Hi,
Alex, we solved the issue as soon as we've used genuine or 100% compatible SFPs.
I'm talking about 100M-LX, but it's doesn't make any difference I'sure. The switch running Junos 15.1R5.5, but previous SFPs we tried did not work properly under various of Junios versions we've tried: 11/13/14/15.
So the issue was incompatible SFPs and not the switch or Junos themselves.
See attached screenshot for details.
Hope it helps.
