Catalyst GigaStack GBIC
Downloads: This chapterpdf (PDF - 110.0 KB) The complete bookPDF (PDF - 952.0 KB) | Feedback


Table Of Contents



Table 3-1 describes how to identify problems with the switch and GigaStack GBIC and how to resolve them.

Table 3-1 Common Problems and Their Solutions 

Possible Causes
Corrective Action

GBIC module slot LED is amber.

Spanning Tree Protocol (STP) is checking for loops.

Wait for STP to complete its search. The LED turns green when STP completes its check.

Port is initializing, it was disabled by management or an address violation, or it was blocked by STP.

Use the Cluster Management Suite or the IOS command-line interface to check the status of the port and to enable it.

GBIC module slot LED is flashing green and amber.

Port is experiencing error frames. This could be due to a duplex mismatch caused by autonegotiation, collisions, cyclic redundancy check (CRC) errors, or alignment errors.

Remove and reinsert the GigaStack GBIC.

GBIC module slot LED is off.

Device has no power.

Ensure that the switch and the target device have power.


No link or port was shut down administratively.

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


Bad cable.

Replace with a known good cable.

GigaStack GBIC LED blinks any color for more than 1 minute.

Link flap (the link keeps going up and down).

Remove and reinsert the GigaStack GBIC.

Upgrade all the switches in a series to the same software version; otherwise, the loop-breaking algorithm might never resolve itself. For example, if the stack includes only Catalyst 2900 series XL and 3500 series XL switches, they must run Release 12.0(5)XU or later. If the stack includes a mixture of Catalyst 2900 series XL, 3500 series XL, 2950, and 3550 switches, all the 2900 XL and 3500 XL switches must run Release 12.0(5)XW or later, all Catalyst 2950 switches must run Release 12.1(6)EA2 or later, and all Catalyst 3550 switches must run Release 12.1(4)EA1 or later.

If no loop exists in the GigaStack GBIC stack, you can disable the loop-breaking algorithm by using the no gigastack loop-breaking [interface-id] global configuration command.

GigaStack GBIC LED color is incorrect (for example, the GBIC is not connected to another device, but the LED is green).

The GigaStack GBIC is in an indeterminate state.

Remove and reinsert the GigaStack GBIC.