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IPv6 Address and Address Notation and Prefix Representation
(Page 1 of 4)
Increasing the size of IP addresses
from 32 bits to 128 bits expands the address space to a gargantuan size,
ensuring that we will never again run out of IP addresses, and allowing
us flexibility in how they are assigned and used. Unfortunately, there
are some drawbacks to this method, and one of them is that 128-bit numbers
are very large, which makes them awkward and difficult to use.
IPv6 Addresses: Too Long For Dotted Decimal Notation
Computers work in binary, and they
have no problem dealing with long strings of ones and zeroes, but humans
find them confusing. Even the 32-bit addresses of IPv4 are cumbersome
for us to deal with, which is why we use dotted
decimal notation for them unless we need
to work in binary (as with subnetting). However, IPv6 addresses are
so much larger than IPv4 addresses that even using dotted decimal notation
becomes problematic. To use this notation, we would split the 128 bits
into 16 octets and represent each with a decimal number from 0 to 255.
However, we would end up not with 4 of these numbers, but 16.
A typical IPv6 address in this notation would appear as follows:
128.91.45.157.220.40.0.0.0.0.252.87.212.200.31.255
The binary and dotted decimal representations
of this address are shown near the top of Figure 95.
In either case, the word “elegant” doesn't exactly spring
to mind.
Figure 95: Binary, Decimal and Hexadecimal Representations of IPv6 Addresses The top two rows show binary and dotted decimal representations of an IPv6 address; neither is commonly used (other than by computers themselves!) The top row of the lower table shows the full hexadecimal representation, while the next two rows illustrate zero suppression and compression. The last row shows mixed notation, where the final 32 bits of an IPv6 address are shown in dotted decimal notation. This is most commonly used for embedded IPv4 addresses.
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