Mike,
Jumping in on the back of Nigel's reply:
Canonical to Non-canonical MAC address Conversion
Break down MAC address into nibbles, (half a byte, or 4 bits)
Convert HEX digit to binary:
0 = 0000 , 1 = 0001
2 = 0010 , 3 = 0011
4 = 0100 , 5 = 0101
6 = 0110 , 7 = 0111
8 = 1000 , 9 = 1001
A = 1010 , B = 1011
C = 1100 , D = 1101
E = 1110 , F = 1111
Then reverse the pattern of bits for each nibble:
0000 = 0000 , 0001 = 1000
0010 = 0100 , 0011 = 1100
0100 = 0010 , 0101 = 1010
0110 = 0110 , 0111 = 1110
1000 = 0001 , 1001 = 1001
1010 = 0101 , 1011 = 1101
1100 = 0011 , 1101 = 1011
1110 = 0111 , 1111 = 1111
The convert back to HEX:
0000 = 0 , 1000 = 8
0100 = 4 , 1100 = C
0010 = 2 , 1010 = A
0110 = 6 , 1110 = E
0001 = 1 , 1001 = 9
0101 = 5 , 1101 = D
0011 = 3 , 1011 = B
0111 = 7 , 1111 = F
Then swap the resulting nibbles (1 with 2, 3 with 4 etc.) to
reverse each byte,
Do this for all 6 pairs of nibbles, and there you have it!
Here's a simpler table to follow, but it's best
to be able to learn how to do it from scratch, I suspect.
0 - 0
1 - 8
2 - 4
3 - C
4 - 2
5 - A
6 - 6
7 - E
8 - 1
9 - 9
A - 5
B - D
C - 3
D - B
E - 7
F - F
An example or two might help:
Token Ring Address:
40-00-37-46-00-01
Break it down into nibbles:
4 - 0 - 0 - 0 - 3 - 7 - 4 - 6 - 0 - 0 - 0 - 1
Convert them into binary:
0100 0000 0000 0000 0011 0111 0100 0110 0000 0000 0000 0001
Reverse the nibbles:
0010 0000 0000 0000 1100 1110 0010 0110 0000 0000 0000 1000
Convert back to HEX:
2 - 0 - 0 - 0 - C - E - 2 - 6 - 0 - 0 - 0 - 8
Swap each nibble in each pair of nibbles:
02-00-EC-62-00-80
And there you have it!
It doesn't matter if you start with Cannonical to Non-canonical,
it's the same
process each time. If you can handle converting a byte at a time
- it's a little
quicker than this, and after a while you can do it in your head.
(Just don't
tell people at parties - normal people regard this as really
sad!)
Here's a couple of pointers on the web:
http://www.cisco.com/warp/public/698/1.html
http://www.cisco.com/warp/public/650/37.html
More general Token Ring:
http://www.faqs.org/faqs/LANs/token-ring-faq/
Someone had a perl script that converted these things AFAIR that
they
mentioned looonnnnngg time ago on this list, might be worth a
trawl
of the archives.
Hope this helps
Regards
Pete S.
--- Original Message ---
"Nigel Taylor" <[EMAIL PROTECTED]> Wrote on
Fri, 1 Dec 2000 02:57:48 -0000
------------------
Mike,
When I was trying to get a grasp on this topic I
had some
questions a some different areas but found the White paper on
CertificationZone to make all the difference. Both the Token
ring and the
Bridging really help me grasp the topic. Of course you'll need
a
subscription to view it now. I know http://www.ccprep.com/
has some whitepapers available on there site maybe there's something
there
that can shed some light on this subject for you...
HTH
Nigel..
----- Original Message -----
From: Mike Neal <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Thursday, November 30, 2000 5:05 PM
Subject: Token Ring Bit Swapping
> Can anyone help me with Bit swapping from Token to Ethernet.
> I can't seem to grasp how it is done.
>
> Thanks,
> Mike
>
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