Active Directory DHCP Having Issues with Changing Port Groups in VMWARE

Matthew Urasaki 0 Reputation points
2024-01-22T23:16:02.79+00:00

Hello, We are running the following setup. Windows Server VMWare VM running AD DHCP Server Arista DHCP Relay What I have noticed is that when I change the network adapter port group on a virtual machine before boot, it receives the correct IP address from AD DHCP on its network However, if I attempt to change the network adapter to a a different port group, the same DHCP lease from the original port group is assigned to the VM Even after rebooting, the same IP address will be assigned and the only way to pull the correct IP is to add a network adapter. Our Arista switches are configured in an MLAG and at one point, I noticed that a VMs DHCP server was one of the Arista switches so this makes me think that this is a DHCP relay issue on the Arista. Outside of the helper addresses on the switches, this is the only other command on the aristas. ip dhcp relay always-on I have not seen anything in DHCP server settings that would cause this issue.

Windows DHCP
Windows DHCP
Windows: A family of Microsoft operating systems that run across personal computers, tablets, laptops, phones, internet of things devices, self-contained mixed reality headsets, large collaboration screens, and other devices.DHCP: Dynamic Host Configuration Protocol (DHCP). A communications protocol that lets network administrators manage centrally and automate the assignment of Internet Protocol (IP) addresses in an organization's network.
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  1. Hania Lian 10,531 Reputation points Microsoft Vendor
    2024-01-24T02:40:39.19+00:00

    Hello, Thank you for posting in Q&A forum. The "ip dhcp relay always-on" command on the Arista switches is used to enable DHCP relay agent on the switch and seems good. As you mentioned, this issue could be due to a DHCP relay issue on the Arista switch. From Windows aspects, I will recommend you check some basic settings: 1.Check if DHCP lease duration is set to a reasonable value. If the value is too large, the VM may retain its IP address even when moved to a different port group. 2.Check if there's any DHCP reservation which could also lead to some issue. 3.You can also capture a network trace when reproducing the issue, and run ipconfig /release and ipconfig /renew command and see if there's any issue with the DHCP traffic and where it is stuck. In this way you will be able to narrow down the issue and check it further. Best Regards, Hania Lian

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