Insert the module in the correct direction using the alignment guide – improper insertion may damage the port. Remove the protective dust cap from the optical connector. QSFP to QSFP 40G SR4 optical cabling When facing an SR4 QSFP or an MTP cable with their key up, those will always receive on their left (your right if you face them). Note : (silly mnemotechnic) it's a bit like boxing punch and. Small Form-factor Pluggable modules (SFP module) are the workhorses of modern network connectivity, enabling flexible fiber optic or copper links between switches, routers, firewalls, and servers. Figure 1 SFP Optical Module Installation. An optical module is not completely installed in position. Fiber optics support many of today's data center, broadcast, AV.