6.7

Table Of Contents
MAC Address Management 12
MAC addresses are used in the Layer 2 (Data Link Layer) of the network protocol stack to transmit
frames to a recipient. In vSphere, vCenter Server generates MAC addresses for virtual machine adapters
and VMkernel adapters, or you can assign addresses manually.
Each network adapter manufacturer is assigned a unique three-byte prefix called an Organizationally
Unique Identifier (OUI), which it can use to generate unique MAC addresses.
VMware supports several address allocation mechanisms, each of them with a separate OUI:
n
Generated MAC addresses
n
Assigned by vCenter Server
n
Assigned by the ESXi host
n
Manually set MAC addresses
n
Generated for legacy virtual machines, but no longer used with ESXi
If you reconfigure the network adapter of a powered off virtual machine, for example by changing the
automatic MAC address allocation type, or setting a static MAC address, vCenter Server resolves any
MAC address conflict before the adapter reconfiguration takes effect.
This chapter includes the following topics:
n
MAC Address Assignment from vCenter Server
n
MAC Address Generation on ESXi Hosts
n
Setting a Static MAC Address to a Virtual Machine
MAC Address Assignment from vCenter Server
vSphere provides several schemes for automatic allocation of MAC addresses in vCenter Server. You
can select the scheme that best suits your requirements for MAC address duplication, OUI requirements
for locally administered or universally administered addresses, and so on.
The following schemes of MAC address generation are available in vCenter Server:
n
VMware OUI allocation, default allocation
n
Prefix-based allocation
VMware, Inc.
189