Hyper-V 2008 core server lost connection with NICs

ricosuave
ricosuave used Ask the Experts™
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I had hardware problems with one of our servers, therefore the main board (with on board NIC's) was replaced. The Hyper-V core server is still starting without any problems, including the virtual machines but I can't communicate anymore with the outside world. When I request the IP settings with IPCONFIG /ALL on the core installation I notice that the MAC address is still the MAC address of the old adapters.

After the initial installation one NIC was visible, so we could connect an IP address and start the configuration manager on another machine. This all worked fine. In the current situation (with the new main board) I can also see all four NIC's in the configuration script SCONFIG. The problem is however that these are not attached anymore to a physical NIC because the main board has been changed.

We don’t use teaming on the core server level, we do however on the virtual server level.

How can I change the MAC addresses to the new ones? Or do I need to re-install?

Thanks,
Erik
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Naga Bhanu Kiran KotaCloud Architecture Manager

Commented:
hi rico,

you dont need to reinstall..shutdown all the vms and remove delete the virtual adapter(external) and also remove all the NICs on the physical machine and reboot the machine.

Then follow this guide in setting up your NICs on the server

http://blogs.msdn.com/b/virtual_pc_guy/archive/2008/01/08/understanding-networking-with-hyper-v.aspx

this should fix the misconfiguration issues and get your network working fine again.

regards
bhanu

Author

Commented:
Hi bhanu:

Thank you for your comment.

The physical NICs are fixed on the motherboard, so I can't remove them physically. Because it's Hyper-V core server, there is also no device manager interface I can use to do it using software.

Doing it by connecting to the server remotely with MMC is also impossible, because the NICs don't allow network traffic anymore.

Erik

Author

Commented:
To All:
We know of course that re-installing would solve this issue, but it is something we want to avoid.
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Cloud Architecture Manager
Commented:
hi rico,

what i meant was to uninstall and reboot which will redetect the network cards. As server core does not have GUI you can use the devcon utilility from command line and uninstall all network cards

http://support.microsoft.com/kb/311272

once you have done that you can go ahead and reconfigure the network cards either using the same devcon utility or you can use the coreconfigurator.exe

http://coreconfig.codeplex.com/

this should help you resetting the network settings.

hopefully you can try this before trying or thinking of re-install :)

Author

Commented:
Thanks bhanukir7

Thanks to your instructions it's running again!
Naga Bhanu Kiran KotaCloud Architecture Manager

Commented:
glad that i could be of help.

Commented:
Just to clarify. I was running Hyper-V R2 (server core) and in order to use devcon properly I had to use the 64bit version. I was running on Dell 2950 which has intel processors and I was not able to use the ia64 version of DEVCON. I contacted Technet Online Concierge and I was told to use the amd64 version to be able to run the 64bit version of DEVCON.

Where did I get this version? I downloaded the Windows 7 (Windows Driver Kit) and installed it on my workstation. Then I copied the DEVCON.exe version in the \Tools\devcon\amd64 folder.

This version allowed me to use alll the functionality of DEVCON on 64bit core server. The i386 version did not allow me to remove any physical NIC's. The amd64 version did.

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