none IP Address Conflicts on the network, VMs lose network after reboot


  • We are having a strange issue happen on our network which appears to be affecting most hosts and VMs which is a combination of a Windows 2012 Hyper-V Cluster and Standalone Windows 2008 R2 Hyper-V Hosts.

    Prior to implementing the Windows 2012 Hyper-V Cluster we did not have the issue. That said, previously we did not use NIC Teaming either.

    The problem appears during the gratuitous ARP request during a reboot for any Physical server or VM that are running Windows 2008 R2 & 2012. The Host or VM gets a conflict with a address and then assigns itself a 169.254.X.X IP address. The conflict arises from the uplink Trunk port MAC address from a Cisco Switch. The conflict MAC address randomly changes and can be from any of uplink Trunk MACs from all access switches in the network. I can not reproduce the issue on a Windows 2003 box but this likely because Microsoft changed how gratuitous ARP works since Windows 2008.

    We are using NIC teaming with switches that were created at the Host level not in SCVMM 2012 SP1.

    Portfast is enabled for all end devices.

    Any help would be great!

    • Edited by ColeThompson Monday, January 6, 2014 6:53 AM Too much info.
    Sunday, January 5, 2014 12:14 AM


  • We have determined the problem to be caused by a recent Cisco Catalyst IOS upgrade that globally turns on 'ip device tracking'. This happens in Cisco IOS version 15.X.

    The ip device tracking in combination with how Windows 2008 and higher handles gratuitous ARP is what causes the issues.

    You can see if you have ip device tracking enabled by running the command below on your switch. The device will show ‘ip device tracking’.

    Show config | inc tracking

    Cisco References

    Cisco recommends that you modify the probe delay which we tried but this did not fix our situation.

    ip device tracking probe delay 10

    We had to run the following commands on each switch.

    int range gig0/1 - 24
    ip device track max 0

    You can confirm you have fixed the problem by downloading Xarp and running it on a host or VM connected to your network. When fixed the alerts will be gone.

    • Marked as answer by ColeThompson Monday, January 6, 2014 6:54 AM
    Monday, January 6, 2014 6:52 AM

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