On UCS C250, after upgrading BIOS version from 1.1 to 1.2 or later, one or both onboard NICs might be down.The reason is that onboard NIC in BIOS setting becomes disabled.
To resolve this issue, please enable the onboard NIC via BIOS setting.
If BIOS version has already been 1.2 or later, this problem won't occur.Only C250 is affected by this issue.
This problem has been filed as CSCti71226 and reported in a release note:http://www.cisco.com/en/US/partner/docs/unified_computing/ucs/release/notes/OL-23492.html#wp89969
If this problem is fixed, it wouldn't occur when upgrading BIOS from 1.1 to the fixed version.But it would occur when upgrading BIOS from 1.2 to the fixed version.So, it decided not to fix CSCti71226.
Nice Catch. I just upgrade a couple C250's yesterday and didn't even notice my LOMs disabling! (Using 10G adapters). Thanks for posting.