"illegal" or reserved MAC address ?

Archived from groups: comp.dcom.lans.ethernet (More info?)

aaabbb16@hotmail.com (wld) writes:

>Like IP address 10.x.x.x;172.16-31,192.x.x.x,Anyone know what "illegal"
>or reserved MAC address which can not use ?

What do you mean by "can not use"? IP addresses like 10.x.x.x are not
illegal in any useful sense. They are intended to be used - locally.

Have a look at http://www.rhyshaden.com/ethernet.htm#Frame - in Chapter 3.2
you'll find mention of the U/L bit within a MAC address, which determines
whether a MAC address is universally assigned or locally administered.
The locally administered addresses, comprising half of the whole address
space, are morally equivalent to IP layer private addresses from 10.x.x.x,
192.168.x.x, etc.

best regards
Patrick

Archived from groups: comp.dcom.lans.ethernet (More info?)

In article <41298c51$0$13015$9b622d9e@news.freenet.de>,
mailer-daemon@bof.de (Patrick Schaaf) wrote:

>
> So, question for the group: is use of the U/L bit (set to L) legal in all
> ordinary Ethernets? Is there a canonical GOOD reference that gives license
> for such usage? Or, is it just "happens to work"?
>

Setting the "U/L" bit to "L (local)" is valid, per IEEE 802.3 (about as
good a "canon" as you are likely to get). All this means is that, for
the devices so set, responsibility for unique address assignment falls
on the network administrator, rather than on the manufacturer of the
device.


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Rich Seifert Networks and Communications Consulting
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