Supernetting and IPv6

IP version 6 (IPv6) is developed and being implemented in some areas. IPv6 will operate
alongside IPv4 and might replace it in the future. The services provided by IP, as well as the
packet header structure and contents, are specified by either IPv4 or IPv6.
The characteristics of IPv4 and IPv6 are different. Understanding these characteristics will
allow you to understand the operation of the services described by this protocol.
IP was designed as a protocol with low overhead. It provides only the functions that are
necessary to deliver a packet from a source to a destination over an interconnected system
of networks. The protocol was not designed to track and manage the flow of packets. These
functions are performed by other protocols in other layers.
Overview of IPv6
In the early 1990s, the Internet Engineering Task Force (IETF) grew concerned about the
exhaustion of the IPv4 network addresses and began to look for a replacement for this protocol.
This activity led to the development of what is now known as IPv6. This section presents
a brief introduction to IPv6.
Creating expanded addressing capabilities was the initial motivation for developing this new
protocol. Other issues were also considered during the development of IPv6, such as these:
? Improved packet handling
? Increased scalability and longevity
? Quality of service (QoS) mechanisms
? Integrated security
To provide these features, IPv6 offers the following:
? 128-bit hierarchical addressing to expand addressing capabilities
? Header format simplification to improve packet handling
? Improved support for extensions and options for increased scalability/longevity and
improved packet handling
? Flow-labeling capabilities as QoS mechanisms
? Authentication and privacy capabilities to integrate security
IPv6 is not merely a new Layer 3 protocol; it is a new protocol suite. New protocols at various
layers of the stack have been developed to support this new protocol. There is a new
messaging protocol called ICMPv6 and new routing protocols. Because of the increased
size of the IPv6 header , it also impacts the underlying network
infrastructure.
As you can see from this brief introduction, IPv6 has been designed with scalability to
allow for years of internetwork growth. However, IPv6 is being implemented slowly and in
select networks. Because of better tools, technologies, and address management in the past
few years, IPv4 is still very widely used and is likely to remain so for some time into the
future. However, IPv6 might eventually replace IPv4 as the dominant Internet protocol.
Note
ARP is a protocol of the IPv4 protocol suite. Other network layer protocols provide their own methods
of resolving Layer 3 addresses to Layer 2 addresses on a LAN. For example, in IPv6 LANs, the
Neighbor Discovery Protocol is used to translate 128-bit IPv6 addresses into 48-bit hardware
addresses.