Range-Based MAC Address Allocation and Recycling Policies in vCenter Server

Products

• VMware vCenter Server

Issue/Introduction

This article provides information on the management of MAC addresses within vCenter Server, including the configuration of range-based allocation, the recycling of addresses, and requirements for unique MAC addresses for virtual machines.

Environment

VMware vSphere 7.x

VMware vSphere 8.x

Resolution

MAC Address Range Configuration

vCenter Server supports range-based MAC address allocation, allowing administrators to restrict the pool of addresses available for virtual machines.

1. Navigate to the vCenter Server instance settings.
2. Select the configuration section for MAC address allocation.
3. Define the explicit start and end MAC address range.
4. Apply the settings.

Once configured, vCenter Server assigns MAC addresses only from within the specified range.

MAC Address Recycling

vCenter Server automates the management of MAC addresses to ensure efficient utilization within the defined environment.

• When a virtual machine (such as a Horizon Instant Clone) is deleted, the assigned MAC address is released back into the available pool.
• vCenter Server subsequently reassigns the released MAC address to newly created virtual machines.

Unique MAC Address Requirements

vSphere requires every active virtual Network Interface Card (vNIC) on a network to maintain a unique MAC address to prevent network collisions.

• The system enforces uniqueness by preventing multiple active virtual machines from sharing the same MAC address.
• Ensure that the defined range is sufficiently large to accommodate the maximum number of concurrent virtual machines in the environment.

Additional Information

For further details on vSphere networking and MAC address generation, review the official documentation: vSphere Networking - MAC Address Generation