C3 Tx discards and Frame timeout due to weak RX on Brocade switch

Applies to

Brocade Fabric OS 

Issue

• errdump -a logs frame timeout, stating which port received a frame (rx) and where it cannot be transmitted on (tx)

2022/02/09-22:31:04, [AN-1014], 2266, SLOT 2 | FID 128, INFO, NFAB1, Frame timeout detected, tx port 9/7 rx port 9/27, sid c8f907, did 678740, timestamp 2022-02-09 22:31:04 .

• porterrshow shows related error counter incrementing

/fabos/cliexec/porterrshow:
          frames        enc     crc     crc     too     too     bad     enc    disc    link    loss    loss    frjt    fbsy     c3timeout     pcs      uncor
        tx       rx      in     err     g_eof   shrt    long    eof     out    c3      fail    sync    sig                      tx      rx      err     err
391:   45.3g    3.4g    0       0       0       0       0       0       0      43.1k    5       0       5       0       0      43.1k    0       0       2.5k

• sfpshow indicates low receive power

=============
Port  391:
=============
RX Power:    -8.1    dBm (155.8uW)
TX Power:    -3.0    dBm (500.6 uW)

• portshow indicates the remote device has resetted the link more than the local port sent OFFLINE primitives out

portshow 391
[...]
Lr_in:             133     Ols_in:       5
Lr_out:            7       Ols_out:      6