Laptops retaining IP when cable not connected

[Nick_Parker]

Hi Guys

 

I'm having an annoying problem with a whole bunch of the laptops on our network.

 

They will come to me and tell me that its not connecting to the network,

I'll ipconfig it, and it'll have DHCP IPs assigned to both the WiFi Connection and the Ethernet Connection, even tho the cable is unplugged...

 

If I ipconfig /release and ipconfig /renew the machine, the Ethernet Connection is then assigned a 0.0.0.0 address and the WiFi Connection picks up a new address and everything works.

 

I can't remember now if the icon for the ethernet cable shows that the cable is unplugged or not, but I know it's not a hardware issue, because alot of the notebooks are doing it.

 

Has anybody else experienced anything similar? It's like windows isn't checking the connection and isn't detecting that the connection is lost?

 

Any help or suggestions would be greatly appreciated!

[leco]

I had that issue a while ago. From memory I had to plug the laptop into the network so that the wired network automatically gained an IP address. The wireless card would then kick in and gain an IP as well. I think that the network cable is unplugged message popped up, but am not sure on that.

[Michael]

I can't remember now if the icon for the ethernet cable shows that the cable is unplugged or not, but I know it's not a hardware issue, because alot of the notebooks are doing it.

 

Yes, Windows will display a network icon both for Wireless and Ethernet with a red cross. When an IP is obtained, the Ethernet icon disappears, but the Wireless icon changes and flashes when there's activity. This is the default behaviour, but you can change it in Network Properties.

 

Have you tried updating the driver for both network adapters? Seems odd it "remembers" its IP when a cable is disconnected.

[RabbieBurns]

do they alternate between wired and wireless connections or are they only everc onnected wireless?

 

why not just disable the wired connection?

[Nick_Parker]

I think its the latest drivers, I will make 100% sure tho.

They use both wired and wireless,

when they are working in their classrooms, they use the wired connections (point in every classroom) but when they go into areas like the library, staffrooms etc... then they use wireless...

 

But, they go into an area with wireless, I *THINK* DHCP assigns the wireless an IP address (i'm not sure on the order these things happen, they always come to me after its happened) but the wired card still has an ip address assigned to it and the computer tries to use that instead of the wireless connection.

 

ipconfig /release and ipconfig /renew

 

The wired ip address disappears and the wireless one renews itself and everything is fine, until they go and plug it into their classroom again, then I think it retains an ip for the wireless (even tho they are out of range)...

[Nick_Parker]

I have attached 2 pictures here to show you what I mean,

The first picture "Network_Settings" shows that even tho the lan cable has been unplugged, windows doesn't seem to detect this and still has an ip address assigned to this interface. Even tho the wireless connection is connected and active, nothing on the laptop will connect via the network (I suspect it's still trying to communicate via the lan connection).

 

Picture "Network_Settings2" shows what happens when I do a "Ipconfig /Release"

 

Both interfaces are assigned IP addresses of 0.0.0.0

 

Surely windows should detect that the lan connection is not connected and not assign it any address at all?

 

When doing an "ipconfig /renew", the wireless connection gets a new IP address within seconds and begins communicating, however the process seems to freeze for 30 seconds, I'm guessing it's *trying* to get an IP address via DHCP for the Lan connection even tho it's not connected.

 

Anyways, any suggestions would be appreciated

[kmount]

Weird ... sorry no help here just wanted to post at how odd that is

[PiqueABoo]

The fundamental problem is that XP should be saying "Media disconnected" when the cable isn't there. I'd probably blame the driver, but the first thing to check is that you do NOT have this in the registry:

 

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters

DWORD: DisableDHCPMediaSense 1

[Nick_Parker]

Thanks PiqueABoo,

 

I'll have a look and see, the odd thing is, there are ALOT of laptops doing it and they're all using the latest drivers.