The Cisco GLC-BX40-D-I- GLC-BX40-DA-I- and GLC-BX40-U-I SFPs operate on a single strand of standard SMF.

A GLC-BX40-D-I or GLC-BX40-DA-I device connects to a GLC-BX40-U-I device with a single strand of standard SMF with an operating transmission range up to 40 km.

The communication over a single strand of fiber is achieved by separating the transmission wavelength of the two devices. The GLC-BX40-D-I- GLC-BX40-DA-I- and GLC-BX40-U-I SFPs also support Digital Optical Monitoring (DOM) functions according to the industry-standard SFF-8472 Multisource Agreement (MSA). This feature gives the end user the ability to monitor real-time parameters of the SFP- such as optical output power- optical input power- temperature- laser bias current- and transceiver supply voltage.