1000BASE-LX is a Gigabit Ethernet optical standard defined under IEEE 802. 3, designed for long-wavelength transmission over fiber. However, many engineers and buyers still have practical questions: What exactly does “LX” mean in SFP modules? How does it compare with LR, LH, or SX. The industry-standard Cisco Small Form-Factor Pluggable (SFP) Gigabit Interface Converter (Figure 1) links your switches and routers to the network. It operates at a 1310nm wavelength and is widely used in enterprise, campus, and access networks where copper cabling or short-reach multimode optics are no. AXIS T8611 SFP Module LC. Long-distance variants, typically referred to as LX, EX, ZX, or ER/LR SFPs, are engineered with higher optical power budgets and longer wavelength.