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Refer to the information about LEDs given earlier in this guide to
see if the problem can be identified and rectified. Here are some
common problems that can occur:
A link is connected but the Link/Activity Status LED for the
port does not light
There is a problem with this connection. Check that:
■ The device being connected to is powered on and operating
correctly.
■ The cable is connected at both ends.
■ The cable is not damaged.
■ If the connection is to a workstation, that the workstation's
network interface is installed and configured correctly.
■ The correct category of cable is being used for the required
link speed. Category 3 cable can be used for 10BASE-T
operation only. Category 5 cable is required for 100BASE-TX
or 1000BASE-T. 3Com recommends Category 5e or 6 cable
for 1000BASE-T operation.
A fiber cable is connected but the Module Active LED does
not light
Check that:
■ The Receive (RX) and Transmit (TX) cable connectors are not
swapped.
■ The fiber cable is in good condition.
■ The SFP module is correctly inserted.
■ A 3Com SFP module is being used. Refer to “Approved SFP
Transceivers” on page 14 for details.
■ The equipment at the far end is installed and correctly
configured.
The Link/Activity LED is lit but the network performance of
the Switch is poor
The Switch supports full-duplex auto-negotiation. If the
connected device does not support auto-negotiation, ensure it is
configured for half-duplex operation only. If the connected device
has auto-negotiation disabled or over-ridden, and is configured
as full duplex, the Switch will configure the link as half duplex,
causing a mis-match that will reduce network performance when
data is transmitting and receiving simultaneously on the same
link.
Ensure that the connected device has either:
■ Auto-negotiation enabled, or
■ The ports are configured for half-duplex operation
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 device for information on disabling the broadcast operation.
PROBLEM SOLVING