Link light on ethernet card keeps flashing on and off. The connection connects for a second then disconnects

Question

With each flash of the link light the network connects, when the light goes off again, XP says network cable unplugged. The device manager has since stopped refreshing. However the network keeps connecting and disconnecting.

The link light flashes in the same way when the pc is off. I have tried different ports on the switch, the link light on the switch flashes in the same manner. The network cable plugged into a different computer doesnt flash and works fine. I have also put a new network card in the pc which flashes in the same manner.

There is onboard lan and a PCI card, both flash the link light and connect and disconnect in the same way.

Solution

If the activity indicator is flashing very fast or it's on solid then move the cable on the hub/switch to a different port. If the activity light goes out then you have a bad port on the hub/switch. If the symptoms don't change then reload the NIC drivers / replace the NIC. Sometimes a network interface will go bad and just start sending out random data onto the network (called "chattering"). Another symptom of a chattering NIC is almost constant collisions if you are using a hub to connect your PCs. A collision occurs when two or more devices transmit on a shared Ethernet line at the same time.

If you still cannot connect to the network then reload the NIC drivers and protocols, or replace the NIC.

You can also follow these instructions on using Sniffer Pro to try and troubleshoot the issue if it is a chattering NIC.

Comments

[M'vy]

What is the real problem? no connection? or the fact it's flashing?

[Dreendle]

Adding better info.

[FJ de Brienne]

What is at the other end of the network cable?

[Dreendle]

A 16 port switch, however I am now running a new cable.