What is IPv6, what are its Conventions, Features and Advantages

What is IPv6 and what was the need for its introduction?

IPv6 is a new IP addressing scheme. It is set to replace the IPv4 IP addressing scheme that is currently in place. You should be familiar with 169.254.0.16 type of IP address which is essentially an IPv4 structure for an IP address with 32 bits (four sections of eight bits). The primary reason to bring in a new addressing scheme is because there is expected to be a shortage of the public IP addresses that is given to companies, web hosts and also individuals. While the current IPv4 address schemes can provide 17 million useful addresses (approximately), the new IPv6 format is expected to provide at least 18 trillion useful addresses.

A basic IPv6 address, its composition and its conventions:

IPv6 addresses are 128 bit long and they are split in to 8 groups, each 16 bits long.

Example: 2001:0816:71A4:D8DD:BA1F:03AB:7081

Two things that strike immediately are – They use colon instead of the dot used earlier and they support hexa-decimal number system. So, along with numbers, letters like A,B,C,D,E,F are also present in the IPv6 addresses.   

Composition: The IPv6 address can be divided into sections. The first part has the routing information, while the middle parts hold the site identifier and subnetting information, and the last part of the address is the interface ID which is the 48 bit MAC address (physical address) of the host and the 16 bit global identifier.

Some Conventions for IPv6 addressing:

¤ Private addresses won’t need to assign the full range – So, instead of FD01:0000:0000:0000:0000:0000:0000:0004 , just a FD01::4 is sufficient. Notice the double colon.
¤ You can use the double colon only once in an IPv6 address.
¤ FD01::/8 is an address range.
¤ 2001:0898:85DF:0JPF::/64 is a subnet.
¤ 2001:0618::/32 is a route prefix.
¤ 0:0:0:0:0:0:0:1 is a loop back address (::1 is the short form).
¤ 0:0:0:0:0:0:10.0.0.20 is an IPv4 to IPv6 address (:::10.0.0.20 is the short form).
¤ Addresses beginning with FEC0 are only allowed connections with neighbours on that subnets. They are not forwarded by routers. They are called Link Local addresses.
¤ Addresses beginning with FE80 are called Site Local addresses and are routable to any other Site Local address within the organization, but not to the internet.
¤ The IPv6 addresses are not case sensitive.

Some Features of IPv6 addresses:

¤ IPv6 stack can obtain information about other hosts so that it won’t duplicate their IP address, if it needs to use auto-configuration.
¤ IPv4 addresses cannot be represented as such in IPv6. A feature called Teredo has been included by the IPv6 committee for tunneling IPv4 inside IPv6.
¤ DHCP servers should support DHCPv6 to assign IPv6 addresses.
¤ In IPv6, only the sending host fragments the packets. Routers do not, unlike IPv4.
¤ IPv6 supports multicasting – The ability to send a single packet to multiple destinations and it is a part of the base specification of IPv6.
¤ Unlike IPv4 addresses, which were distributed on a first-come-first-serve basis, IPv6 addresses are expected to be distributed by regional internet registries and that enables the possibility to have a particular range of IP addresses specific to a continent or a country, for example.

Advantages of IPv6 addresses:

These advantages are when compared to IPv4 addressing.

¤ Security: IPSec encryption is built in to IPv6 (This was optional in IPv4).
¤ Speed: An IPv6 addressing scheme is faster than IPv4 because:
IPv6 does not fragment the packets as IPv4 does.
As IPv6 is hierarchical, internet routers will not need such large routing tables.
IPv6 headers have been re-designed to speed their path through a router.
¤ Scalability: IPv6 addresses are highly scalable, when compared to IPv4.
¤ Quality of Service (QOS): IPv6 has an improved ability to prioritize packets as QOS instructions are built in to the IPv6 packet header. Also, even if the packet body is encrypted, QOS would still be functional as the header is not encrypted. This is very useful in prioritizing packets carrying real time applications like video or audio, for example.
¤ Support for Mobile phone networks: It has in-built features to support mobile networks. Eg. Mobile Node (MN) is identified by its home address (HoA) ad its Care Of address (CoA), which is the mobiles current location.

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