IPv6 Explained

Rack Servers now have IPv6 Activated

IPv6, or Internet Protocol version 6, is an upgrade of Internet Protocol to increase the number of addresses available for devices connected to the internet. IPv6 uses addresses 128 bits long, compared to the 32 bit address length of its predecessor, IPv4.

IPv4 (the IP standard until the introduction of IPv6) addresses are in the familiar IP Address format, 123.456.789.012. This provides for about 4.3 billion addresses – ie. unique identifiers of devices connected to the internet – which is actually running out as of 2012. IPv6 extends this format to 1234:5678:90ab:cdef:1234:5678:90ab:cdef – so there will be around 340 undecillion addresses.

Specifically, IPv6 provides 340,282,366,920,938,463,463,374,607,431,768,211,456 IP addresses.

A large group of major internet companies along with Rack Servers upgraded their infrastructure to IPv6 as part of the Internet Society’s World IPv6 Launch Day, encouraging others to follow suit. With IPv4 addresses expected to completely run out around 2014, IPv6 is being widely implemented.

What’s different between IPv6 and IPv4?

The differences between IPv6 and IPv4 are in five major areas:

  • Addressing and routing
  • Security
  • Network address translation
  • Administrative workload
  • Support for mobile devices

IPv6 Explained:

Addressing and routing

The larger address space mentioned earlier is the main advantage of IPv6. With so many devices now connecting to the internet (like fridges ordering stock online, or home entertainment devices streaming content) IPv6 means they can each have their own unique IP address, rather than relying on the router’s Network Address Translation (see below).


Internet Protocol Security (IPSec) is built into the IPv6 protocol, and in fact was designed with IPv6 in mind. IPSec is implemented in IPv6 using:

  • AH (Authentication Header) – provides the authenticity guarantee for transported packets
  • ESP (Encapsulating Security Payload) – provides encryption of packets

Network Address Translation

Network Address Translation (NAT) was developed to cater for the limited number of IPv4 addresses by allowing many devices to share one IP address, and performing a secondary private addressing to those devices – a workaround which breaks protocols reliant on incoming connections and which carry IP addresses inside them. IPv6 renders NAT unnecessary by providing each device with a unique IP address, saving the router from having to identify each device at the router level.


IPv6′s Administrative Workload

The IPv6 packet header and packet forwarding processes have been simplified to make processing by routers more efficient. Also IPv6 routers don’t perform fragmentation – IPv6 hosts are required to either perform path MTU discovery, perform end-to-end fragmentation, or to send packets no larger than the default minimum MTU size of 1280 octets. IPv6 also removes the header checksum, assuming integrity checking done by link-layer and higher-layer error detection. Routers no longer need to recompute the checksum when the header fields change.

The use of extension headers in the IPv6 header structure expediates processing by keeping rarely-used information optional. The extension headers also allow make IPv6 extensible for possible future uses or services.

Support for mobile devices

Mobile IPv6 enables mobile devices to maintain their IP connectivity as they move across networks, changing their point-of-attachment to the IPv6 Internet without changing their IP address through the use of auto-configuration, neighbour discovery and route optimization.

IPv6 also includes an important feature: a set of possible migration and transition plans from IPv4. Due to the changes in protocol, IPv6 is not backwards-compatible with IPv4. Companies upgrading often run a dual-stack (or side-by-side) implementation to cater for both IPv4 and IPv6 protocols. Transition mechanisms have also been developed to cater for IPv6 systems to run on IPv4 networks (or vice versa). A common mechanism is the use of tunneling, which encapsulates one protocol in the other.

IPv6, although having been around since 1999, is being increasingly implemented in 2012 due to the shortage of IPv4 addresses presenting itself as a reality. By 2016, up to 8 billion devices IPv6 devices are predicted – that’s already more than the 4.3 billion addresses available with IPv4!

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About Robin Jennings

I'm a creative web designer that specialises in designing and marketing websites for small business owners, community groups and creative types. I'm based in regional Victoria but work with clients Australia-Wide as well as a healthy sprinkling of overseas clients through my Web Design Agency: Explainafide

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