Brocade switch port with Low Rx power due to faulty end device sfp

Applies to

Brocade switches

Issue

• PCS errors observed on switch ports:

/fabos/cliexec/porterrshow :
          frames     enc    crc    crc    too    too    bad    enc   disc   link   loss   loss   c3timeout   pcs   uncor
       tx     rx     in    err    g_eof  shrt   long   eof     out   c3    fail    sync   sig    tx    rx     err    err         

172:  276    165      0      3      2      0      0      1      0      0      2      0      2       0    0     89.7m   0

• Low RX power reported: 

=============
Slot  5/Port 28:
=============
RX Power:    -6.9    dBm (203.9uW) ​​​​​​
TX Power:    -1.1    dBm (784.2 uW)

RX Power:    -inf    dBm (0.0  uW)
TX Power:    0.0     dBm (1006.0 uW)

• portstatsshow output reports er_pcs_blk error counter:

er_bad_os               0                  Invalid ordered set
er_pcs_blk              510                 PCS block errors

• SQL alert "Disk Performance Degrade (Event ID 153)" reported on the host

• Performance issues reported on the host and IO WQE error with Ext_Status 0x1d reported for the affected host SID

• Rules -defALL_HOST_PORTSITW_21 , defALL_TARGET_PORTSITW_11 and defALL_32GSWL_SFPRXP_63 triggered under errdump:

2022/10/19-03:45:31, [MAPS-1003], 257687, SLOT 2 | FID 128, WARNING, XXX, slot12 port13, F-Port 12/13, Condition=ALL_HOST_PORTS(ITW/min>21), Current Value:[ITW, 20777 ITWs], RuleName=defALL_HOST_PORTSITW_21, Dashboard Category=Port Health.

2022/10/19-03:45:31, [MAPS-1003], 257687, SLOT 2 | FID 128, WARNING, XXX, slot4 port32, F-Port 4/32, Condition=ALL_TARGET_PORTS(ITW/min>11), Current Value:[ITW, 15348 ITWs], RuleName=defALL_TARGET_PORTSITW_11, Dashboard Category=Port Health.

2022/10/19-03:46:25, [MAPS-1004], 257747, SLOT 2 | FID 128, INFO, XXX, SFP 12/13, Condition=ALL_32GSWL_SFP(RXP<=63), Current Value:[RXP, 44 uW], RuleName=defALL_32GSWL_SFPRXP_63, Dashboard Category=Port Health.

• Check the Rx power on the switch end under sfpshow and ensure that the Rx power is within the recommended range
• Low Rx power indicates and issue upstream to the switch, refer Low Rx power reported on Brocade switch due to faulty end device
• Alternatively, you can plug into a known good device for fault isolation of cable and sfp by following below steps:

1. In order to do fault isolation if the hardware, move the cable to next available port on the switch end and observe for any increments:
2. If the issues follows on new port, replace the cable/patch panel and verify the port counters
3. If the issue does not follow to the new port, then swap the SFP of the affected port with a good known working SFP and see if the errors subsides

• Clear switch stats (statsclear and slotstatsclear), and observe the port (using porterrshow) to further verify if the errors are still getting logged