IPV six was developed by the Internet Engineering Task Force IETF.
I'm sure you looked it up to deal with the long anticipated problem of IPv4 address exhaustion.
So IPV six is intended to replace IPV four.
IPv6 became a draft standard in December 1998 and became an Internet standard on the 14th of July 2017.
So instead of 32 bit addressing of IPV four, which provides approximately 4.3 billion addresses, IPV
six uses a 128 bit address.
So that theoretically gives us two to the power of 128 or approximately 3.4 times ten to the 38th addresses.
Big number.
You can check my math later, but stick with me for now.
I mean, the actual number is slightly smaller as multiple ranges are reserved for special use or they're
just completely excluded from use.
But with a rough calculation, the total number of possible IPV six addresses is more than 7.9 times
ten to the power of 28 times as many as IPV four.
The two protocols IPV four and IPV six are not designed to be interoperable.
Complicating the transition to IPv6, however, several IPv6 transition mechanisms have been devised
to permit communication between IPV four and IPV six hosts.
In addition to offering more addresses, IPV six also implements features not present in IPV four.
Simplified header.
IPv6 header has been simplified by moving all unnecessary information and options which are present
in the IPv4 header to the end of the IPv6 header.
The IPv6 header is only twice as big as an IPV four header because that IPV six address is four times
longer.
End to end connectivity.
Every system now has a unique IP address and can traverse through the internet without using Nat or
other translating components.
After IPV six is fully implemented, every host can directly reach other hosts on the internet with
well with some limitations involved, like a firewall organization, policies and stuff like that.
Autoconfiguration.
IPV six supports both stateful and stateless autoconfiguration mode of its host devices.
This way the absence of a Dhcp server does not put a halt on inter-segment communication.
Faster forwarding and routing.
A simplified header puts all unnecessary information at the end of the header like we saw earlier.
The information contained in the first part of the header is adequate for a router to make its routing
decisions, thus making them as quickly as looking at the mandatory header.
IPsec.
Initially it was decided that IPV six must have IPsec making it more secure than IPV four.
This feature has now been made optional.
IPsec Internet Protocol security is a framework of open standards for helping to ensure private, secure
communications over Internet protocol networks.
IP networks through the use of cryptographic security services.
IPsec is an end to end security scheme operating in the network layer, while some other internet security
systems in widespread use, TLS and SSH operate in the upper layers.
IPsec can automatically secure applications at the IP layer.
No broadcast.
Though Ethernet and token ring are considered a broadcast network because they support broadcasting.
IPV six does not have broadcast support anymore.
It uses multicast to communicate with multiple hosts.
Mobility.
IPV six was designed keeping mobility in mind.
This feature enables hosts such as a mobile phone to roam around in different geographical areas and
remain connected with the same IP address.
The mobility feature of IPV six takes advantage of auto IP configuration and extension headers.
Extensibility.
One of the major advantages of the IPv6 header is that it is extensible, adding more information in
the option part.
IPV four provides only 40 bytes for options, whereas options in IPV six can be as much as the size
of the IPV six packet itself.
What is the IPV six packet you ask?
You came to the right place.
An IPV six packet is the smallest message entity exchanged via the internet protocol across an IPV six
network.
But stay with me here.
The packets consist of control information for addressing and routing and a payload consisting of user
data.
The control information in IPv6 packets is subdivided in a mandatory fixed header and optional extension
headers.
The fixed header starts an IPV six packet and has a size of 40 octets, which means 320 bits.
Its format is shown in the slide.
Version is constant.
Six.
Payload length is the size of the payload in bytes, including any extension headers.
Hop limit replaces the time to live field in the IPV four.
Well, I think source address and destination address fields are fairly obvious.
Extension headers carry optional internet layer information and are placed between the fixed header
and the upper layer protocol header.
128 bit.
IPV six addresses are written using hexadecimal as opposed to dotted decimal.
Back in IPV four.
Because a hexadecimal number uses four bits.
This means that an IPV six address consists of 32 hexadecimal numbers.
These numbers are grouped in fours, giving eight groups or blocks.
The groups are written with a colon as a separator.
An IPV six address example is shown in the slide.
So because of the length of the IPV six addresses, various shortening techniques are employed.
The main technique being to omit repetitive zeros as shown in the example.
So as I mentioned before, in IPV four, an address is split into two components.
Right?
Network ID and a host ID.
This was done initially using address classes and then later using subnet masking.
In the unicast addressing of IPV six.
It's done in the same way.
The first step is to split the address into two parts.
The address is split into 264 bit segments.
The top 64 bits is a network ID and the lower 64 bits is the host ID.
The most significant 64 bits are used for routing and the least significant 64 bits.
Identify the address of the interface or host.
This block is derived from the actual physical or Mac address.
In practice.
So if we look at the most significant 64 bits in more detail, we can see that it's split into two blocks
of 48 and 16 bits.
Now the least significant 16 bits are used for subnets on internal networks and are controlled by a
network administrator.
The most significant 48 bits are used for the global network addresses and are used for routing over
the Internet.