MikroTik CSS610 to Cisco Nexus 5596: transceivers detected, no link, four bad fibre patch cords

A MikroTik CSS610-8P-2S+ (SwOS Lite) needed to connect its SFP+ ports to a Cisco Nexus 5596UP. The ports showed the transceivers in the web UI but no link, after trying several fibre cables and transceivers. The switch web UI listed vendor and type for each module, yet the port stayed at no-link regardless of which optic or fibre was used, so the poster suspected either a Nexus optic-validation issue or bad cabling.

• Hardware: MikroTik CSS610-8P-2S+, Cisco Nexus 5596UP
• Transceivers: 10G SFP+ (generic and Cisco)
• Form factor: SFP+

Symptoms / messages:

transceiver detected but no link