The Cisco 100BASE-FX Small Form-Factor Pluggable (SFP) Fast Ethernet Interface Converter (GLC-GE-100FX=) is a hot-swappable device that plugs into a Gigabit Ethernet SFP port on Cisco Catalyst 3750 Series, 3560 Series, and 2970 Series switches. The Cisco SFP provides full-duplex 100-Mbps connectivity between switches over multimode fiber (MMF) infrastructures. It offers investment protection and an easy migration path for customers moving to Gigabit Ethernet connections in the future.The 100BASE-FX SFP operates on ordinary multimode fiber optical link spans of up to 2 kilometers in length. Customers implementing Cisco 100BASE-FX SFP can use 1000BASE-X SFPs in the future (including SX, LX/LH, ZX, and coarse wavelength-division multiplexing SFPs).