Brocade switch port offline and in “No light” state with low Rx power due to faulty cable

Applies to

Brocade Switch

Issue

• Switch port state shows as No_light under switchshow output:

Index Port Address Media Speed  State    Proto
==============================================
 ----- Truncated -----
   5   5   010500   id     4G   No_Light    FC  

• porterrshow output shows that link fail, loss sig errors are observed

/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
130:  403    471       0       0      0       0       0      0       0       0    334       0       5.4k   0       0       0      0       0       0

• Portshow of the affected port reports offline status:

portshow 5
portDisableReason: None
portCFlags: 0x0
portFlags: 0x21     PRESENT U_PORT DISABLED
LocalSwcFlags: 0x0
portType:  26.0
portState: 2    Offline  
Protocol: FC
portPhys:  4    No_Light     portScn:   2    Offline   
port generation number:    748
state transition count:    11      

• Fabric logs shows that port being flapped multiple times

Switch 0; Thu Jun  1 19:17:40 2023 IST (GMT+5:30)
19:17:40.873933 SCN Port Offline;rsn=0x2,g=0xf1e           A2,P0  A2,P0  130  NA
19:17:40.873942 *Removing all nodes from port              A2,P0  A2,P0  130  NA
19:22:14.346217 SCN LR_PORT(0);g=0xf1e                     A2,P0  A2,P0  130  NA
19:22:14.396548 SCN Port Online; g=0xf1e,isolated=0        A2,P0  A2,P1  130  NA
19:22:14.396643 Port Elp engaged                           A2,P1  A2,P0  130  NA
19:22:14.396657 *Removing all nodes from port              A2,P0  A2,P0  130  NA
19:22:14.397110 SCN Port F_PORT                            A2,P1  A2,P0  130  NA
19:22:14.444090 SCN Port Offline;rsn=0x2,g=0xf20           A2,P0  A2,P0  130  NA
19:22:14.444095 *Removing all nodes from port              A2,P0  A2,P0  130  NA
19:22:19.256279 SCN LR_PORT(0);g=0xf20                     A2,P0  A2,P0  130  NA
19:22:30.799147 SCN LR_PORT(0);g=0xf20                     A2,P0  A2,P0  130  NA
19:22:30.899258 SCN Port Online; g=0xf20,isolated=0        A2,P0  A2,P1  130  NA
19:22:30.899357 Port Elp engaged                           A2,P1  A2,P0  130  NA
19:22:30.899371 *Removing all nodes from port              A2,P0  A2,P0  130  NA
19:22:30.900041 SCN Port F_PORT                            A2,P1  A2,P0  130  NA    

• sfpshow reports Rx value is too low

Slot  5/Port 21:
=============
Identifier:  3    SFP
Connector:   7    LC
Transceiver: 6804404000000000 8,16,32_Gbps M5 sw Short_dist
[...]
Vendor Name: BROCADE
Vendor OUI:  00:05:1e
Vendor PN:   57-1000333-01
Vendor Rev:  A
[...]
Temperature: 59      Centigrade
Current:     7.640   mAmps
Voltage:     3327.1  mVolts
RX Power:    -25.1   dBm (3.1  uW)
TX Power:    -1.3    dBm (743.9 uW)

• Invalid transmit word(ITW) error observed for the port in errdump logs

2022/11/27-00:23:05, [MAPS-1003], 84606, SLOT 2 | FID 128, WARNING, NTTC_X6_108_FAB2, slot10 port38, F-Port 10/38, Condition=ALL_TARGET_PORTS(ITW/min>11), Current Value:[ITW, 237558518 ITWs], RuleName=defALL_TARGET_PORTSITW_11, Dashboard Category=Port Health.
2022/11/27-00:24:05, [MAPS-1003], 84607, SLOT 2 | FID 128, WARNING, NTTC_X6_108_FAB2, slot10 port38, F-Port 10/38, Condition=ALL_TARGET_PORTS(ITW/min>11), Current Value:[ITW, 222669296 ITWs], RuleName=defALL_TARGET_PORTSITW_11, Dashboard Category=Port Health