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Losing connectivity when adding virtual network(s) on Enterpise Core R2

    Frage

  • I have a fresh install on new Dell PE 715's with 4 onboard Broadcom Gb adapters and 2 Dual Port 10Gb Intel CX4 adapters.  Everytime I try to add an external network for a VM, from another server, the process fails and I lose all connectivity to the Core server.  So far the only way I have gotten it back is to run netcfg -u vms_pp

    and reboot.  It doesn't matter if the adapters are DHCP or Static.  The adapters never work once I try to add them.  Ideas as to what would be causing this?

    Montag, 23. April 2012 19:30

Antworten

  • Hi,

    First of all, it is recommended that you have a read of the following guide for Hyper-V networking.

    http://blogs.technet.com/b/jhoward/archive/2008/06/16/how-does-basic-networking-work-in-hyper-v.aspx

    By the way, before you create External Virtual Network bind to the physical network adapters, please check the network adapter you used for Hyper-V host management. For example, in the following screenshot, there are two D-Link DFE-530TX PCI Fast Ethernet Adapters in Network Connections, list with details. I use “D-Link DFE-530TX PCI Fast Ethernet Adapter (rev.C)” for Hyper-V host management. 

    So when I create External Virtual Network in Hyper-V Manager, I will not use “D-Link DFE-530TX PCI Fast Ethernet Adapter (rev.C)”. 

    If I create an External Virtual Network bind to “D-Link DFE-530TX PCI Fast Ethernet Adapter (rev.C)”, I will lose connection to the Hyper-V host management. You can check the screenshot from the above blog.

    Freitag, 27. April 2012 05:44
  • When you "share withthe mangement os" the management OS is given a vNIC attached to the External Virtual Switch.

    The switch is placed between the management OS and the physical NIC, as the physical NIC becomes a port of the External Virtual Switch.

    So, the vSwitch itself does not get an IP - the vNIC given to the management OS that allows it to use the switch does.


    Brian Ehlert
    http://ITProctology.blogspot.com
    Learn. Apply. Repeat.
    Disclaimer: Attempting change is of your own free will.

    Freitag, 27. April 2012 15:14

Alle Antworten

  • Just to clarify (as it is not clear) - you don't need one External Virtual Network per VM just per physical (teamed) NIC.

    If you add the managment OS to each External Virtual Network you might be accidentially breaking your routing (multiple default gateways on the same network segment).

    Those are my best guesses without additional detail.


    Brian Ehlert
    http://ITProctology.blogspot.com
    Learn. Apply. Repeat.
    Disclaimer: Attempting change is of your own free will.

    Montag, 23. April 2012 21:12
  • Hi,

    Everytime I try to add an external network for a VM

    >> I suspect that you created an External Virtual Network bind to one physical network adapter here. If so, you may lose connection to the Hyper-V host machine if you bind the External Virtual Network to the current network adapter you used for the connection. For example, one Broadcom network adapter has IP address 192.168.1.1 and you remote desktop to this server through IP 192.168.1.1. When you bind the External Virtual Network to the network adapter has IP address 192.168.1.1, you will lose connection to the Hyper-V computer. You can try to use another network adapter for remote desktop connection.

    For more information, you can refer to:

    http://blogs.technet.com/b/jhoward/archive/2008/06/16/how-does-basic-networking-work-in-hyper-v.aspx


    Dienstag, 24. April 2012 02:30
  • Sorry, I've been in hurry.   Yes I am trying to bind an external network to  one and eventually a couple, of the physical NICs.  I have a dedicated NIC I only use for managing the server.  Anytime I try to create an external network using Hyper V network manger, I uncheck the share with host OS, click ok, it takes awhile then errors out and I lose all connectivity with the server until I forcably remove the Hyper V switch.

    Ideally I will have 1 NIC for the host OS, multiple NIC's for VM's, and multiples for the SAN.  Right now, Hyper V is breaking all of them.

    • Bearbeitet PaulMoose Dienstag, 24. April 2012 12:00
    Dienstag, 24. April 2012 11:21
  • The only way you can bind to more than one physical NIC is if you configure a team with your NIC teaming software and then attach an External Virtual Network to this team.

    My gut tells me that you are inadvertantly affecting your management NIC while attempting to do your actions, and thus losing access to the Hyper-V Managment IP.

    One thing that sometimes works for folks is to delete all virtual networks and start from the beginning, mapping out the physical NICs.  Because things simply get messed up over time, especially if folks begin to get frustrated if things are not working as they think.

    For you:

    Management NIC -> Physical NIC 0

    VM 0 NIC ->                                                                                  -> physical NIC 1

    VM 1 NIC -> External Virtual Switch -> Teaming software virtual NIC -> physical NIC 2

    Storage NIC 0 ->                                            -> physical NIC 3

    Storage NIC 1 -> Teaming software virtual NIC -> physical NIC 4

    Only the VMs should have any type of External Virtual Network.

    And, the storage NICs are also managment interfaces (technically).  So if they are not on a unique subnet that is different from the primary managment interface you can also lose connectivity due to having multiple gateways.


    Brian Ehlert
    http://ITProctology.blogspot.com
    Learn. Apply. Repeat.
    Disclaimer: Attempting change is of your own free will.

    Dienstag, 24. April 2012 14:02
  • I'm not trying any teaming, just having seperate adpaters for the Virtual Servers that are High Priority, and adapters for Low Priority Servers and Desktop VMs.

    After doing the command in my first post, rebooting then doing netcfg -c p -i vms_pp I have gotten to the point that I don't lose connectivity when adding a external adapter in Hyper V Net Mgr.

    The first time after repairing the Virtual Network, I was able to add an external adapter but when I removed it, I never got the physical NIC back in ipconfig /all.  So I repaired the Virtual Network again and now I get my adapters back in ipconfig /all when removing an external adapter. 

    Currently the only thing odd is I don't see the Microsoft Virtual Switch in ipconfig /all.  I also am in process of moving a VM over to see if the External Adapters works.  So some progress forward.  BTW this is a fresh install.

    Dienstag, 24. April 2012 14:51
  • You won't see virtual switches in "ipconfig /all" - they don't get IP addresses.

    A virtual switch just goes between the physical NIC and any VMs (if you select the managment OS checkbox then the OS get a virtual NIC).  Just like any physical workgroup switch.


    Brian Ehlert
    http://ITProctology.blogspot.com
    Learn. Apply. Repeat.
    Disclaimer: Attempting change is of your own free will.

    Dienstag, 24. April 2012 15:23
  • Hi,

    First of all, it is recommended that you have a read of the following guide for Hyper-V networking.

    http://blogs.technet.com/b/jhoward/archive/2008/06/16/how-does-basic-networking-work-in-hyper-v.aspx

    By the way, before you create External Virtual Network bind to the physical network adapters, please check the network adapter you used for Hyper-V host management. For example, in the following screenshot, there are two D-Link DFE-530TX PCI Fast Ethernet Adapters in Network Connections, list with details. I use “D-Link DFE-530TX PCI Fast Ethernet Adapter (rev.C)” for Hyper-V host management. 

    So when I create External Virtual Network in Hyper-V Manager, I will not use “D-Link DFE-530TX PCI Fast Ethernet Adapter (rev.C)”. 

    If I create an External Virtual Network bind to “D-Link DFE-530TX PCI Fast Ethernet Adapter (rev.C)”, I will lose connection to the Hyper-V host management. You can check the screenshot from the above blog.

    Freitag, 27. April 2012 05:44
  • You won't see virtual switches in "ipconfig /all" - they don't get IP addresses.

    A virtual switch just goes between the physical NIC and any VMs (if you select the managment OS checkbox then the OS get a virtual NIC).  Just like any physical workgroup switch.


    Brian Ehlert
    http://ITProctology.blogspot.com
    Learn. Apply. Repeat.
    Disclaimer: Attempting change is of your own free will.

    Virtual Switches show up in IPconfig  on my machines that are sharing the external adapter with mgmt.  Maybe that is why it isn;t showing up on this other one,

    I'm going to leave it alone as it is working after removing and reinstalling the virtual switch components.

    Freitag, 27. April 2012 14:59
  • When you "share withthe mangement os" the management OS is given a vNIC attached to the External Virtual Switch.

    The switch is placed between the management OS and the physical NIC, as the physical NIC becomes a port of the External Virtual Switch.

    So, the vSwitch itself does not get an IP - the vNIC given to the management OS that allows it to use the switch does.


    Brian Ehlert
    http://ITProctology.blogspot.com
    Learn. Apply. Repeat.
    Disclaimer: Attempting change is of your own free will.

    Freitag, 27. April 2012 15:14