very basic question about MAC addresses - globally unique identifying bit

[mark hornberger]

I'm confused, and would appreciate some guidance. I'm reading "The
All New Switch Book" (Seifert & Edwards), and I'm on page 25, where
they say that, before the IEEE took over, Xerox issued some OUIs that
had their second bit equal to 1. But the examples given is that of
3COM, with 02-60-8C-xx-yy-zz, and DEC, with AA-AA-03-xx-yy-zz. But
when I translate those to binary, I get this -

02-60-8C = 0000 0010 0110 0000 1000 1110
AA-AA-03 = 1010 1010 1010 1010 0000 0011

Neither of these have "1" as the 2nd bit. So I'm misunderstanding
either the text or the proper way to convert Hex addresses to
binary. What am I not getting?

thanks

Mark

[glen herrmannsfeldt]

mark hornberger <mhorn...@gmail.com> wrote:

Second from the right. Though most CS people would number starting
from 0 at the right, or 0 at the left...

-- glen

[Albert Manfredi]

In case Glen's answer was too cryptic, they are referring to the bit
order as it is transferred across the wire over an Ethernet interface.

Over Ethernet, each byte (octet) is transmitted least significant bit
first. So in both of those examples, the second bit over the wire is
in fact set to 1.

Bert

[mark hornberger]

That makes it crystal clear. Thank you both for the info.