![]() ![]() MAC addresses are considered to be uniquely assigned worldwide. The MAC address of a system is composed of 48-bits and represented in Hexadecimal. The second half of the address (last 64 bits) is always used for Interface ID. IPv6 has three different types of Unicast Address scheme. ![]() Rule.2: If two of more blocks contain consecutive zeroes, omit them all and replace with double colon sign ::, such as (6th and 7th block): 2001:0000:3238:DFE1:63::FEFBĬonsecutive blocks of zeroes can be replaced only once by :: so if there are still blocks of zeroes in the address, they can be shrunk down to a single zero, such as (2nd block): 2001:0:3238:DFE1:63::FEFB Interface ID IPv6 provides some rules to shorten the address. Address StructureĪn IPv6 address is made of 128 bits divided into eight 16-bits blocks. Every digit in Hexadecimal can represent values from 0 to 15. To represent the values in readable format, this system uses 0-9 symbols to represent values from zero to nine and A-F to represent values from ten to fifteen. Hexadecimal is a positional number system that uses radix (base) of 16. Pay attention to link local address value.Before introducing IPv6 Address format, we shall look into Hexadecimal Number System. Let's see if this is true when I enable IPv6 support on F1/0 interface. So, the whole link-local address is going to be (abbreviated as per Lesson 55's explanation): For instance, we know that link-local's network bits are always FF80::/10. ![]() So my link-local address which uses this method to create the host bits will look like this:ĬE00: 19 FF:FEBA:0010, which is abbreviated to this form:Īdd the network portion to this construct calculated in step 2. This way we get 64-bit host portion of the IPv6 address. I will use the colon (:) as the delimiter and blocks of 2-bytes to make it compliant with the IPv6 convention. ![]() Use the MAC address after modifying the 7th bit in step 1 and inject the FFFE between OUI (first three bytes on the left) and the serial number of the adapter (first three bytes on the right). This gives us the hexadecimal value of: CE. This one must be flipped like shown below:ġ10011 10. 3):Ĭounting from left to right the 7th bit is: 110011 00. MAC address used in the example is (as per pic. In order to do that, operating system must first convert the hexadecimal number of the first byte to the binary form. Here is the detailed description of how 48 bits of MAC address becomes 64 bit host portion of IPv6 address in EUI-64 method (operating system takes care of these details itself).įlip the 7th bit (counting from left to right) in the MAC address (if it's 1 change it to 0, if it's 0, change it to 1). And the same method can be used to assign the host bits in the global address. In the EUI-64 method the operating system takes the MAC address (highlighted) and uses it to create the host bits for the link-local address by default (you can also do this manually). ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |