I did a quick check on the IEEE site
http://standards.ieee.org/regauth/oui/oui.txt
according to the list, there are only a couple of registered OUI's that
begin with a "1". They are registered to AT&T Bell Labs ( 80-00-10 )and DEC
( AA-00-00 )and a couple of successors )
I presume these were for proprietary reasons in days of yore.
All other registered OUI's, according to the list, begin with 0.
I'm going to take a wild guess that this is by design, leaving the
application / protocol stack free to use those first couple of bits as
described in the various literature. I.e. token ring RII, multicast, etc.
Chuck
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of
Aaron
Sent: Wednesday, November 01, 2000 2:05 AM
To: [EMAIL PROTECTED]
Subject: a MAC Address Question
Hi, everyone!
I have a question about the MAC layer address, and I use the Ethernet for
making an example.
We all know that the first 3 bytes of the 48-bit MAC address are indicate
the vendor. Among the 3 bytes, the first is important, because the first 2-
bit in this byte has special meanings that are I/G bit and U/L bit.
I have a question about the following whether it is right:
when we get a MAC address, such as 0030.b6f7.3000 (Cisco),
1. Whether the I/G and U/L bit are already set to zero?
2. When a multicast packet shoud be sent to this address, the destination
address in the MAC packet header should be set to 0130.b6f7.3000?
Thank you for your help and there may be some understanding errors in the
questions.
thank you very much!
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