The same ethernet hardware (MAC) address is used by default on Sun systems with multiple ethernet interfaces. This works fine for failover load balancing or failover groups. It presents a problem when the two interfaces are connected to the same subnet.
To enable uniqe MAC addresses on multiple Sun ethernet interfaces, the BootPROM variable local-mac-address? needs to be set to true. This can be done from the ok prompt or by issuing the following command from the Solaris shell as superuser:
eeprom "local-mac-address?"=true
The quotes escape the question mark which would otherwise be interpreted as a wildcard by the shell.