a network cable is unplugged

[Stuart Teo]

Hi Hao Tian,

With the network cable unplugged, are you able to do an "IPCONFIG" from a command prompt? If you're using a newer Windows version, you should be assigned a 168.x.x.x address if you're a DHCP client. Ping 127.0.0.1 and if that works, we can rule out Layer 3 failure.

An "IPCONFIG /ALL" should reveal your MAC address. If that works, it means that the OS+driver thinks that the NIC is working fine. We can almost rule out Layer 2 failure.

Given the intermitent nature of the problem, Layer 1 is the prime suspect. If you're sure that your UTP network cable is good, chances are it's bad RJ45 connector on your laptop may it be (a) the RJ45 connector being bad itself or (b) a cold solder between the connector pins and the PCB.

[Mart_7]

sorry to all... think it's nothing of all..

Since XP I knew this problem on several networks...

I would have a look at the error statistic on the Switchport you are connected...

It can be cuased with by a saturated network (not only the local - even in direction to your servers)

It can be caused by Duplex/Full/Half-Settings when the switchport is not properlly set (e.G Cisco Portfast)...

looking forward for further feedbacks...