MAC address changes on every reboot of VMware SD-WAN Edge

Products

• VMware

Issue/Introduction

This article provides the best practice to be followed when a MAC address is observed to be shuffling across reboots.

Symptoms:

• MAC addresses keep changing when deploying a new Virtual KVM VMware SD-WAN device.
• Interface names are shuffled around different MACs on reboot.
• Observed on SR-IOV-based interfaces.
• Observed when a default meta-data file(that does not specify MAC addresses for each interface) is used for cloud-init creation.
• Observed even when the MACs are made persistent on KVM.

 

Environment

VMware SD-WAN

Cause

This issue occurs if the meta-data file that is used for cloud-init creation does not consist of the MAC addresses defined under network interfaces.

 

This issue is because each driver, as it comes up, will scan for devices it can handle, and name them sequentially (starting from eth0, globally). So there might be a possibility where the interface order can change depending on the order of loading of the drivers (which may not be 100% stable).

 

Usually, this issue is seen in environments where there is a programmable environment to deploy the guest machines automatically.

 

Resolution

To resolve this issue, under the network-interfaces section of meta-data file, specify the interface names as the same names that VCO uses, spelled exactly (i.e. “GE1”, “GE2”, etc.), and pin each of them to a particular MAC address. The key here is that they must specify EVERY network interface that they attach if only to pin it to a MAC address.  

 

You must list every interface that you attach, and each MAC address must match one of the MAC addresses in the XML file for the VM. 

 

Example:

network-interfaces:

  GE1:

    mac_address: aa:bb:cc:dd:ee:ff

  GE2:

    mac_address: a1:b1:c1:d1:e1:f1

  GE3:

    mac_address: a2:b2:c2:d2:e2:f2

    type: static

    ipaddr: a1.b1.c1.d1

    netmask: 255.255.255.0

    gateway: a2.b2.c2.d2

  GE4:

    mac_address: a3:b3:c3:d3:e3:f3

    type: static

    ipaddr: a3.b3.c3.d3

    netmask: 255.255.255.0

    gateway: a4.b4.c4.d4

  GE5:

    mac_address: a4:b4:c4:d4:e4:f4

 

For more information see "Cloud-init Creation" section of the VMware SD-WAN Product Documentation.

Workaround:

This is an expected behavior and does not affect the functionality.

Additional Information

https://docs.vmware.com/en/VMware-SD-WAN/4.3/VMware-SD-WAN-Administration-Guide/GUID-B4505C25-7F82-4875-8974-0505A693BE04.html

Impact/Risks:

This is seen in the deployment phase before the production traffic is actually cut over to the SD-WAN device.