3Com 3CBLSF26PWRH User Manual page 115

All ports appear to show continual activity.
There may be broadcast storms on the network. Remove port connections one at a time, waiting a few
seconds between each port. If the LEDs go off after removing a port connection, the device that was
connected to that port is introducing an excessive amount of broadcast frames to the network. Some
pieces of network equipment operate by sending out broadcast frames regularly.
Refer to the documentation that accompanies the switch for information on disabling the broadcast
operation.
If the problem persists and the unit still does not operate successfully, contact your 3Com network
supplier with the following information before returning the unit:
Product number and serial number (printed on a label supplied with the unit).
A brief description of the issue.
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