Changed MAC

czezz · 06-10-2008, 10:43 AM

I have V490 machine with 2 NIC.
Both NIC has this same mac-address.

Code:

ce0: flags=1000843<UP,BROADCAST,RUNNING,MULTICAST,IPv4> mtu 1500 index 2
        inet 159.107.88.63 netmask ffffff00 broadcast 159.107.88.255
        ether 0:14:4f:b8:5:f4
ce1: flags=1000802<BROADCAST,MULTICAST,IPv4> mtu 1500 index 3
        inet 0.0.0.0 netmask 0
        ether 0:14:4f:b8:5:f4

Simplly I have changed one of them with:

Code:

# ifconfig ce1 ether 0:14:4f:b8:5:f5

Last digit has been changed from 4 to 5.

Now I am wondering is there any particullar way to call new mac-address or it can be whatever I imagine ?

bhaslinux · 06-10-2008, 11:43 AM

MAC address is supposed to be unique in the world. So you cannot use a random MAC address.
But if you are sure that it is a stubbed network then you can assign some random one ; if this is not going to clash with any other NIC's MAC in your network.

redgoblin · 06-10-2008, 12:02 PM

If you're inside your own network then you can change it to pretty much what ever you like. If you break the uniqueness of it then it's only you that needs to deal with it (and that's not likely)

If you want to be more exact about it Wikipedia has a good explanation of what makes a correct MAC address. See the part on "Address Details" for an information an constructing a custom MAC address.

jlliagre · 06-10-2008, 12:04 PM

The IEEE is defining a range of addresses that are designed to be managed locally and so are guaranteed to be unique as long as you don't mess with affecting them.

These are the LAA mac addresses. The seventh bit of the first byte must be set and the eighth must be not. Or expressed differently, the first byte must be non null and even. (eg: 02:xx:xx:...)

coolster · 06-10-2008, 12:30 PM

Quote:

Originally Posted by czezz

I have V490 machine with 2 NIC.
Both NIC has this same mac-address.

Now I am wondering is there any particullar way to call new mac-address or it can be whatever I imagine ?

When your box has more than one Sun Ethernet device, all initially have the same mac address. You can change this behaviour from the OBP prompt.
The OBP variable local-mac-address? controls this. The next commands will help you to see what local-mac-address? is set to:

View local-mac-address? setting from OBP

ok printenv local-mac-address?
local-mac-address? = false

Or like this:
# eeprom local-mac-address?
local-mac-address?=false

When set to to false, all interfaces on a SPARC use the same MAC address. To change this behavior, use either of the following command
ok setenv local-mac-address?=true
local-mac-address? = true

When you adjust the command via eeprom, you may need to reboot to see the changes take affect.

regds