In 10G Ethernet deployment, SFP-10G-SR and SFP-10G-LRM are two widely used short-distance optical modules. Although they have similar names and both use SFP+ packaging and LC interfaces, they have essential differences in fiber compatibility, transmission mechanism and applicable scenarios, which directly affect the cost and performance of network construction.
Contents
Core Parameter Comparison
| Features | SFP-10G-SR | SFP-10G-LRM |
| Wavelength | 850 nm | 1310 nm |
| Fiber type | Multimode fiber (MMF) | Multimode fiber (MMF) or single mode fiber (SMF) |
| Maximum transmission distance | OM3: 300m; OM4: 400m | MMF: 220m; SMF: 300m |
| Fiber compatibility | OM3/OM4 optimized, OM1/OM2 only supports 33m | Compatible with OM1/OM2 (220m) |
| Special requirements | No | mode adjustment jumper required (OM1/OM2) |
Physical layer differences
SR module uses VCSEL laser (850nm), which is designed for multimode fiber and uses the wide core diameter of the fiber to achieve short-distance high-speed transmission; LRM module uses DFB laser (1310nm) to eliminate the modal noise of multimode fiber through electronic dispersion compensation technology, thereby achieving longer distances on old optical fibers.
Legacy fiber adaptability
SFP-10G-SR only supports 33 meters on OM1/OM2 fiber, which basically cannot meet the actual deployment requirements.
SFP-10G-LRM compensates for modal dispersion through mode conditioning cable, and can stably transmit 220 meters on OM1/OM2 fiber, making it an ideal choice for upgrading old equipment rooms.
Differences in Deployment Requirements
Necessity of mode conditioning cable
When the LRM module is connected to OM1/OM2 fiber, a mode conditioning cable must be used to avoid signal distortion caused by modal dispersion.
If OM3/OM4 fiber is used, no additional jumper is required.
Optical power management
The optical power at the receiving end of the LRM module must be higher than -6.5dBm but not more than 0.5dBm. If the input optical power is detected to be >0.5dBm, a 5dB attenuator must be inserted at both ends of the link to prevent receiver saturation.
Application Scenario Selection Guide
Choose SFP-10G-SR when:
The network uses OM3/OM4 multimode fiber (such as a new data center);
The transmission distance is ≤300 meters and low cost and low power consumption are pursued (typical power consumption is 0.6W);
High-density cabinet interconnection is required (such as server-switch short-distance connection).
Choose SFP-10G-LRM when:
There are old OM1/OM2 multimode fibers that need to be reused (such as enterprise computer room renovation);
Need to transmit ≤300 meters on single-mode fiber (compatible with dual-mode flexible deployment);
Span 220-300 meters multimode environment (SR cannot cover).
Economic tips: The unit price of LRM modules is usually higher than SR (about 20%~30%), but its compatibility with old fibers can save overall wiring costs.
Conclusion: Accurate Matching of Scenarios is the Key
SFP-10G-SR is a cost-effective solution for short-distance transmission of modern multimode optical fibers, while SFP-10G-LRM has become a technical bridge for transformation projects with its multimode/single-mode dual compatibility and old optical fiber adaptation capabilities. When making decisions, it is necessary to give priority to evaluating the type of optical fiber in the existing network and the distance requirements: if it is OM3/OM4 and the distance is <300 meters, SR is an efficient choice; if it faces OM1/OM2 or requires cross-mode flexibility, LRM will provide a more reliable solution.
