GLCZXSMRGDST Compatible LC Single Mode Transceiver Module, Full Duplex. The GLCEXSMDST is a Cisco GLC-EX-SMD compatible fiber transceiver module that has been designed, programmed and tested to work with Cisco brand switches and routers. It delivers dependable 1 GbE connectivity over fiber cable, for 1000BASE-EX compliant networks, with a maximum distance of up to 40 km (24.8 mi).