PROBLEM: Cisco Switch 3750 is not accepting SFP

Unanswered Question
Oct 2nd, 2010
User Badges:

We have the following constellation: We have a switch cluster with three  Cisco 3750G-12TS installed in one ring. After 1 year and a few months  we added an uplink to a new Cisco 3750G-48TS switch via a 100Base-SX SFP, but the uplinks  didn´t worked. There is no light going out of the plugged-in SFPs from  type 1000Base-SX, original Cisco type. Looking on the switch the command  shows, that the SFP is not recognized (= "not present")
Plug-in, Plug-out and so on didn´t helped. We tried also other ports. We removed on SFP from one port, where the switch accepted the SFP as "1000BaseSX SFP", the port status is not updated (= command "show interface status"). Now, the switches are working  in a productive surrounding and there is sensible data running. It  looks like that the Cisco switch 3750 is frozen (= port status). I have seen that  behavior last time, when I wanted to change the switchport settings from  speed 100 and duplex full to auto / auto. The switch didn´t recognized  the change.

(IOS = c3750-advipservicesk9-mz.122-46.SE)

We were not able to bring up one link, because the switch didn´t  recognized the SFP.

We will see. Perhaps a "REBOOT" is necessary. Is there a bug...?

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (2 ratings)
Reza Sharifi Sat, 10/02/2010 - 13:22
User Badges:
  • Super Bronze, 10000 points or more
  • Cisco Designated VIP,

    2017 LAN

Did you get the SFPs from Cisco or a 3rd party vender approved by Cisco?  Sometimes, Cisco devices do not like optics from certain venders.

I know that Transition Networks SFPs work really well with Cisco devices.

richi3161 Sat, 10/02/2010 - 17:57
User Badges:


the SFP modules are approved and original from cisco. They are working in all cases.

It is really a problem with the switch.


From the beginning there were SFPs plugged-in. These I have removed, after they haven´t been used. Now, when a is done, they are still shown!!!

For evidence:

Gi1/0/7                      disabled     1            auto   auto 1000BaseSX SFP <<<- SFP IS UNPLUGGED, BUT STILL SHOWN
Gi1/0/8                      disabled     1            auto   auto 1000BaseSX SFP
Gi1/0/9                      disabled     1            auto   auto Not Present
Gi1/0/10 xxx              disabled     1            auto   auto Not Present <<<- SFP IS PLUGGED IN (from gi1/0/7 or new one, but NOT SHOWN)

I will reboot the switch cluster, NOW!!!

richi3161 Sat, 10/02/2010 - 18:34
User Badges:

Blame on me...

Wrong side of data center. Now it is clear. It is not a technical problem. It is a problem of the human being.

Configuring from outside or remotely is dangerous!



This Discussion

Related Content