RE: [lwip-users] MAC Address?

[Roger Cover]

Howdy Folks,

Here is a bit of information about MAC addresses that might be
applicable to this discussion:

MAC addresses can either be "universally administered" or "locally
administered."

A universally administered address is assigned to a device by its
manufacturer. The first three octets are the Organizationally Unique
Identifier (OUI) of the manufacturer (issued by the IEEE). The remaining
octets are assigned by the manufacturer.

A locally administered address can be assigned to a device by any
network administrator. Locally administered addresses must not contain
OUIs.

Universally administered and locally administered addresses are
identifiable by the bit who's value is 2 in the most significant byte of
the address. A zero in that bit indicates a universally administered
address. A one indicates a locally administered address. For example:
02-12-34-56-78-90 is a locally administered address, 00-1B-21-11-74-58
is the address of my NIC (00-1B-21 is Intel's OUI). The IEEE will not
issue an OUI with this bit set.

Locally administered addresses are the responsibility of the network
administrator where they are used. Universally administered address are
the responsibility of device manufacturers.

>>> Are there some pre-allocated MAC addresses one can use temporarily
>>> for testing?

If you want a MAC address for testing a product under development, you
can just pick any locally administered address you want (subject to your
network administrator's guidance). If you want a MAC address for
shipping a product, you need to buy a block of addresses or buy a
company OUI. Both of them are reasonably inexpensive and can be used for
any number of products.

Regards,
Roger