GLC-SX-MMD/ OM3 Cable / Cisco WS-C2960X-S4PS-L

[Kathirsiva]

Switch--2--switch connection. (same switch at both end)

Both ends configured with the below configuration.

# int gi1/0/25

#switchport mode trunk

#switchport nonegotiate

but still, the fibre link not detected, even tried with the different configuration.

SFP module product name : 6COM (6C-SFP-0301D)

Should I want to change anything? Please, assist on this.

Thanks.

[Seb Rupik]

Hi there,

Cisco switches are very particular about the optics you use on them, I suspect your 6com SFP is not being detected.

What is the output of:

sh inv

sh int gi1/0/25 trans det

You will probably have great sucess if you use Cisco branded SFPs:

https://www.cisco.com/c/en/us/td/docs/interfaces_modules/transceiver_modules/compatibility/matrix/GE_Tx_Matrix.html#_Toc520401113

cheers,

Seb.

[Kathirsiva]

Hi Seb,

Thanks for your kindly help....

this is the output...

BR-SWT-02#sh inv
NAME: "1", DESCR: "WS-C2960X-24PS-L"
PID: WS-C2960X-24PS-L , VID: V05 , SN: FOC22****

NAME: "GigabitEthernet1/0/25", DESCR: "1000BaseSX SFP"
PID: GLC-SX-MMD , VID: V01 , SN: 6C3*****

BR-SWT-02#sh int gi1/0/25 trans det

ITU Channel not available (Wavelength not available),
Transceiver is internally calibrated.
mA: milliamperes, dBm: decibels (milliwatts), NA or N/A: not applicable.
++ : high alarm, + : high warning, - : low warning, -- : low alarm.
A2D readouts (if they differ), are reported in parentheses.
The threshold values are calibrated.

High Alarm High Warn Low Warn Low Alarm
Temperature Threshold Threshold Threshold Threshold
Port (Celsius) (Celsius) (Celsius) (Celsius) (Celsius)
--------- ------------------ ---------- --------- --------- ---------
Gi1/0/25 13.1 90.0 85.0 -40.0 -45.0

High Alarm High Warn Low Warn Low Alarm
Voltage Threshold Threshold Threshold Threshold
Port (Volts) (Volts) (Volts) (Volts) (Volts)
--------- --------------- ---------- --------- --------- ---------
Gi1/0/25 3.32 3.80 3.70 2.80 2.70

Optical High Alarm High Warn Low Warn Low Alarm
Transmit Power Threshold Threshold Threshold Threshold
Port (dBm) (dBm) (dBm) (dBm) (dBm)
--------- ----------------- ---------- --------- --------- ---------
Gi1/0/25 -6.7 -1.0 -2.0 -10.0 -11.0

Optical High Alarm High Warn Low Warn Low Alarm
Receive Power Threshold Threshold Threshold Threshold
Port (dBm) (dBm) (dBm) (dBm) (dBm)
------- ----------------- ---------- --------- --------- ---------
Gi1/0/25 -40.0 -1.0 -2.0 -19.0 -20.0

[Seb Rupik]

OK, so the SFP is being detected.

What is the distance between the two switches?

Have you tried changing the polarity of the fibre cable at one end of the connection, ie chaging which port (Rx/Tx) on the SFP the fibres in the pair are connected to?

cheers,

Seb.

[Kathirsiva]

Hi,

approximately 250 meters between 2 switches.

Not yet tried the polarity change option...Let me try and update here...thanks Seb....

[Kathirsiva]

Hi,

Still, I am experiencing the same issue even after do the polarity change.

I am sure the SFP module detected at both ends, also tried with OM1 and OM3 cables.

Should I want to check with any other SFP module which is compatible? any suggestion? thanks

[Seb Rupik · Accepted solution]

Just to confirm, when you change the polarity of the fibre cable, in either configuration does the link light on the switchport ever become lit green?

If it does, please can you provide the output of:

sh int gi1/0/25 switchport

If the light is never green, then it inidicates a Layer1 issue and you should check the cable.

Regarding the SFP, a genuie Cisco GLC-SX-MMD would be ideal, and both switrches should be running a minimum IOS version of 15.0(2)EX as stated in the compatiability matrix above.

cheers,

Seb.

[Kathirsiva]

finally solved when trying with another SFP module from the different provider.

Thanks for your great support.

[yusuf habibi]

I have same problem, but i solved the issue.
before i put command under interface "switchport nonegotiate"
fiber link not coming up, then i remove the command line "switchport nonegotiate"

I hope this help:)