Help, a Network Interface Card problem

[dannyt]

Hi

I wonder if anybody could shed some light on a problem I am having.

I have an inherited, a test station that I am reliably ensured used to work OK.

In my test setup I have two NIC’s in a PC used to control two UUT's. The Ethernet cables from each NIC goes to a separate non-configurable NetGear Router GS605 , from each router one cable runs to a UUT and another to a Bit Error Rate Tester.

During normal testing I need to talk to and configure the UUT. At a particular point in the test I setup a loop to the BERT tester and try to measure the Bit Error Rate. Obviously and traffic from the PC’s cards will be seem by the BERT Tester as error bit so I need to ensure there is non. This has in the past be achieved by set the NIC state to disabled. Before the test station was shipped over to me this disabling of the card, worked.

However I am now finding that when I disable the NIC’s the LED on the appropriate router port does not go out but switchs from green to yellow (amber) and when I start up the traffic in the BERT tester the LED flashes and I see errors

.

I should add I have the same test software, the same hardware but that Windows 7 has been re-installed on my test machine since it last worked. To get the test to work now I need to physically take the Ethernet cables out of the PC.

Does anybody have any ideas or suggestions, I do wonder what is the difference is between physically disconnecting a cable from a NIC and disabling it.

cheers

Dannyt

[Phillip Brooks]

When the LED color changes, this usually indicates a change in line speed (Gb/100Mb/10Mb). How exactly are you disabling the NIC?

I was just playing around this weekend with my NAS at home and had to 'default' the router it was connected to. My netbook PC was recently rebuilt with Win7 and I saw that there is an IPv4 and an IPv6 stack running on the Ethernet port.

I kept seeing a strange IP address being assigned by my router to the netbook, and after I disabled Win7 IPv6 and rebooted, the netbook borrowed an address from the router that I expected. If you are just disabling IP (v4?) you might still have another protocol using the NIC.

If this is for testing only, I would disable any protocol you don't need.

Edited October 17, 2011 by Phillip Brooks

[dannyt]

When the LED color changes, this usually indicates a change in line speed (Gb/100Mb/10Mb). How exactly are you disabling the NIC?

I am using the devcon command line utility to programmatically disable the NIC from within LabVIEW, I have confirmed the NIC is disabled by using Wireshark, a BroadCom utility software package and IPConfig /all

I was just playing around this weekend with my NAS at home and had to 'default' the router it was connected to. My netbook PC was recently rebuilt with Win7 and I saw that there is an IPv4 and an IPv6 stack running on the Ethernet port.

I kept seeing a strange IP address being assigned by my router to the netbook, and after I disabled Win7 IPv6 and rebooted, the netbook borrowed an address from the router that I expected. If you are just disabling IP (v4?) you might still have another protocol using the NIC.

I have diabled IPv6, QOS in fact everthing but IPv4, my IP addresses are all static and manually set. I noticed I said in my original mail I was connect to a "router" it should really say a "switch"

Maybe I will try and disable manually just to see what happens.

cheers

Danny

[asbo]

Yeah, disable manually and see if it gives you the correct behavior. It's a shot in the dark, but maybe you could try using devcon to change you IP address to a different subnet, so even if it does try to keep talking it'll be on a different subnet - unless your BERT picks that up too ...

In a past project, we weren't doing any error testing, but we did have to remove the UUT from the network briefly. We used managed switches and SNMP to pull that off though - maybe it'd be worth upgrading in your case?

[dannyt]

Hi Phillip & Asbo

Guys thanks for your suggestion, I have finally got to the bottom of this problem. I was focusing on the wrong area as happens at times. What I was unaware of was that the settings on the BERF Tester itself had also been played with.

Though I did look at the testers setting I missed something and as all seemed to work OK when I disconected the NIC I foolishly focused on them.

I turned out that the BERT TX profile had an invalid destination MAC address in it, I still do not really understand how with the NIC's disconnect I did not still get errors but setting the MAC address correct has fix my problem. I now need to read up more on unmanaged switches and Layer 2 testing.

thanks again

Dannyt