none
Network Adapters on Virtual Machines not working RRS feed

  • Question

  • I have Hyper V Server 2008 sp1 installed.  

    The host has 2 network cards.   My internal network is using the 192.168.10.x addresses.  4 entries are showing up when I look at network settings menu option:

      11    192.168.10.7    Broadcom BCM5709C NetXtreme II GigE (NDIS VBD Client)
      12    192.168.10.112  Broadcom BCM5709C NetXtreme II GigE (NDIS VBD Client)
      18    169.254.54.102  Microsoft Virtual Network Switch Adapter #2
      19    169.254.148.118 Microsoft Virtual Network Switch Adapter #3

    Best I can tell all the networking to the Host are working ok.   I can ping public and internal addresses.

    I created two virtual networks in the Virtual Network Manager.   One that allows host interaction and one that does not.

    I have a VM that appears to be working great with the integration services installed (Except the network doesnt work).

    I have added a "network adapter" and assigned it to the Virtual Network without host interaction.

    I get an IP address assigned in the VM of 169.254.9.249. 

    Networking doesnt work.

    I dont really know what to look at next.

    Any help would be great.

     

    Thanks!

     

     

    Friday, April 15, 2011 5:26 AM

Answers

  • Ok, I got it.

    I logged into the Hyper Visor Server and did a "ipconfig /all" showing all the network adapters.   It seems that each virtual network adapter is assigned to an IP address ... this subnet seems to be used to assign an IP to your VM.   So, insted of picking the 1st or 2nd or 3rd network adapter,  I had to pick the 7th network adapter (Just how my hyper v server decided to assign the virtual network devices).   Unfortunately, its unclear that picking an adapter will put you on either a 192.168 subnet or a 169.254 subnet.   It would be great to make this more clear in the virtual network tool ... include the subnet that will be assigned to the VM.

    So, before you pick an adapter for your virtual network, go double check its IP and make sure its on the subnet you want.

    Thanks.

    Friday, April 15, 2011 6:22 PM

All replies

  • Hi!

    If you want your VM's to be able to connect to the internet or your LAN, you need to create a external virtual network.

    If you want your VM's only to communicate with other VM's, you need to setup your private network infrastructure like you would a physical, with DHCP and such.

    Friday, April 15, 2011 5:44 AM
  • Hello.

    Let`s have a short guide on how the virtual networks in Hyper-V works.

    1. Internal

    This is the network you want to create if you want to have communication between your VMs and your Hyper-V host. This will create a virtual NIC in the parent partition as well, that you would need to configure with proper IP and subnet to communicate with your VMs connected to this network. Rule of thumb: Networking is still networking.

    2. Private

    This is - as Mike stated, only intended for VMs. There is no link to a physical NIC on the parent partition. In other words, the VMs connected to this network, will be on an isolated network, with no access to LAN/internet. If you want to set up a Private virtual network, you will need to configure a DHCP server on this network to assign your VMs with IP,subnet, DNS etc automatically. Or, you can configure this manually. Rule of thumb again: networking is still networking, but this one is an isolated one.

    3. External

    When you create an External Virtual Network in Hyper-V, you are binding this network to a physical NIC on the parent partition. It will function as a virtual switch for the VMs connected to this network. When a VM is connected to an External Virtual Network, it should be able to communicate on the LAN/internet, if the network is configured for this. Again, it`s pure networking, and to have your VMs assigned with IP automatically, they would need a DHCP service on this network, just as if they were physical machines.

    Regards,


    Kristian (Virtualization and some coffee: http://kristiannese.blogspot.com )
    Friday, April 15, 2011 8:24 AM
  • In the Hyper-V Manager Client I used the Virtual Network Manager to create a network called "VirtualMachineNetwork".   Its configured as

    • "External" - I want the virtual machines to see my domain and the internet.
    • I have not checked "Allow management operating system to share this network adapter".

    The "VirtualMachineNetwork" is used in my Virtual Machines synthetic network adapter.

    Is there anything else I need to check/create? 

     

    Thanks guys for the help.

     

    Greg.

    Friday, April 15, 2011 2:43 PM
  • I don't know if your situation is the same as mine, but I just had an issue where my guests had no connectivity:

    http://social.technet.microsoft.com/Forums/en-US/winserverhyperv/thread/a7fcac64-5164-4312-ab9d-af40435dd5a3

    To add a little detail to my final solution:

    I started my two guests, they both got 169.254.x.x addresses and couldn't contact anything (not even each other).

    I changed the virtual network from external to private and suddenly they could ping each other.

    I changed the network back to external and they continued to work.

    I have no idea why this worked or why the problem even existed in the first place as this was a brand new install on a box that previously ran Hyper-V with no issues.

    Friday, April 15, 2011 3:00 PM
  • I gave that a try.   Now my VM is getting a 169.254.x.x address.   I can now ping the host, but nothing else.   I tried manually setting to a 192.10.x.x address, but no luck.

    Any other ideas?

     

    Friday, April 15, 2011 3:42 PM
  • I noticed that the virtual adapter was set to "internal".   I did more testing.  

    An "Internal" virtual network is letting me ping the host, but nothing outside (This seems ok).

    An "External" virtual network only allows me to ping the host, but no outside IP's.   I still get a 169.254.x.x address ... this doesnt seem right.

    An "External" virtual network with out "Allow management OS to share this adapter" doesnt let me ping the host or a 192.168.x.x address.

     

    I am really stuck on what to try next.

     

    My only other thought is to try to create the VM on anther instance.   

     

    Thanks.

     


    Friday, April 15, 2011 4:14 PM
  • Ok, I got it.

    I logged into the Hyper Visor Server and did a "ipconfig /all" showing all the network adapters.   It seems that each virtual network adapter is assigned to an IP address ... this subnet seems to be used to assign an IP to your VM.   So, insted of picking the 1st or 2nd or 3rd network adapter,  I had to pick the 7th network adapter (Just how my hyper v server decided to assign the virtual network devices).   Unfortunately, its unclear that picking an adapter will put you on either a 192.168 subnet or a 169.254 subnet.   It would be great to make this more clear in the virtual network tool ... include the subnet that will be assigned to the VM.

    So, before you pick an adapter for your virtual network, go double check its IP and make sure its on the subnet you want.

    Thanks.

    Friday, April 15, 2011 6:22 PM