Kofax Communication Server 9.1.1 - Manual (Page 57)

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6. IPv6 Protocol
6.1 Introduction
IPv6 protocol is the successor of the well-known IPv4 protocol which is being used in the Internet
nowadays. It was defined in December 1998 by IETF in the specification RFC 2460. The necessity for
better IP protocol is driven especially by the lack of address space provided by IPv4 addressing scheme. It
has been predicted that in around 2011-2012 the address space of IPv4 will be completely exhausted, the
large ISPs and enterprises will not get any new IPv4 addresses so they will be forced to migrate to IPv6.
6.2 IPv6 Basics
This chapter provides some basic information on IPv6 protocol, especially on its addressing syntax and
conventions, but it is not a complete IPv6 guide and does not explain how to set up an IPv6 network.
6.2.1 IPv6 Address
IPv6 protocol uses 128 bit address, as opposed to 32 bit address in the IPv4. While IPv4 addresses are
presented in the dotted-decimal form of four decimal numbers separated by period (.) character, IPv6 uses
hexadecimal representation of 16-bit boundaries (of the 128 bit address) separated by colons (:). This is
being referred to as colon hexadecimal representation.
Leading zeros in a hexadecimal group may be omitted but also several consecutive all-zero groups may be
replaced by two colons (::).
Example of three valid representations of the same IPv6 address:
2001:0db8:00a3:0000:0000:0001:2345:1234 „full format
2001:db8:a3:0:0:1:2345:1234
„suppressed leading zeros
2001:db8:a3::1:2345:1234 „suppressed consecutive all-zero groups
Each IPv6 address consists of 64-bit network part referred to as IPv6 prefix and 64-bit interface identifier.
Prefixes for IPv6 networks are expressed in the same way as Classless Inter-Domain Routing (CIDR)
notation for IPv4, which is the address/prefix-length notation.
For example, the IPv6 prefix for the IPv6 address above is:
2001:db8:a3::/64
and in the fact it stands for the contiguous IPv6 address range
2001:db8:a3:0:0:0:0:0 - 2001:db8:a3:0:ffff:ffff:ffff:ffff
With IPv6 unicast addresses (see below) the prefix length is always 64, so there is no need to write the
prefix length along with the IPv6 address. This implies that there are no masks being used with IPv6
addresses, as opposed to IPv4 masks which are necessary due to variable network/host portion of each
IPv4 address.