## Forum Replies

1. This is killing me. I have a task to convert 239.192.0.1 to a mac-address. I am just not getting it right now.

01:00:5e:ef: is as far as I get…how to I convert the 100 (binary for 192 is 11000000 so I eliminate the first 1) to hex? 01:00:5e:ef:?0:00:01 is where I am at.

2. Hi James,

I understand that these calculations make your head spin…they are kinda annoying

decimal: 239.192.0.1
binary: 11101111 11000000 00000000 00000001

1. We only care about the last 23 bits of your IP address so I removed the first 9 bits, that gives us:

1000000 00000000 00000001

1. Now we need to convert these 23 bits into hexadecimal. You need to take 4 binary bits and convert them to hexadecimal:

binary: 100 0000 0000 0000 0000 0001
hex: 4 0

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3. Hi Rene,

Excellent post and excellent explanation of what should be simpler and was made unnecessarily complex

Just one small correction:

Where you say “The multicast IP addresses above all map to the same multicast MAC address (01-00-5E-01-01)”, I think you’re missing one octet. I believe it should be 01-00-5E-01-01-01.

4. Hi Rene,

Excellent creation as usual . Please confirm my understanding is correct which is grabbed from this lesson. Please let me know if I am wrong

General format of MAC address is MM:MM:MM:SS:SS:SS.The leftmost 6 digits (24 bits : MM:MM:MM ) called a “prefix” is associated with the adapter manufacturer.
The rightmost digits (24 bits : SS:SS:SS) of a MAC address represent an identification number for the specific device with the same vendor prefix.

But here in this multicast we use the leftmost 3 octets are (24 bits : MM:MM:MM) always 01-00-5E and the right

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