The other option is to buy Microchip’s MAC address chips. The pre-programmed EUI-48™ enabled MAC address chips come with up to 1.5Kb of serial EEPROM that can be used to store configuration settings, routing tables or buffer small amounts of data. These plug-and-play devices come in three standard bus interfaces, I²C, SPI and UNI/O bus and feature tamper proof codes that are write-protected. Finally, they are low-cost, easy to access and come with no volume restrictions.