IPv6 Resolves IPv4 Issues

With the growth of the Internet and its possible extension to additional

devices, such as TVs, toasters, and coffee makers, all IPv4 solutions pro 

posed for scaling the Internet address space will only delay the

inevitable. There are just not enough IPv4 addresses. The IETF has pro 

duced a comprehensive set of specifications to define what is commonly

known as the next generation IP protocol ( IPng  or  IPv6 ). IPv6

eliminates the need for VLSM, CIDR, and much more. 

Introduction to IPv6 Addressing

IPv6 increases the IP address size from 32 bits to 128 bits to support

more levels of the addressing hierarchy, a much greater number of

addressable nodes, and simpler auto configuration. IPv6 supports

approximately 340,282,366,920,938,463,463,374,607,431,768,211,456

possible IP addresses. IPv6 text representation is very different from

IPv4. The address form can be written three ways (preferred, com 

pressed, and mixed) and it offers three different types of addresses (uni 

cast, anycast, and multicast).

The preferred form is the full IPv6 address in hexadecimal values which

is X:X:X:X:X:X:X:X, where each X refers to a four digit hexadecimal inte 

ger (16 bits). Each digit consists of four bits, each integer consists of

four digits, and each address consists of eight integers which totals 128

bits (4 x 4 x 8 = 128). A colon must be included to separate each inte 

ger. Note that the integers are hexadecimal integers and the letters A

through F represent the numbers 10 through 15. Figure 36 depicts a full

hexadecimal to binary IPv6 address. 

F I G U R E   3 6 .   H e x i d e c i m a l   t o   B i n a r y   C o n v e r s i o n

The compressed form substitutes zero strings with double colons (::) to

compress the zeros. This method replaces zeros only when they fill a

complete 16 bit group, and the double colon can be used only once in

any given address. The double colon can also be used to compress the

leading or trailing zeros in an address. For example address

1080:0:0:0:8:800:200C:417A could be represented as

1080::8:800:200C:417A. In addition to replacing the zeros that complete

a 16 bit group, all zeroes that are to the left of a given 16 bit expression

may be left out. Table 4 shows the compressed form of some IPv6

addresses using the double colon. 

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