Does this mean a bad SFP+ module?

[m1xed0s]

I have brand new 9504 with two 48Port line cards and NX-OS 7.0(3)I4(6). I have port 1/47 connected with 10Gbps SFP+ but I got warning messages periodically.

%ETHPORT-4-IF_SFP_WARNING: Interface Ethernet1/47, High Rx Power Warning

I did check the SFP+ module. Does it look abnormal to you?

N9K1# show interface eth1/47 transceiver details
Ethernet1/47
    transceiver is present
    type is 10Gbase-ER
    name is CISCO-OCLARO
    part number is TRS7050EN-S103
    revision is 0012
    serial number is ONT204500F3
    nominal bitrate is 10300 MBit/sec
    Link length supported for 9/125um fiber is 40 km
    cisco id is 3
    cisco extended id number is 4
    cisco part number is 10-2531-02
    cisco product id is SFP-10G-ER
    cisco vendor id is V02

           SFP Detail Diagnostics Information (internal calibration)
  ----------------------------------------------------------------------------
                Current              Alarms                  Warnings
                Measurement     High        Low         High          Low
  ----------------------------------------------------------------------------
  Temperature   31.75 C        75.00 C     -5.00 C     70.00 C        0.00 C
  Voltage        3.28 V         3.63 V      2.97 V      3.46 V        3.13 V
  Current       45.34 mA      120.00 mA    20.00 mA   112.00 mA      24.00 mA
  Tx Power      -0.49 dBm       6.99 dBm   -8.72 dBm    3.99 dBm     -4.71 dBm
  Rx Power       0.22 dBm  +    1.99 dBm  -20.00 dBm   -1.00 dBm    -15.85 dBm
  Transmit Fault Count = 0
  ----------------------------------------------------------------------------
  Note: ++  high-alarm; +  high-warning; --  low-alarm; -  low-warning

There are several bugs opened right now regarding that error message on different OS and platforms.CSCul19908, CSCub36105 and CSCuy49815

So is this a cosmetic thing OR bad module/fibre cable/line card? BTW, I do not see the syslog message of warning clear...

[chrihussey]

I don't see a bug here but an actual issue. Your RX power is .22 dBm and the high warning threshold is -1 dBm. So the RX light level is too high and you could damage the receiver.

Doubtful it is a bad fiber, as that would probably result in a low light level and not a high one. You could swap the SFP to see it the other sees different light levels.

Other than that, suggest using an optical attenuator on the RX of that SFP.

Possibly a 3 - 5dB one should bring you within range.

Hope this helps

[m1xed0s]

I swapped cable on 47 and now I do not have the messages anymore after reboot...But the measurement still shows value above the -1dBm (something like -0.03dBm).

Do you have a known good part# for the attenuator? I never used one before on Fibre...

Also if we change the optic to a 1Gbps one and all the reading are healthy...So firmware issue with the 10Gbps SFP+?

N9K1-CORE-GOB# sh inter eth1/47 transceiver details
Ethernet1/47
    transceiver is present
    type is 1000base-LH
    name is CISCO
    part number is SFCT-5716PZ-CS1
    revision is 002
    serial number is AVJ204336SG
    nominal bitrate is 1300 MBit/sec
    Link length supported for 9/125um fiber is 10 km
    cisco id is 3
    cisco extended id number is 4
    cisco part number is 10-2625-01
    cisco product id is GLC-LH-SMD
    cisco vendor id is V01

           SFP Detail Diagnostics Information (internal calibration)
  ----------------------------------------------------------------------------
                Current              Alarms                  Warnings
                Measurement     High        Low         High          Low
  ----------------------------------------------------------------------------
  Temperature   29.75 C        90.00 C    -10.00 C     85.00 C       -5.00 C
  Voltage        3.32 V         3.63 V      2.97 V      3.47 V        3.14 V
  Current       14.63 mA       65.09 mA     2.40 mA    61.00 mA       3.00 mA
  Tx Power      -7.23 dBm       0.00 dBm  -13.01 dBm   -3.00 dBm     -9.50 dBm
  Rx Power      -7.74 dBm       0.00 dBm  -23.01 dBm   -3.00 dBm    -19.20 dBm
  Transmit Fault Count = 0
  ----------------------------------------------------------------------------
  Note: ++  high-alarm; +  high-warning; --  low-alarm; -  low-warning

[chrihussey]

Changing the SFP to the GLC-LH-SMD (I assume on both sides) really is not comparable. It is a lower powered laser which does not have the distance the SFP-10G-ER. So by default your RX would be lower.

What is the distance of to fiber run? If less than 10km then a SFP-10G-LR would be best and you shouldn't need attenuation.

Sorry, I have one or two fiber attenuators on my network but am unfamiliar whee they came from. They are a fairly simple device so you should be OK with any reputable supplier. I took a quick look and found this:

http://fiber-attenuators.com/lc_singlemode_fiber_optic_attenuator.htm

Regards

[m1xed0s]

The distance will be more than 10KM and GLC-LH-SMD is just for a quick testing as they were handy available. The ones will be going into production are 1Gbps modules supporting 26KM distance.

I will check the link but if attenuator is required for long range fibre, why no Cisco documents shows so?

[chrihussey · Accepted solution]

Just did some checking, they actually do and provide a part number (15216 ATT LC 5=).

Here's the document link:

https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/transceiver-modules/data_sheet_c78-455693.html?dtid=osscdc000283

[m1xed0s]

Okey, thanks alot. Obviously I did not pay attention to the "****" parts...