3com 2848-sfp plus User Guide
46
T
ROUBLESHOOTING
A link is connected but the Link/Activity Status LED
for the port does not light
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.
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.
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.
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 Present
LED does not light
LED does not light
Check that:
■
The Receive (RX) and Transmit (TX) cable connectors
are not swapped.
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 17 for details.
“Approved SFP Transceivers” on page 17 for details.
■
The equipment at the far end is installed and
correctly configured.
correctly configured.
The Link/Activity LED is lit but the network
performance of the Switch is poor
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.
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.
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.