![]() ![]() Calculator (or Excel) tells us x = 48!īefore we rejoice in Kevin and DJ being right about 48 bits, let’s for just a moment revel in the fact that I pulled logarithms out of the very dustiest parts of my brain. Dividing both sides by log 2, we get x = 12 log 16 divided by log 2. Another cool thing about logarithms is you can tear that exponent inside the log, and off and shove it down in front of the log. So our equation because log 2 to the x = log 16 to the 12. You know how you can multiply or divide both sides of an equation and it’s still true? Turns out you can take the logarithm of both sides and it’s still true. To figure out how many bits are in a MAC address, the equation becomes 2 to the x = 16 to the 12. ![]() Still with me? The next part is my favorite part of the story. That means the number of possible outcomes is 16 raised to the power of 12. That’s 16 possible outcomes for each digit. What about this MAC address thing? As Bart explained last week, MAC addresses have 12 digits, where each digit can be 0-9 and a-f. Now that we can calculate how many bits we have where there’s only 1s and 0s. So 3 coins is 2 raised to the power of 3. What about 3 coins or bits? It turns out the answer is 2 to the power of however many of them you have. Same thing with bits, they’re 1 or 0 so two possible outcomes with one bit. A coin has heads and tails, so two possible outcomes. He explained bit by talking through flipping of a coin. I know I should already know this and I explained to him that he’s just the next in a long line of people attempting to get it to stick in my brain, but he said he was determined to get me to understand. Bart first had to explain to me what bits were. ![]() First of all, Bart wasn’t technically wrong, but DJ and Kevin are more specifically correct.īecause Bart and I are nerds, we decided to work out the answer, and actually “do the math” and see if they’re right that MAC addresses are 48 bits not 64 bits. Now this is going to sound a bit like explaining the tax code but I hope you’ll bear with me because there are a couple of parts here I think are interesting. They both explained that MAC addresses as we are used to seeing them, are 48 bits, not 64 bits. This is conveniently the length of a MAC address. In IPv6, the host part is always 64bits long. Seriously,Īnyway, they were both commenting on this statement: As always though, Bart is weird in that he actually likes to be corrected. One of the rules of this episode was that Bart only had a few days to learn the background himself so it was expected there might be errors. After the show aired, Kevin Jones DM’d me on Twitter and DJ made a comment on the blog, both with the same correction. I will try to add more and more practical examples and real life scenarios in IPv6 tutorial video series along with the theoretical explanation.In last week’s Chit Chat Across the Pond, I asked Bart to come during his off season to explain IPv6 to us. This video series will serve as a IPv6 tutorial for beginners and will help as a quick reference for advanced users. Have a look at EUI 64 conversion from MAC address video for more details and rationale.IPv6-101 video series on will start with the basic introduction to IPv6 protocol. And you are done… it’s as simple as that. Toggle universal/local bit in the MAC address.Divide the MAC address into 2 equal parts and add FE:FF in between. ![]() This conversion process can be explained in two steps. I have also explained the rationale behind the method for converting MAC address to EUI 64 address. This video explains how to derive EUI 64 form from the MAC address. These days some machines implement random number generator for deriving lower 64 bits, but still EUI64 from MAC address is a very popular and easy to use method. The higher 64 bits are taken from the router prefix or for link local address these bytes are fixed. With the help of the MAC address (which is globally unique) the interface derives lower 64bits of the address. For generating unique automatic address the machines generally use the MAC address. Description: One of the very interesting thing in IPv6 is its automatic addressing stuff. ![]()
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