The SFP 1G LX runs at 1.25G line rate over single-mode fiber using a 1310nm laser. Standard reach is 10KM on SMF. The form factor is standard SFP — not SFP+ — and the module is hot-swappable.
| Parameter | Value |
|---|---|
| Data rate | 1.25G (1G Ethernet) |
| Wavelength | 1310nm |
| Fiber type | Single-mode (SMF) |
| Max reach | 10KM |
| Connector | LC duplex |
| Transmit power (typical) | -9.5 to -3 dBm |
| Receive sensitivity | -20 dBm or better |
| Power consumption | Under 1W typical |
| Standard | IEEE 802.3z 1000BASE-LX |
The 1000BASE-LX standard also supports multimode fiber at reduced reach — up to 550M on 50/125 OM3 with a mode conditioning patch cable. If you are running MMF at shorter distances, confirm your module supports that requirement, or source a 1000BASE-LX/LH variant that handles both fiber types.
This is where most procurement decisions stall. OEM modules are programmed with vendor-specific EEPROM data that passes the switch's compatibility check. Third-party modules must replicate that programming accurately, or the switch will reject the module outright or log a warning that some teams treat as a hard blocker.
Cisco's 1G LX OEM part is the GLC-LH-SMD — the updated version of GLC-LH-SM. It runs on Catalyst 2960, 3560, 3750, 4500, 6500, and Nexus 2000 FEX platforms, among others. IOS and IOS-XE will flag non-Cisco modules unless service unsupported-transceiver is configured, which is standard practice in most shops running third-party optics.
Compatible GLC-LH-SMD replacements need to match the EEPROM identifier, vendor name field, and part number encoding that Cisco's software checks. Modules that do this correctly run without alarms.
Juniper's equivalent is the SFP-1GE-LX. EX-series and QFX access switches accept third-party SFPs without a CLI unlock command on most firmware versions, making Juniper one of the more permissive platforms for compatible optics. That said, verify the EEPROM encoding matches Juniper's expected fields to avoid DOM reporting gaps.
Huawei's 1G LX SFP (SFP-GE-LX-SM1310) is used across S-series campus switches and AR-series routers. VRP firmware checks the vendor OUI in the EEPROM. Third-party modules programmed for Huawei compatibility need the correct OUI and part number, or the port will come up but generate a transceiver alarm in the NMS.
Arista EOS accepts third-party optics by default on most platforms. The show interfaces transceiver output will display DOM data if the module supports it. For 1G LX, Arista compatibility is generally straightforward with any well-programmed third-party module.
For customers and buyers, optical module compatibility is of critical importance; it directly determines the success of link connections, the smoothness of communication, and the assurance of communication quality. Furthermore, given the vast array of switches on the market—featuring diverse technical specifications and application scenarios—it is difficult to guarantee the quality of optical module supplies without dedicated research and appropriate strategies. HYTOPTODEVICE do well in compatibility about optical transceivers.
If you are sourcing 1G SFPs and see LX, LX/LH, and SX in the same catalog, here is the practical difference:
For fiber runs under 10KM on SMF, standard 1G LX covers every case. Runs between 10KM and 40KM may need an LX/LH or EX variant — check the reach spec on the datasheet before ordering.
Some switch firmware versions enforce stricter EEPROM checks than others. Confirm the module you are sourcing has been tested against your specific platform and IOS/EOS/VRP version. Compatibility test videos and datasheets are the fastest way to verify this without pulling a lab switch.
Most 1G LX modules support Digital Optical Monitoring, but not all third-party modules implement it fully. If your NMS relies on DOM data — Tx power, Rx power, temperature, voltage, bias current — confirm the module reports all five parameters correctly.
SFP 1G LX modules use LC duplex connectors. Confirm your patch panel and fiber plant use LC connectors with matching UPC or APC polish. Mixing APC and UPC on the same link introduces insertion loss that will degrade your link budget.
Standard commercial-grade modules are rated 0 to 70°C. Deploying in an industrial environment, outdoor cabinet, or any location that exceeds that range requires an industrial-grade module rated to -40 to 85°C. Do not assume a commercial module will hold spec at temperature extremes.
Standard 1G LX uses dual fiber — separate Tx and Rx strands. If your fiber plant is single-fiber, you need a 1G BiDi SFP, not an LX module. These are different products with different wavelength pairs.
Cisco's GLC-LH-SMD lists at over $200 through authorized channels. Juniper and Huawei OEM equivalents sit in a similar range. Third-party compatible 1G LX modules deliver the same 1310nm, 10KM, LC duplex spec at 70 to 90 percent less.
For a network with 50 access switches each needing two uplink SFPs, that difference adds up fast. The compatibility concern that once justified OEM pricing has largely been addressed by suppliers who program modules specifically for each target platform and publish test results to back it up.
The risk is not in buying third-party. The risk is buying from a supplier who does not test against your specific platform and cannot show you the evidence.
HYTOPTODEVICE carries SFP 1G LX modules compatible with Cisco, Juniper, Huawei, and Arista platforms, with compatibility test videos and product datasheets available on-site before you commit. The catalog runs from 1.25G to 800G across every major form factor, so if your network also runs 10G, 100G, or 400G uplinks, you can consolidate sourcing across SFP, SFP+, QSFP28, QSFP-DD, and more in one place.
For teams with OEM or white-label requirements, custom-programmed SFP modules are available through the OEM and ODM program — covering modules pre-programmed for a specific platform, branded for resale, or built to a custom EEPROM spec for application-specific deployments. Your brand, our engineering.
In addition to above, HYTOPTODEVICE provides private labeling and package.We maintain strong partnerships with logistics providers worldwide, offering significant advantages in terms of time and cost savings.
HYTOPTODEVICE offers significant lead time and support advantages. Thanks to our self-sufficient core material supply, continuous component inventory, and robust manufacturing capacity, we guarantee exceptionally fast delivery, with standard products shipping within 2 to 3 days. Furthermore, we provide immediate remote technical guidance to resolve compatibility issues on the spot, backed by our specialized re-coding boxes and software for instant, on-site firmware adjustments.
Q1:What is the reach of an SFP 1G LX transceiver?
A:Standard 1G LX reach is 10KM over single-mode fiber at 1310nm. Some LX/LH variants extend this to 20KM or 40KM at higher transmit power. Always confirm the datasheet for the specific module you are sourcing.
Q2:Will a third-party SFP 1G LX work in a Cisco Catalyst switch?
A:Yes, with correct EEPROM programming and the service unsupported-transceiver command configured on the switch. Third-party modules that accurately replicate Cisco's EEPROM fields operate without alarms or performance degradation.
Q3:Can I use a 1G LX SFP on multimode fiber?
A:Yes, but only up to 550M on 50/125 OM3 fiber, and you typically need a mode conditioning patch cable to avoid modal noise issues. Beyond 550M, you need single-mode fiber or a different module type.
Q4:What is the difference between 1G LX and 1G LX/LH?
A:LX is the base 10KM spec at 1310nm. LX/LH covers both the standard 10KM reach and extended reach up to 40KM depending on the variant. Cisco's GLC-LH-SMD is an LX/LH module. For most 10KM deployments, either designation works.
Q5:Does a 1G LX SFP support Digital Optical Monitoring?
A:Most do, but implementation varies. Full DOM support covers Tx power, Rx power, temperature, supply voltage, and bias current. Check the datasheet for all five parameters if your NMS depends on DOM data for link health monitoring.
Q6:What connector type does a 1G LX SFP use?
A:LC duplex. Both transmit and receive fibers terminate in a single LC duplex connector on the module side. Confirm your patch cables and panel connectors match before deployment.
Q7:How do I know if a compatible SFP 1G LX has been tested on my platform?
A:Ask the supplier for a compatibility test video or datasheet that names your specific switch model and firmware version. If they cannot provide that, they should not be your first choice for production network hardware.
The SFP 1G LX is a mature, well-understood product. Your buying decision in 2026 comes down to three things: the right reach variant for your fiber plant, confirmed compatibility with your switch platform, and a supplier who can prove it. ISP-grade optics without the OEM markup are available — you just need to source from someone who tests before they ship.
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