hi

my question was ip multicast to mac .01-00-0E-7F-FF-FF
01-00-5E start of a multicast ip clear.

THE REST OF IT IST BLACK I GET WE NOT PERFECT

THANK

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As I mentioned in your other thread, you have to be concerned with the lower 23 bits.

The steps listed in the book that I used are as follows:

1. Write the address out in binary. For example 228.10.128.140.

11100100.00001010.10000000.11110000

2. Drop the first 9 bits and convert the rest to hex. Since this won't line up correctly I will lay it out this way.

xxxx xxxx= nothing

.x000 = 0
1010 = A
.1000 = 8
0000 = 0
.1111 = F
0000 = 0

In other words, the second octet is 0A, the third is 80, and the fourth is F0.

3. Next, prepend the OIU number which is 01-00-5E.

01-00-5E-0A-80-F0



This gives you the MAC address. Now youhave to determine the overlapping IP adresses. Take the fifth through ninth bits of the IP address and cycle through all combinations.

4. This will give you the full list of 32 IP addresses that all map to the same MAC address.


This is almost verbatim from the book, so I take no credit for this.

HTH,

Reamer

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