The standard Internet Protocol known as IP is
the basic standard network layer on which are based most corporate networks. This
protocol allows communication among heterogeneous networks and is responsible
for addressing and routing of packets between hosts and networks. The current
version of IP that is widely used in the internet and private networks is known
as Internet Protocol Version 4 (IPv4).
When IPv4 was first deployed, about 1,000
computers were linked to it. The developers of the protocol did not imagine
that its 32–bit address size will not be enough to cope with the current growth
rate of the internet (Andress, 2005). Even though there were some techniques
including Network Address Translation (NAT) used to extend the address size.
Unfortunately, IPv4 could still not be saved from address exhaustion problem.
Besides its address space shortage, securing data within the IP layer, Quality
of Service and mobility issues were other challenges faced in IPv4.
To tackle these limitation, the Internet
Protocol version 6 (IPv6) was developed to replace IPv4. IPv6 is an innovative
step from IPv4 but has several improvements over its predecessor. In IPv6, the
total address space is extended from 32 bits to 128 bits, providing 2128
(about 3.4 × 1038) IP addresses. This expansion means that assigning
IP address to devices on the internet can now be done with much flexibility.
IPv6 also has other features that offer many
advantages over IPv4. These are:
Quality of Service mechanisms: the header of IPv6 is designed to include QoS mechanisms. Inside
the header of IPv6 are the traffic class and the flow label fields that are
intended for traffic classification in order to provide quality of service.
With these two fields, nodes in IPv6 can distinguish certain packets so that
routers can take special care of those packets. Please refer to figure1.