A standard LR module typically supports distances of up to 10km or 20km, though some extended LR variants (such as QSFP28-ER4 or QSFP-100G-ZR4-S modules) can reach 40km, 80km, or more depending on the specification. In reality, SFP transmission distance is defined by optical design—not data rate. An SFP (Small Form-factor Pluggable) module transmits data over fiber using specific wavelengths and power levels, which directly influence how far the signal can travel before degradation occurs. Common center wavelengths for gray optical modules include: 850 nm (with MMF): Can transmit up to 2 km at 100M rate, 550 m at 1G rate, 300 m at 10G rate, 400 m at 40G rate, and 100 m at 25G/100G/200G/400G rates. 1310 nm (with. Optical reach classifications provide a standardized framework for categorizing transceivers based on maximum transmission distance capabilities.
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