ONTAP FC port shows low receive power (RX) value

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Category:: fabric-interconnect-and-management-switches

Specialty:: san

Last Updated:

Applies to

ONTAP
FCP
Brocade SAN switch
Cisco SAN switch

Issue

FC port shows low RX value on ONTAP as per fcp adapter show output:

::> fcp adapter show -instance -node nodename -adapter 0a
[...]
        Received Optical Power: 241.3 (uWatts)
    Is Received Power In Range: false
 SFP Transmitted Optical Power: 600.4 (uWatts)
        Is Xmit Power In Range: true
                    DDM Status: 30
              Is Xmit Disabled: false
               Is Xmit In Fault: false
            Is Receiver In LOS: false

FCP-Adapter.xml log on ONTAP reports low Rx power , indicating issue upstream to Ontap:

Below risk is reported in AIQM-
- RISK: SFP receive power of the SFP connected to netapp port 9c is below the recommended value.

• The sfp looks good on both ends. Tx and Rx both are within the recommended range on both ends.

In EMS logs we observed link break detected and link up errors along with AEN errors:

Wed Apr 12 03:42:08 +0200 [nxx-0x: fct_tpd_work_thread_0: scsitarget.slifct.linkBreak:error]: Link break detected on Fibre Channel target HBA 2c with event status 1 , topology type 1, status1 0x0, status2 0x0.

Wed Apr 12 03:42:09 +0200 [nxx-0x: fct_tpd_work_thread_0: scsitarget.hwpfct.linkUp:notice]: Link up on Fibre Channel target adapter 2c.

fcp.io.status:debug]: STIO Adapter:0e AEN 0x8048 (RECV_ERROR) MboxStatus1 0x1002 MboxStatus2 0xa1

From sfpshow logs from Brocade switch:

RX Power: -1.9 dBm (647.5uW) TX Power: -4.6 dBm (349.3 uW)

`show interface brief`logs on Cisco switch connected to affected NetApp port reports switch port status as "errDisabled"

----------------------------------------------------------------------------------------- Interface Vsan Admin Admin Status SFP Oper Oper Port Logical Mode Trunk Mode Speed Channel Type Mode (Gbps) ----------------------------------------------------------------------------------------- fc1/27 3 auto off errDisabled swl -- -- -- --

show int transceiver detail output on Cisco switch reports low Tx power, indicating issues on the switch end sfp:

SFP Diagnostics Information: ---------------------------------------------------------------------------- Alarms Warnings High Low High Low ---------------------------------------------------------------------------- Temperature 40.16 C 75.00 C -5.00 C 70.00 C 0.00 C Voltage 3.33 V 3.63 V 2.97 V 3.46 V 3.13 V Current 0.00 mA 12.00 mA 4.00 mA 11.20 mA 4.80 mA Tx Power -40.00 dBm 5.00 dBm -12.20 dBm 2.00 dBm -8.20 dBm Rx Power -0.49 dBm 5.00 dBm -15.20 dBm 2.00 dBm -11.20 dBm Transmit Fault Count = 0 ---------------------------------------------------------------------------- Note: ++ high-alarm; + high-warning; -- low-alarm; - low-warning

The Rx and Tx values for the port on the Cisco switch are displaying as optimal, and the port status is up.

fc2/42 is up [... ....] Temperature 38.33 C, Voltage 3.38 V, Current 6.54 mA, TxPower -6.08 dBm, RxPower -3.11 dBm

The port on the switch end has been toggled, yet the Rx power on the FC port at the NetApp end remains low.

Tue May 28 23:35:39 2024:type=update:id=10.0.xx.xyz@pts/0:user=admin:cmd=configure terminal ; interface fc2/42 (SUCCESS) Tue May 28 23:35:57 2024:type=update:id=10.0.xx.xyz@pts/0:user=admin:cmd=Interface fc2/42 state updated to down Tue May 28 23:35:57 2024:type=update:id=10.0.xx.xyz@pts/0:user=admin:cmd=configure terminal ; interface fc2/42 ; shutdown (SUCCESS) Tue May 28 23:41:05 2024:type=update:id=10.0.xx.xyz@pts/0:user=admin:cmd=Interface fc2/42 state updated to up Tue May 28 23:41:05 2024:type=update:id=10.0.xx.xyz@pts/0:user=admin:cmd=configure terminal ; interface fc2/42 ; no shutdown (SUCCESS)

Low throughput on adapter in System Manager
As part of troubleshooting below steps can be performed:
- Low RX on ONTAP usually indicates a hardware fault on the transmitting end (either switch/ patch panels)
- Perform cable testing along with patch panel to check if cable is healthy
- Swap the cable to a different open working port on switch end to see if the problem follows
- Clean the connection on the cable and on both SFPs