- In most network deployments, generated MAC addresses are appropriate. However, you might need to set a static MAC address for a virtual network adapter. The following examples show when you might set a static MAC address.
- This will leave the vEthernet interfaces on FI-A without an uplink to be pinned to and consequently they will go down. This should trigger the fabric failover mechanism for vNIC eth0 and make interface veth 704 on fabric B the active vNIC for eth0. It should also cause the MAC addresses that were learned on fabric A for eth0 to move to fabric B.
In most network deployments, generated MAC addresses are appropriate. However, you might need to set a static MAC address for a virtual network adapter.
Maintaining and Changing the MAC Address of a Virtual Machine When a virtual machine is powered on, VMware Workstation automatically assigns each of its virtual network adapters an Ethernet MAC address. MAC stands for media access control. A MAC address is the unique address assigned to each Ethernet network device. In case you select a Static MAC, it is your responsibility that they are unique. As this is a FAQ, let me explain how your VM’s get a dynamic MAC address: Each host has a pool of MAC Addresses. By default the Pool holds 256 Addresses, and when asked gives them out in a Round Robin fashion. Cisco UCS uses the name resolution policy to assign MAC addresses from the pool. To assign a MAC address to a server, you must include the MAC pool in a vNIC policy. The vNIC policy is then included in the service profile assigned to that server. You can specify your own MAC addresses or use a group of MAC addresses provided by Cisco. When initiating a Zerto Virtual Replication (ZVR) recovery operation, such as a Live Failover, or a Move, the recovery VM is assigned a MAC address for each NIC. These MAC addresses can be identical to those of the protected VM, which is the default behavior, or new MAC addresses can be generated upon recovery.
The following examples show when you might set a static MAC address.
■ | You want to ensure that a virtual network adapter always has the same MAC address. |
By default, VMware uses the Organizationally Unique Identifier (OUI) 00:50:56 for manually generated addresses, but all unique manually generated addresses are supported.
If you choose to use the VMware OUI, part of the range has been partitioned for use by vCenter Server , host physical NICs, virtual NICs, and future use.
You can set a static MAC address using the VMware OUI prefix by adding the following line to a virtual machine‘s configuration file:
In the example, <number> refers to the number of the Ethernet adapter, XX is a valid hexadecimal number between 00 and 3F, and YY and ZZ are valid hexadecimal numbers between 00 and FF. The value for XX cannot be greater than 3F to avoid conflict with MAC addresses that are generated by the VMware Workstation and VMware Server products. The maximum value for a manually generated MAC address is shown in the sample.
You must also set the address type in a virtual machine’s configuration file.
Because ESXi virtual machines do not support arbitrary MAC addresses, you must use the example format. Choose a unique value for XX:YY:ZZ among your hard-coded addresses to avoid conflicts between the automatically assigned MAC addresses and the manually assigned ones.
Vnic Mac Addresses Manual Download
It is your responsibility to to ensure that no other non-VMware devices use addresses assigned to VMware components. For example, you might have physical servers in the same subnet, which use 11:11:11:11:11:11, 22:22:22:22:22:22 as static MAC addresses. Since the physical servers do not belong to the vCenter Server inventory, vCenter Server is not able to check for address collision.
Modifying VNIC MAC Addresses
Any VNIC that a user creates can only have one MAC address. You can modify the MAC address byusing the dladm modify-vnic command. You can configure the VNICs created forkernel zones with one or more MAC addresses.
You can modify the existing MAC address of a VNIC configured on a datalink. You can eithermodify the MAC addresses of all the VNICs or selectively modify the MAC addresses of the specifiedVNICs. You can also modify the VLAN ID and the MAC address of a VNIC simultaneously.
To modify the MAC address of a VNIC, use the following command syntax:
where MAC-address is the new MAC address that you want to assign tothe VNIC.
In this example, vnic0 is assigned a specific MAC address.
To modify the MAC addresses of all the VNICs on a datalink, use the following commandsyntax:
In this command syntax, the –mrandom option is equivalent to the –mauto option. The MAC address is assigned automatically to the VNICs on a randombasis.
In this example, the MAC addresses of all the VNICs configured over the datalinknet0 are automatically modified on a random basis.
To modify the MAC addresses of VNICs on a selective basis, use the following commandsyntax:
For both the global and selective modifications, you specify random for the–m option.
Vnic Mac Addresses Manual Free
In this example, the MAC addresses of vnic0 and vnic2that are configured over the datalink net0 are selectively modified.
To modify the VLAN ID and the MAC address of a VNIC simultaneously, use the following commandsyntax:
Caution - Modifying multiple attributes of the VNICs globally might cause unexpected behavior with theVNICs. Instead, modify the multiple attributes of the VNICs separately.
Vendor Mac Addresses
In this example, the VLAN ID and the MAC address of vnic0 are modifiedsimultaneously.