Tag Archives: IPv6 addresses

IPv6: No ARP


ipv6-no-arp

You can omit unused zeros for your IPv6 addresses. Now, leading zeros can also be left off within the group. Example:

2001  :  DB8  :  21  :  111  :  0  :  0  :  0  :  1/64    will become,

2001  :  DB8  :  21  :  111  :  :  1/64 , meaning there are zeros inside those two colon (:)

You can figure out how many 16 bits missing by counting how many 16 bits left. You notice that there are 5 of them and we know that they are 8 all in all… So, to make an eight groups from 5, how many 16 bits zeros omitted?

8 – 5 = 3 , A primary operation!

So, there are 3 bits omitted… 2001  :  DB8  :  21  :  111  :  0  :  0  :  0  :  1/64

We have learned that IPv4 uses ARP to discover network, but in IPv6???… no ARP at all,… It uses a protocol called Neighbor Discovery Protocol… 😉

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Link Local Address


link-local-address

You can now manage on your IPv6 addresses. But, you will wonder, why is that their is more than one IP address found with just only one device? The answer is simple. It is put there for you to read this article.

Link Local Address always starts with FE80  :  :  … : …  .  :  ..  :  As you enable your router, this address is generated directly as one of your addresses. Now, how does the router know about your address? How was it generated?

Remember with your MAC Address? This is the one used to generate a Link Local Address. Check this:

Host A for example has a 0000.1111.1111 for its MAC Address.

First thing to do is cut that address in half. So, it becomes 0000.11 \ 11.1111..

Next, insert characters in the middle… Constantly, those characters are FFFE

The output would be: 0000.11FF.FE11.1111

then, if we are going to elaborate the binary equivalence for the above item is:

0000  0000  0000  0000  . 0001  0001  1111  1111  .  1111  1110  0001  0001. 0001  0001  0001  0001

you will count from the very left from 1 to 7… Then flip the seventh one.. example..:

0000  0010  0000  0000  . 0001  0001  1111  1111  .  1111  1110  0001  0001. 0001  0001  0001  0001

then,.. convert again back to hexadecimal like this:

0200.11FF.FE11.1111 . Omit unused zero. The output then become this with the correct separator for IPv6.

200:11FF:FE11:1111

The result is what we called Link Local Address.