SPARC: How to Ensure That the MAC Address of Each Interface Is Unique

Every SPARC based system has a system-wide MAC address, which by default is used by all interfaces. However, some applications require every interface on a host to have a unique MAC address. Certain types of interface configuration such as link aggregations and IP network multipathing (IPMP) similarly require that interfaces must have their own MAC addresses.

The EEPROM parameter local-mac-address? determines whether all interfaces on a SPARC based system use the system-wide MAC address or a unique MAC address. The following procedure describes how to use the eeprom command to check the current value of the local-mac-address? parameter and change it, if necessary.

1. Become an administrator.
2. Determine whether all of the interfaces on the system currently use the system-wide MAC address.

   # eeprom local-mac-address?
   local-mac-address?=false

   In the previous output, the local-mac-address?=false setting indicates that all of the interfaces use the system-wide MAC address. You must change the value of the local-mac-address?=false setting to local-mac-address?=true before any interfaces can become members of an IPMP group, for example.

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   Note -  You should also make this change when configuring link aggregations.

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3. Change the value of the local-mac-address? setting as follows:

   # eeprom local-mac-address?=true

   When you reboot the system, the interfaces that have factory-installed MAC addresses will use these factory settings rather than the system-wide MAC address. Interfaces without factory-installed MAC addresses will continue to use the system-wide MAC address.

4. Check the MAC addresses of all of the interfaces on the system.

   Look for cases where multiple interfaces have the same MAC address. In the following example, two interfaces use the system-wide MAC address 8:0:20:0:0:1.

   # dladm show-linkprop -p mac-address
   LINK     PROPERTY        PERM VALUE        EFFECTIVE    DEFAULT   POSSIBLE
   net0     mac-address     rw   0:14:4f:f9:b1:a9 0:14:4f:f9:b1:a9 0:14:4f:f9:b1:a9 --
   net3     mac-address     rw   0:14:4f:fb:9a:d4 0:14:4f:fb:9a:d4 0:14:4f:fb:9a:d4 --
   net2     mac-address     rw   0:14:4f:f9:c:d 0:14:4f:f9:c:d 0:14:4f:f9:c:d --
   net1     mac-address     rw   0:14:4f:fa:ea:42 0:14:4f:fa:ea:42 0:14:4f:fa:ea:42 --

5. (Optional) If necessary, manually configure the remaining interfaces so that all interfaces have unique MAC addresses.

   # dladm set-linkprop -p mac-address=mac-address interface
    

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   Note -  This step is only required if two or more network interfaces have the same MAC address.

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   In the previous example, you would need to configure net0 and net1 with locally administered MAC addresses. For example, to reconfigure net0 with the locally administered MAC address 06:05:04:03:02, you would type the following command:

   # dladm set-linkprop -p mac-address=06:05:04:03:02 net0
    

6. Reboot the system.