System Administration Guide: IP Services

ProcedureSPARC: How to Ensure That the MAC Address of an Interface Is Unique

Use this procedure for configuring MAC addresses.

Some applications require every interface on a host to have a unique MAC addresses. However, every SPARC based system has a system-wide MAC address, which by default is used by all interfaces. Here are two situations where you might want to configure the factory-installed MAC addresses for the interfaces on a SPARC system.

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

  1. On the system with the interfaces to be configured, assume the Primary Administrator role or become superuser.

    The Primary Administrator role includes the Primary Administrator profile. To create the role and assign the role to a user, see Chapter 2, Working With the Solaris Management Console (Tasks), in System Administration Guide: Basic Administration.

  2. Determine whether all interfaces on the system currently use the system-wide MAC address.

    # eeprom local-mac-address?

    In the example, the response to the eeprom command, local-mac-address?=false, indicates that all interfaces do use the system-wide MAC address. The value of local-mac-address?=false must be changed to local-mac-address?=true before the interfaces can become members of an IPMP group. You should also change local-mac-address?=false to local-mac-address?=true for aggregations.

  3. If necessary, change the value of local-mac-address? as follows:

    # eeprom local-mac-address?=true

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

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

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

    ifconfig -a
    lo0: flags=1000849 <UP,LOOPBACK,RUNNING,MULTICAST,IPv4> mtu 8232 index 1
          inet netmask ff000000  
    hme0: flags=1004843 <UP,BROADCAST,RUNNING,MULTICAST,IPv4> mtu 1500 index 2
          inet netmask ffffff80 broadcast
          ether 8:0:20:0:0:1 
    ce0: flags=1004843 <UP,BROADCAST,RUNNING,MULTICAST,IPv4> mtu 1500 index 2
          inet netmask ffffff80 broadcast
          ether 8:0:20:0:0:1 
    ce1: flags=1004843 <UP,BROADCAST,RUNNING,MULTICAST,IPv4> mtu 1500 index 2
          inet netmask ffffff80 broadcast
          ether 8:0:20:0:0:1

    Note –

    Continue to the next step only if more than one network interface still has the same MAC address. Otherwise, go on to the final step.

  5. If necessary, manually configure the remaining interfaces so that all interfaces have unique MAC address.

    Specify a unique MAC address in the /etc/hostname.interface file for the particular interface.

    In the example in Step 4, you would need to configure ce0 and ce1 with locally administered MAC addresses. For example, to reconfigure ce1 with the locally administered MAC address 06:05:04:03:02, you would add the following line to /etc/hostname.ce1:

    ether 06:05:04:03:02 

    Note –

    To prevent any risk of manually configured MAC addresses conflicting with other MAC addresses on your network, you must always configure locally administered MAC addresses, as defined by the IEEE 802.3 standard.

    You also can use the ifconfig ether command to configure an interface's MAC address for the current session. However, any changes made directly with ifconfig are not preserved across reboots. Refer to the ifconfig(1M) man page for details.

  6. Reboot the system.