100Base FX and 1000Base LX - are they compatible?

I have connected a D-Link DMC-515SC media converter with a 100Base FX port to a Cisco switch with a 1000Base LX port via a single mode patch lead but having issues. Tried swapping cores but not successful. Are they compatible?

Solution 1:

100Base FX and 1000Base LX - are they compatible?

No, not normally.

While both use 1300 nm light, 100BASE-FX is designed for multi-mode fiber and 1000BASE-LX for single-mode. Depending on the exact transceiver types, one of the fiber types might work - if SMF doesn't, try MMF (reach may be rather poor). Also, the SFP transceiver needs to be flagged as 100M compatible (few are), and the SFP port may require explicit configuration to 100M (interface x speed 100). After all, you might need a 100BASE-FX SFP module for the switch, or a Gigabit media converter.