I have a strange problem in my office network.

I have a physical server which runs ESXi 4. Every time I reboot a linux virtual machine (Ubuntu Server 12.04.1 LTS) the entire LAN network goes down. From the router web interface in fact I can see the LAN network port (which is connected to a switch) marked as down.

The physical machine is itself connected with the switch. I had the same exact problem with Windows Servers machines but I solved it by disabling IPv6. Disabling it on linux machine does not solve the issue. Note that the ESXi 4 server IPv6 support is disabled but enabling it did not solve. Also note that other Linux or Windows 7 machine connected to the same switch does not cause this problem, even with IPv6 enabled. The shutdown of the network always happens when the ubuntu system is executing /script/local-bottom and /script/init-bottom.

I'm not a network administrator expert so even if the solution is obvious I don't really have any clue on what could cause this problem. Is this really related to IPv6? Can it be an hardware problem of the switch? Or is something that ubuntu does on startup that can expose this behaviour?

Does anyone can point me in the right direction?

  • 2
    You forgot to mention some important information, what router and switch are involved. – Michael Hampton Jan 16 '13 at 14:36
  • Do the infrastructure server (or any other software you use to monitor your ESX) show any kind of message / error log / alarm? – jap1968 Jan 24 '13 at 23:19
  • Can you watch the network traffic with wireshark and make a screenshot when it goes down? – ott-- Jan 29 '13 at 15:39

This has the ugly stench of spanning tree. Do your VMs have more than one network interface configured? If the office network comes back up after a short time, you may find some kind of internal loop is being created within your hypervisor which is making the switch disable the port because it's detected a loop with [R]STP.

| improve this answer | |
  • Looks like a spanning-tree issue to me as well. Some sort of misconfiguration on the virtual LAN and/or VM's. – Tonny Jan 29 '13 at 15:57

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