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User cannot get a link up with a GBIC port

Core issue

Gigabit Ethernet is an extension of the Ethernet protocol, but increases speed tenfold over Fast Ethernet to 1,000 Mbps or 1 Gbps. Failure to get Gigabit Interface Converter (GBIC) up during installation could be as a result of system requirements not met, incorrect cable installed, lack of power to the device, configuration errors or hardware failure.


If the gigbit link does not come up, perform these steps:

  1. Verify that system requirements are met for GBIC installation by referring to System Requirements to Implement Gigabit Ethernet on Catalyst Switches.  

  2. If the switch is not recognizing a GBIC module, make sure the switch is running at least the minimum Catalyst OS (CatOS) or Cisco IOS  Software. For more information, refer to the Software Advisor.  

  3. Ensure that the device has power. This includes having enough available power for all hardware installed in the chassis, particularly for the Catalyst 4000 or 6000 series. For more information, refer to Power Management for Catalyst 6000 Series Switches.  

  4. Verify that the GBIC cable is connected to another active network device and that the port is not shut down.  

  5. Replace cable with a known good cable.  

  6. Make sure GBICs are matched on either side of the connection.  

    Note: For gigabit connections, GBICs need to be matched on each side of the connection. There are different types of GBICs, depending on the cable and distances involved: short wavelength (SX), long-wavelength/long-haul (LX/LH) and extended distance (ZX). An SX GBIC needs to connect with an SX GBIC; an SX GBIC does not link with an LX GBIC. Also, some gigabit connections require conditioning cables, depending on the lengths involved.

  7. Make sure the flow control and port negotiation settings are consistent on both sides of the link.    

    There may be incompatibilities in the implementation of these features if the switches being connected are from different vendors. If in doubt, turn these features off on both switches.

  8. Swap GBIC to a different slot. Also, try using a spare GBIC to see if it works. 

If the issue is not resolved, please contact Cisco Technical Support online using the TAC Service Request Tool.