[j-nsp] HS link FIFO underflows

[moki]

Hello
I've upgraded MX-480 to version 11.2R5.4
After upgrade i noticed there are error on one of the sonet interface HS
link FIFO underflows: 252
As i understand it indicates hardware errors, but there is also possibility
that there might be software problem - because those error didn't appear
before the upgrade .
I want to make sure that the problem isnt affected because of the software .
Please advice if you know some relevant commands which related to this
issue , or some actions which can be taken to eliminate the software
problem .
If some had same issue what did you do to solve the problem
Here is some output of the FPC
FPC 2            REV 15   750-024387   JW9932            MX FPC Type 2
  CPU            REV 03   710-022351   KF1835            DPC PMB
  PIC 0          REV 08   750-014638   BBAM9654          1x STM-16-4-1 SFP
    Xcvr 0       REV 01   740-011786   718002D00112      SFP-IR
  PIC 1          REV 08   750-014638   XK9253            1x STM-16-4-1 SFP
    Xcvr 0       REV 01   740-011785   PDE1LB7           SFP-SR
The problem is with so-2/0/0 , and its full stm16 ; the second sonet
devided to stm4 slices .

thanks