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PCS error reported on Brocade switch port with Low Rx power due to faulty cable or sfp

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Category:
fabric-interconnect-and-management-switches
Specialty:
brocade
Last Updated:

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)
 

  • portstatsshow outout reports er_pcs_blk error counter as shown below:
portstatsshow 135
er_bad_os               0                  Invalid ordered set
er_pcs_blk              510                 PCS block errors

  • Rules -defALL_HOST_PORTSITW_21 OR 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.
2022/10/19-03:46:25, [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.
 

 

  • 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.

 

 

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