Problems with Virtual Network Configuration in Hyper-V

You haven't provided what is the Host OS and Guest OS ?

Assuming you have the windows hyper-v role installed.

It is a best practice to use a separate network card for Hyper-V Virtual Machines and a separate NIC for Hyper-V Host.

You can also use just one NIC too.

Now, if you have only ONE NIC, you would create a virtual network via "Hyper-V Manager" > Virtual Network Settings / Manager, set the type as "External", bind it to the NIC which is physically connected to your LAN Switch.

Once thats done, you simply create a virtual machine, go into the virtual machine settings and assign that machine that Virtual Network.

If still it doesn't work, then try using the "Legacy Adapter" for your Virtual  Machine.

Sometimes, with some nics (HP QuadPort), there have been some driver issues on R2, for which you simply remove all virtual networks, remove nics from the device manager of the host server and then reboot to let Windows detect and install them.

http://www.virtuatopia.com/index.php/Understanding_and_Configuring_Hyper-V_Virtual_Networks

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

in the VM do you have the guest NIC as showing "UP" or "not connected" or "limited connectivity"?
are you using DHCP or static IP?

The Hyper-V host has its own NIC.  (There are 4 NICs in this system - 1 for the Hyper-V host and 3 for VMs)

In the VM the NIC shows up as "limited connectivity", and it is configured to use a static IP.

FYI: This is a Win2k8 R2 server core install with the Hyper-V role enabled.

Have you made sure that the IP information is correct?
The NIC to which the VM is connected has correct IP info?
trying pinging the gateway IP address from host machine?

Regards,
Shahid

Have you tried clicking on the "Diagnose" option (right click network card and diagnose) and see if that helps ?

As Shahid has mentioned to check a few things, check them and report back.

Which network card is that ?

are you using all 3 nics as 3 different virtual networks ?

are these HP NICS ?

Once you haev verified what Shahid has asked you and if that doesn't helps at all then :

if YES, then remove the virtual network, remove the nics from the device manager (uninstall / delete drivers) and reboot, let windows detect the drivers.

I have tried "troubleshoot problem" on the VM, but that results in "Troubleshooting couldn't identify the problem."

The IP information in the VM is correct, however, the IP information of the NIC the VM is connected to is picking up a DHCP address.  To be more specific, the Broadcom BCM5709C NetXtreme II GigE (NDIS VBD Client) #4 (Which now shows up as "Ethernet adapter Local Area Connection 6:" on the Hyper-V host machine - see below) is connected to virtual network "ABC2", and VM "ABC2" is set to use virtual network "ABC2".  However, the Broadcom BCM5709C NetXtreme II GigE (NDIS VBD Client) #4 (Now LAC #6) is getting the DHCP assigned 192.168.1.105 address, but the VM it's connected to is set statically to 192.168.1.5.

And again, I'm working on a server core install, so I'm not quite sure how I'd remove the NICs from device manager.

ipconfig /all from Hyper-V host:

Windows IP Configuration

   Host Name . . . . . . . . . . . . : abc1
   Primary Dns Suffix  . . . . . . . : acme.com
   Node Type . . . . . . . . . . . . : Hybrid
   IP Routing Enabled. . . . . . . . : No
   WINS Proxy Enabled. . . . . . . . : No
   DNS Suffix Search List. . . . . . : acme.com

Ethernet adapter Local Area Connection 6:

   Connection-specific DNS Suffix  . : acme.com
   Description . . . . . . . . . . . : abc2
   Physical Address. . . . . . . . . : A4-BA-DB-08-B9-00
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::d9d2:1e5e:f286:1ec8%316(Preferred) 
   IPv4 Address. . . . . . . . . . . : 192.168.1.105(Preferred) 
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Lease Obtained. . . . . . . . . . : Tuesday, April 13, 2010 3:30:08 PM
   Lease Expires . . . . . . . . . . : Wednesday, April 21, 2010 3:30:09 PM
   Default Gateway . . . . . . . . . : 192.168.1.1
   DHCP Server . . . . . . . . . . . : 192.168.1.8
   DHCPv6 IAID . . . . . . . . . . . : 1067760347
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-13-3C-4B-9F-A4-BA-DB-08-B9-02
   DNS Servers . . . . . . . . . . . : 192.168.1.22
                                       192.168.3.4
                                       192.168.2.4
                                       192.168.40.5
   NetBIOS over Tcpip. . . . . . . . : Enabled

Ethernet adapter Local Area Connection 3:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . : 
   Description . . . . . . . . . . . : Broadcom BCM5709C NetXtreme II GigE (NDIS VBD Client) #3
   Physical Address. . . . . . . . . : 00-10-18-6A-EA-D2
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes

Ethernet adapter Local Area Connection 2:

   Media State . . . . . . . . . . . : Media disconnected
   Connection-specific DNS Suffix  . : 
   Description . . . . . . . . . . . : Broadcom BCM5709C NetXtreme II GigE (NDIS VBD Client) #2
   Physical Address. . . . . . . . . : 00-10-18-6A-EA-D0
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes

Ethernet adapter Local Area Connection:

   Connection-specific DNS Suffix  . : 
   Description . . . . . . . . . . . : Broadcom BCM5709C NetXtreme II GigE (NDIS VBD Client)
   Physical Address. . . . . . . . . : A4-BA-DB-08-B9-02
   DHCP Enabled. . . . . . . . . . . : No
   Autoconfiguration Enabled . . . . : Yes
   Link-local IPv6 Address . . . . . : fe80::a8b5:46ab:1edf:6fb3%3(Preferred) 
   IPv4 Address. . . . . . . . . . . : 192.168.1.4(Preferred) 
   Subnet Mask . . . . . . . . . . . : 255.255.255.0
   Default Gateway . . . . . . . . . : 192.168.1.1
   DHCPv6 IAID . . . . . . . . . . . : 61127387
   DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-13-3C-4B-9F-A4-BA-DB-08-B9-02
   DNS Servers . . . . . . . . . . . : 192.168.1.22
                                       192.168.2.4
   NetBIOS over Tcpip. . . . . . . . : Enabled

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have you tried setting the VM to get DHCP IP?

Yes I have set the VM to DHCP, but the VM still can't get an address.  

As I've mentioned before, at first this system reported 4 physical adapters via ipconfig (adapters 1, 2, 3 and 4).  Then, after creating a virtual network in Hyper-V, adapter 4 disappeared and “local area connection 6” appeared (I’ll call it “LAC6” from here on out), and LAC6  had grabbed a DHCP address.  However, after configuring the VM to use the virtual network that was bound to physical adpater #4  (Now LAC6), I was unable to establish any network connectivity.  I would think the new LAC6 would reflect the settings of the VM, but that is not the case.  The VM can have a static address, while LAC6 can be set to DHCP.  What's the best practice here?  How can the VM have one address, and the physical NIC that the VM talks through have another?

"How can the VM have one address, and the physical NIC that the VM talks through have another?"
Infact, this is the way it should be. You don't need to do anything special to achieve that specially when you are using host and VM are on the same subnet.
This is strange.

Can you send the screen shot of the VM settings
Can you list the output of ipconfig/all on the Guest VM

Regards,
Shahid

Here you go:
VMIpconfig.jpg
HyperVsettingforVM.jpg
VN.jpg

Have you tried adding another NIC to the VM and see if that helps?
tried both network adapter and legacy network adapter

Regards,
Shahid

So are you saying I should try to create another virtual network bound to another NIC, and then add that to the VM?

Yes, that would help us isolate the problem.
Can you do that?
please share the results.

Regards,
Shahid

I've tried creating other virtual networks, but that made no difference.

I do think I'm on to something though - I've notice that the switch port the virtual machine is plugged into on my Catalyst 2960 often times goes into err-disabled mode.  Given that, I then connected both the NIC attached to the parent partition and the NIC attached to the VM into a hub, and WAS able to ping to the other.  After a doing a little research I came to the conclusion that “port security” on the switch may have had something to do with the problem.  However, after disabling port security, the port did NOT go into err-disabled mode, but it also would not allow any pings.

Any ideas?