Fully populate a 48-port 100G switch with LR4 at those prices and you're looking at $9,600 to $24,000 in optics alone.
Compatible third-party modules in this category deliver 70 to 90 percent cost savings against those OEM prices. On a 48-port deployment, the difference is large enough to fund additional switch hardware or move a capacity expansion forward on the timeline.
The cost argument sharpens at scale. A single module swap is a minor call. A 200-port rollout across multiple sites is a procurement decision that directly affects project ROI.
EEPROM programming for your target platform. This is the single most common source of compatibility issues. Ask the supplier whether the module is programmed for your specific switch vendor and model.
DOM support. Digital Optical Monitoring gives you real-time Tx/Rx power, temperature, and voltage readings through your switch's management interface. Confirm it before ordering.
Temperature rating. Commercial grade (0 to 70°C) covers standard data center environments. Outdoor cabinets and harsh industrial deployments need extended temperature variants.
Datasheet availability. Any credible supplier provides a product datasheet with transmit power range, receive sensitivity, extinction ratio, and compliance standards. No datasheet is a red flag.
Compatibility test evidence. Video-based testing showing the module operating in the target platform is the strongest pre-purchase proof available—it removes ambiguity that a spec sheet alone can't resolve.
HYTOPTODEVICE carries 100G QSFP28 LR4 modules compatible with Cisco, Juniper, Arista, and Huawei platforms, with compatibility test videos published on-site and product datasheets available for download. The catalog runs from 1.25G to 800G across every major form factor—SFP, SFP+, QSFP28, QSFP56, QSFP-DD, and OSFP—so if your network runs a mix of 10G, 100G, and 400G, you're sourcing from one supplier instead of managing multiple vendor relationships.
For teams with OEM or white-label requirements, the OEM/ODM program supports custom-programmed modules and branded production runs in the 100 to 1,000 unit range—a segment most commodity suppliers don't serve well.
What is the reach of a 100G QSFP28 LR4 transceiver?
The standard rated reach is 10KM over single-mode fiber. Real-world link budgets typically provide some margin beyond that depending on fiber quality and connector losses, but 10KM is the specified maximum.
Is QSFP28 LR4 compatible with QSFP+ ports?
No. QSFP28 and QSFP+ share a physical form factor but are electrically different. QSFP28 runs 4 x 25G lanes; QSFP+ runs 4 x 10G lanes. A QSFP28 LR4 module will not operate in a QSFP+ port.
Can I use a compatible third-party LR4 module in a Cisco Nexus 9000?
Yes, provided the module is correctly programmed with Cisco-compatible EEPROM identifiers. Properly programmed compatible modules pass Cisco's transceiver identification check and operate at full spec with DOM support active.
What fiber and connectors does QSFP28 LR4 use?
LR4 uses LC duplex connectors on single-mode fiber (OS1 or OS2). It does not work on multimode fiber or with MPO connectors.
What is the difference between LR4 and CWDM4 at 100G?
Both run 10KM over SMF using four wavelengths, but on different grids. LR4 uses the LAN-WDM grid (approximately 1295 to 1310nm); CWDM4 uses a coarser grid (1271 to 1331nm). They are not interoperable at the optical layer. Your platform's compatibility list will specify which variant each switch supports.
Does 100G QSFP28 LR4 support OTN framing?
Yes. LR4 modules with OTU4 support are available and used in OTN muxponder and transponder applications. Verify OTU4 support in the product datasheet—not all LR4 modules include it.
How much can I save by using compatible LR4 modules instead of Cisco OEM?
Cisco OEM 100G QSFP28 LR4 modules are typically priced at $200 to $500 or more per unit. Compatible alternatives deliver 70 to 90 percent cost savings against those OEM prices—on any multi-port deployment, that adds up fast.
The 100G QSFP28 LR4 is a mature, well-understood module, but buying it wrong still costs money. Get the platform programming right, confirm DOM support, and source from a supplier who publishes datasheets and compatibility evidence. For the full catalog and compatibility test videos, visit hytoptodevice.com.
