Intro to IPv6

Anthony Borgert's Summer Project CNT 2453-01

This tutorial is aimed at developing a basic understanding of IPv6 for the new user. The reason IPv6 was created was because of an explosive increase in the number of devices requiring an IP address to communicate on a network and the depleting resources of IPv4 address space. Current estimates suggest that by 2011, all of the left over addresses will be used up; meaning anyone not already connected to the Internet risks being left behind. Born out of necessity IPv6 is a solution to this problem, made up of a suite of protocols and standards that where developed by the Internet Engineering Task Force (IETF). Not only does IPv6 increase address space but it also solves problems discovered with IPv4 that became evident over the years. Deploying IPv6 on a global scale is vital to the Internet industry.

General IPv6

The main difference between IPv4 and IPv6 is where IPv4 addresses consist of 32 bits, IPv6 addresses consist of eight blocks of 4 hexadecimal digits each. Four hexadecimal digits are equal to 16 bits, so an IPv6 address has 8*16 = 128 bits.

• An example of an IPv6 address looks like this: 2001:4CEA:8D8C:0000:0000:0000:00D2:7A4B

From this example it is apparent to anyone that IPv6 addresses are more complex to remember than IPv4 addresses. Therefore some rules have been developed to shorten addresses to something more manageable.

Address Structure Rules

Any leading digit of Zero can be dropped from any group

• The example above will look like this with this rule: 2001:4CEA:8D8C:0:0:0:D2:7A4B

Two or more groups of zeros can be replaced by two colons, (But only once per address).

• Then it looks like this: 2001:4CEA:8D8C::D2:7A4B

This is much simpler.

Types of IPv6 addresses

There are three main types of IPv4 addresses (APIPA, Private, and Public)? The same is true for IPv6, only they have different names:

• Global Address (GA): this is the equivalent of IPv4’s (public address). These addresses start with a first block in the 2000-3FFF range.

• Link-Local Address (LLA): this is the equivalent of the IPv4 (APIPA address). These addresses always start with "fe80".

• Unique Local Address (ULA): this is the equivalent of IPv4’s (private address). Where IPv4 private addresses fall within three ranges, ULA’s always start with "fd".

There are two more that have more specific uses:

• Multicast address: these addresses are reserved for multicast communications.

• Special address: these are reserved addresses for specific usage.

Some features that are available only in IPv6

• Stateless address autoconfiguration - lets hosts configure themselves automatically.

• Multicast - allows single packets to be sent to multiple destinations.

• Mandatory network layer security - integrated Internet Protocol Security (IPsec).

• Simpler router processing - Routing in IPv6 is almost identical to IPv4 routing under CIDR except that the addresses are 128- bit IPv6 addresses instead of 32-bit IPv4 addresses. With very straightforward extensions, IPv4's routing algorithms (OSPF, RIP, IDRP, ISIS, etc.) can be used to route IPv6.

• Mobility – This means that a mobile device is not constrained by location and has an “always on” IP connectivity to its home agent via a bidirectional tunnel. In other words, if there is a network that the mobile device can connect. Then it can communicate on its own home network with its own IP address, as if it was directly connected.

• Extension Header Mechanism - The extension header mechanism makes it easy to 'extend' the packet header to support future services for QoS, IPsec, Mobile IP, etc. without a redesign of the basic protocol. Extension headers do this by carrying options that are used for special packet treatment along its route or at its destination, routing, fragmenting, and for security using the IPsec framework.

• Jumbo Payload Option header – Also known as a Jumbogram allows an IPv6 packet to carry a payload larger than the standard mode size of one byte less than 64 Kilobytes.