[SunHELP] MACs and Servers with more than one network card on same network!

[Dale Ghent]

On Fri, 6 Apr 2001, Foong, Tzeweng wrote:

| Hi All,
| 
| I have been told that the MAC address on network cards are the same 
| for sun sparc machines !!  They somehow (How?) get their MAC address 
| synchronised (provided by) on the motherboard. 

The ethernet address is stored in and derived from the PROM. It and tha
hostid are related.

| Therefore how would it be posible to have 2 network cards on the same 
| network?? 

Sure. Read on...

| I understand that the MAC address can somehow (How? anyone know?) 
| be changed to another address so that the 2 network cards can be 
| put on the same network. Also what would you change the Mac 
| address to? I thought that these addresses are in some fixed sequence 
| so that any 2 cards would not have the same MAC. But some how Sparc
| architecture makes any network cards on the same machine the same.!!

You can change the ethernet (MAC) address of any ethernet interface with
the ifconfig command:

ifconfig <interface> ether <new MAC address>

See the ifconfig man page for more details.

As for what MAC address you can/should change it to... you can make it any
hexadecimal MAC address you want, as long as it doesnt interfere with any
other one on your local net.

If the machine you have has a PCI QFE or HME card, you can set the
following variable in the PROM (at the 'ok' prompt) and when you boot, the
QFE/HME interfaces will assume their own ethernet address that is
different from the system's default:

setenv local-mac-address? true

/dale