In addition, an even more extendable and scalable version of IP, IPv6, has been de?¬?ned and
developed. An IPv6 address is a 128-bit binary value, which can be displayed as 32
hexadecimal digits. It provides 3.4 x 1038 IP addresses. This version of IP should provide
suf?¬?cient addresses for future Internet growth needs. Table 1-3 compares IPv4 and IPv6
addresses.
Table 1-3 IPv6 Addresses
Version IPv4 IPv6
Number of octets 4 octets 16 octets
Binary representation of
address
11000000.10101000.110010
01.01110001
11010001.11011100.11001001.0111
0001.11010001.11011100.11001100
1.01110001.11010001.11011100.110
01001.01110001.11010001.1101110
0.11001001.01110001
continues
Class B
25%
Class C
12.5%
Other
Classes
12.5%
Class A
50%
56 Chapter 1: Building a Simple Network
After years of planning and development, IPv6 is slowly being implemented in select
networks. Eventually, IPv6 might replace IPv4 as the dominant internetwork protocol.
Another solution to the shortage of public IP addresses is a different kind of routing. CIDR
is a new addressing scheme for the Internet that allows for more ef?¬?cient allocation of IP
addresses than the old Class A, B, and C address scheme allows.
First introduced in 1993 and later deployed in 1994, CIDR dramatically improved the
scalability and ef?¬?ciency of IPv4 in the following ways:
?– It replaced classful addressing with a more ?¬‚exible and less wasteful scheme.
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