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No network connection between multiple VM's RRS feed

  • Question

  • Hi folks hope you could help me.

    Searched different fora but could not find a solution that was related to my problem?

    Situation:
    I have 2 network cards in my machine. 1 broadcom used by the machine itself (not used by hyper V)

    I used the second networkcard (Intel i219-V Gigabit) as my "external network" in the switchmanager so i could communicate between 3 VM's (server 2016) and a laptop hooked up directly with crosslink to the newtwork card.
    All 3 VM's use static Ip adresses, since 1 of the VM's is a DC with DHCP on it and should give network adres to laptop. (That works fine)

    Reason for that being that i'm studying for SCCM 2016 and i need to deploy to real machine for testing bios WMI query's

    Now my problem is that my connection between the VM's is showing "no connection", but once i put power on the laptop and thus also on the external network then the virtual networkcards from the VM's show connected.

    This is really annoying since of course i want them also to be "connected" without the use of the external laptop.
    There is also no hardware switch being used.

    It's like there is no virtual power on the virtual networkcards or no activity?
    Hope i explain myself in a usefull way?

    Hope someone could give me a permanent fix or a workaround.

    Thanks




    • Edited by BelgianGuy Sunday, October 20, 2019 11:20 AM
    Sunday, October 20, 2019 11:06 AM

Answers

All replies

  • This is really annoying since of course i want them also to be "connected" without the use of the external laptop. 

    The external vSwitch the VMs use should be plugged into port of physical switch that provides route to internet. Domain controller and domain members should have the static ip address of DC. Internet queries would be passed on to 13 default root hint server in a top-level down fashion or optionally configured forwarders.

     

     

     

     



    Regards, Dave Patrick ....
    Microsoft Certified Professional
    Microsoft MVP [Windows Server] Datacenter Management

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees, and confers no rights.


    Sunday, October 20, 2019 1:02 PM
  • I don't agree with that

    My "external network" is setup because it's the only option to be used with an external nic. But should also be able to have activity when the external network is not being used.

    Second to that i'm talking about network activity not internet activity.
    My network has no internet, and it doesn't need to

    Once i power the external laptop then it also "power up" the virtual networkcards on the VM's?!!!! Like in the real world, when you have 10 devices on a switch and 2 are not powered up, it should not affect the remaining devices. 2 (minimum) devices should be enough to bring the network alive.

    So I believe your answer is not related to my question, sorry

    Regards

    PS: To bad i'm not able to insert images until i'm verified?!


    • Edited by BelgianGuy Monday, October 21, 2019 5:26 AM
    Monday, October 21, 2019 4:53 AM
  • Hi,

    Thanks for your question.

    Now I understand your current situation that you'd like the 3 VMs can communicate with Laptop and assign IP to it. But the network on the VMs loss connection when the loptop power off, is that right?

    Did the other two VMs and the loptop join into the VM's domain? 

    Did the VM DC disconnect when the loptop power off?

    Meanwhile, based on my experience, due to the VMs connect to external network type and it connect simply with the laptop. When laptop power off, the server NIC connected to it will disconnect, then the VMs would loss the connection on the external network. YOu could check the host server's NIC connected to the laptop, if it disconnected when the laptop power off.

    In addition, your opinion for that when you have 10 devices on a switch and 2 are not powered up, it should not affect the remaining devices. 2 (minimum) devices should be enough to bring the network alive. Yes, I agree with you, it's right indeed.

    Hope this helps. If you have any question or concern, please feel free to let me know.

    Best regards,

    Michael


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    Monday, October 21, 2019 8:08 AM
    Moderator
  • Hi Michael yes you are correct.

    I like the 3 vm's to communicate with eachother even when the laptop is power off.

    Now i just tested and idd the 3 VM's loose connection as soon (read as immidiately) as the power is off on the laptop. And like i said i assume a virtual switch would replicate a real switch so the 3 VM's should be able to communicate regardless if the laptop is powered off or on.
    But then immidiately they go on "not connected - no connections available"

    The 3 VM's are all joined to the domain, and have all static adresses.
    But to be honnest this looks more like real pc's who don't have an actual cable plugged in and thus no power on the card.

    So it's nothing to do with bad Vlan's or bad ip adresses. Once i power up the laptop then ALL can communicate perfectly.

    I don't believe that hyper V external network is build that there needs to be always a powered device on the line before your entire network is able to work.

    Is there a way i can verify my account so i can upload pictures? I can't seem to find that info in the forum rules?



    • Edited by BelgianGuy Monday, October 21, 2019 9:29 AM
    Monday, October 21, 2019 9:28 AM
  • I like the 3 vm's to communicate with eachother even when the laptop is power off.

    Might also try using a private or internal vSwitch

    https://blogs.technet.microsoft.com/jhoward/2008/06/17/hyper-v-what-are-the-uses-for-different-types-of-virtual-networks/

     

     



    Regards, Dave Patrick ....
    Microsoft Certified Professional
    Microsoft MVP [Windows Server] Datacenter Management

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees, and confers no rights.

    Monday, October 21, 2019 12:51 PM
  • "Now i just tested and idd the 3 VM's loose connection as soon (read as immidiately) as the power is off on the laptop."

    Check the power management settings on the NIC.

    You might also need to check with Intel.  They may have the NIC set up that it doesn't work unless it is connected.  My guess if you put a loop back adapter on it, then it would work.  Simple thing to try.  From Hyper-V's perspective, my hunch is that the virtual switch is considered inoperable if the NIC to which it is assigned is considered inoperable.


    tim

    Monday, October 21, 2019 2:34 PM
  • "I like the 3 vm's to communicate with eachother even when the laptop is power off.

    Might also try using a private or internal vSwitch"

    That won't work, since in a private or internal vswitch you cannot connect an external network thus unable to connect the laptop to that network whenever i want (for testing)

    Monday, October 21, 2019 5:09 PM
  • Then I'd try putting an unmanaged switch in between host NIC and the laptop. 

     

     



    Regards, Dave Patrick ....
    Microsoft Certified Professional
    Microsoft MVP [Windows Server] Datacenter Management

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees, and confers no rights.

    Monday, October 21, 2019 5:22 PM
  • Hi Tim, you are in the right direction.

    I just tested with a small 5 port Dlink unmanaged switch and guess what. No laptop connected so just UTP cable between nic and switch and all VM's have network.

    So indeed HyperV deactivate the external virtual lan once it doesn't "feel" a connection on my/the external nic.

    So anymore settings i can try? The network card used in primary post is wrong (don't know where i got that, must have been sleepy lol)

    The nework card used is Intel I-217LM

    Next test that i will do is with the realtek onboard, but i've heard the realtek's don't have good score with HyperV

    Best regards



    • Edited by BelgianGuy Monday, October 21, 2019 5:53 PM
    Monday, October 21, 2019 5:23 PM
  • This is expected behavior. The brand/model of the NIC is irrelevant. 

    The external virtual switch needs an "active" NIC, the NIC must be plugged into something.  You should be able to use a physical loopback adapter if you don't have a switch to plug into.

    Monday, October 21, 2019 11:11 PM
  • This is expected behavior. The brand/model of the NIC is irrelevant. 

    The external virtual switch needs an "active" NIC, the NIC must be plugged into something.  You should be able to use a physical loopback adapter if you don't have a switch to plug into.

    Why would that be "expected behavior"?!
    If you disconnect in the real world 1 pc from your network the other pc's also don't go suddenly down.
    The 3 vm's in my opinion should have connection to each other regardless of the laptop being fysically connected or not. It's called a virtual switch for that, because it should emmulate a REAL switch so i expect it to behave like that.


    • Edited by BelgianGuy Tuesday, October 22, 2019 9:12 AM
    Tuesday, October 22, 2019 8:10 AM
  • You should not compare virtual and physical network as they are completely different technologies. The idea of external virtual switch is that it is connected to a physical network (physical switch) and not directly to a computer.

    Anyway I've tested on a Windows Server 2019 Hyper-V server and noticed that my VM's stay connected even if I physical unplugged the network adapter, but I know that I've seen this behavior on older versions of Hyper-V. What version of Hyper-V / Windows Server are you using? 

    If using a dummy physical switch fixes your problem is that not acceptable? 


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    Tuesday, October 22, 2019 8:47 AM
  • Hi Matej,

    My Hyper V is the latest build in Windows 10, driver for nic is also latest for Intel card.
    The fact that you can unplug your nic and your vm's stay connected let's me think that my network card is the problem.

    Yes i can solve it with a small real switch, and it's working.

    But i'm an IT guy and i wanna solve this for real and i wanna know what the problem is to learn from it.
    Can annyone else do the test with 2vm's and 1 external nic disconnected if it works?

    That's the whole idea of technet, to learn and to solve problems the correct way. Not to have a workaround ;-)

    Thanks

    Tuesday, October 22, 2019 9:20 AM
  • Please guys read clearly the answers, and don't just answer to answer.

    I know i can solve it with a loopback or an external switch.
    However you say a nic always have to stay active, although Matej just confirmed he's network stays active even after DISCONNECTING his nic.

    So your info is contradicting.

    Also the link you send me to verify is no longer working since that topic has been closed and you cannot reply anymore. So this question still remains open and i still cannot find info.
    Only info i can find is if someone gives me points or a single point for that matter it will become active automatically.
    Would have been easier if i could have link pictures from the start in this topic. :-)

    Regards

    Tuesday, October 22, 2019 12:50 PM
  • Would have been easier if i could have link pictures from the start in this topic. :-)

    Your new account just needs to be verified. You can expedite verification by replying to this thread with your request.
    https://social.msdn.microsoft.com/Forums/en-US/dc4002e4-e3de-4b1e-9a97-3702387886cc/verify-account-42?forum=reportabug
    Sticky located at top of Forums Issues (not product support) forum
    https://social.msdn.microsoft.com/Forums/en-US/home?forum=reportabug

     

     




    Regards, Dave Patrick ....
    Microsoft Certified Professional
    Microsoft MVP [Windows Server] Datacenter Management

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees, and confers no rights.

    • Marked as answer by BelgianGuy Tuesday, October 22, 2019 1:45 PM
    Tuesday, October 22, 2019 12:57 PM
  • My Hyper V is the latest build in Windows 10, 

    You'll find more windows 10 desktop hyper-v experts over here in dedicated forums.

    https://social.technet.microsoft.com/Forums/en-US/home?forum=win10itprovirt

    To the issue if you thinks it's hardware related then better to ask the laptop or hardware manufacturer for help.

     

     



    Regards, Dave Patrick ....
    Microsoft Certified Professional
    Microsoft MVP [Windows Server] Datacenter Management

    Disclaimer: This posting is provided "AS IS" with no warranties or guarantees, and confers no rights.

    Tuesday, October 22, 2019 1:02 PM