Fiber Ports on Cisco 2950 24 port switch

5 pts.
Cisco switches
Fiber optic networking
Fiber Ports
I have fiber connected to my 2950 but it does not work. I did a light test with the fiber strands and they are good. Is there anything else tyhat I am missing that must be done.

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Do a NO SHUT on the interface. What does it tell you for the ports when you do a SHOW IP INTERFACE BRIEF?

Aside from the above suggestions keep in mind that often I have to invert the fiber pair at one end of the connection making it a cross-over to allow the connection to work. I take it apart and swap the positions at one end to do this.

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  • BlankReg
    The interface should already be no shut, on a switch that is the default. You also need to confirm that the speed is the same at each end. Unlike copper RJ45 connections, fibre only operates at one speed, either 100Mbps or 1000Mbps. You can not mix 100BaseF and Gigabit. I know for most that is basic, but I have actually been called out to diagnose exactly this issue - so it does happen. What you may like to do is move one of the switches to the same location as the other, and try them connected together with a short fibre patch lead. If that works, then you know that all the hardware is good. If it still will not work on the main fibre link, then that has the problem. It maybe that it worked OK at 100Mbps, but not at 1000Bps, as the fibre is not (or no longer) capable of the higher speed. That means a replacement of the fibre. Also try a different pair of fibres, if there are some spare, and try every combination of the spare fibres you have, one of them may work.
    12,325 pointsBadges:
  • Snapper70
    Are you sure it's default configuration at both ends? If you have VLAN mismatches or forced trunking at one end, you may not get connectivity. Of course, you also didn't indicate how far it IS working. Do you get a link light at all? If not, could be a speed or crossed fiber issue. At both ends, do a "show interface status" and check - do the optics types match as reported? Once you have basic physical connectivity, the same display can indicate status; plus the "show log" (or even serially hooked up to the console) will indicate changes in link and connectivity status.
    920 pointsBadges:

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