The Cisco industry-standard Small Form-factor Pluggable (SFP) Gigabit Interface Converter is a hot-swappable input/output device that plugs into a Gigabit Ethernet port or slot, linking the port with the network. SFPs can be used and interchanged on a wide variety of Cisco products and can be intermixed in combinations of 1000BASE-SX, 1000BASE-LX/LH, or 1000BASE-ZX on a port-by-port basis.The Cisco GLC-ZX-SM operates on ordinary single mode fiber optic link spans of up to 70 km in length. Link spans of up to 100 km are possible using premium single mode fiber or dispersion shifted single mode fiber (premium single mode fiber has a lower attenuation per unit length than ordinary single mode fiber; dispersion shifted single mode fiber has both lower attenuation per unit length, and less dispersion).