Networking and Ethernet devices Ethernet MAC address issues

Ethernet MAC address issues

Some boards with these devices do not have a MAC address blown into the serial EEPROM. If this is the case a message is displayed:

eth0: Invalid ethernet MAC address. 
Please set using ifconfig

To overcome this a modification has been made to the Linux kernel, which allows the MAC address to be set up from the command line. When building the kernel, enable CONFIG_NWHW_CONFIG as follows:

Device Drivers ---> Networking Support --->
Configure network hardware from the command line

Then add the MAC address to the boot command in the form:

nwhwconf=device:<dev>,hwaddr:<addr> 

where:

• <dev> is the device name, normally eth0, and

• <addr> is the MAC address, which has the form: xx:xx:xx:xx:xx:xx,
  (xx are hexadecimal characters).

For the STEM board, a range of MAC addresses has been retrospectively allocated. The serial number of the board should be a valid MAC address.

For other boards, the MAC address to use must be unique on the local network. Consult your network administrator to find if any numbers have been locally allocated. Some ranges of addresses will not be allocated to card vendors. A list of these is available at http://www.certsoft.com/mac.htm.

To generate a MAC address, use one of the locally administrated ranges with a locally unique number; for instance the last three digits of your IP address. So, for example, using the AA0000 range with an IP address of 164.129.89.7 (hexadecimal A4 81 59 07) the MAC address generated would be AA:00:00:81:59:07.