CSS610-8G-2S+IN shows link on SFP+ ports but Intel X520 NICs never see it; SwOS 2.13rc12 works, later builds do not
A MikroTik CSS610-8G-2S+IN showed an active SFP+ link, but Intel X520-DA1/DA2 NICs (Windows, Linux, ESXi) reported no link, reproducibly across multiple transceiver pairs, DACs and two cards. Firmware 2.12, 2.13rc6, 2.13rc12, 2.13rc25 and the final 2.13 were tested. Hardware involved: MikroTik CSS610-8G-2S+IN, Intel X520-DA1, Intel X520-DA2, various SFP+ optics, SFP+ DAC, Intel-branded SFP+.
- Hardware: MikroTik CSS610-8G-2S+IN, Intel X520-DA1, Intel X520-DA2
- Transceivers: various SFP+ optics, SFP+ DAC, Intel-branded SFP+
- Form factor: SFP+, DAC
Symptoms / messages:
switch shows link, NIC shows no link
regression between firmware builds
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Comments 2
Firmware 2.13rc12 gave a stable link for several users, but rc25 and the final 2.13 reintroduced the failure; MikroTik acknowledged the bug with no ETA, so users downgraded to rc12. One user reported success on final 2.13 with Intel-branded transceivers.
Unlocking the X520 EEPROM for non-Intel optics was mentioned but did not address the switch firmware bug.