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-LX/LH on a port-by-port basis.

Mode-conditioning patch cord is required. Using an ordinary patch cord with MMF, 1000BASE-LX/LH SFPs, and a short link distance (10s of meters) can cause transceiver saturation resulting in an elevated bit error rate (BER). In addition, when using the LX/LH SFP with 62.5-micron diameter MMF, you must install a mode-conditioning patch cord between the SFP and the MMF cable on both the transmit and receive ends of the link.

The GLC-LH-SM is a long haul or long wavelength SFP module (1310 nm nominal), for use in 1000BASE-LX links. Use only the SFP modules with your Modular Fast Ethernet line card. Each SFP module contains an internal serial EEPROM that is security-programmed by the SFP manufacturer with information that provides a way for Cisco (through the Cisco IOS software) to identify and validate the SFP module as a module type that was tested and qualified by Cisco to operate properly with Cisco Modular Fast Ethernet line cards.