IPv6

IPv4

IPv4 has been around since the early 1980s. This type of internet layer protocol addressing system is made up of two parts, the network identifier and the host identifier. Using classful networking, the IPv4 addressing range was divided in 5 classes. The first 3 classes had different capacity to be used for different purposes. Class D and class E were the same size, with the former being used for multicast addressing and the latter reserved for future applications. However, at around 1985, another method was devised to divide IP networks better and variably, called Variable Length Subnet Mask. This allowed networks to be divided in a small portion for the hosts, which still allowed growth.

Figure 1: Cisco CRS-3, with100Gbps Ethernet interface and 322 Tbps of interconnect capability

IPv4 Address Depletion

The Internet Assigned Numbers Authority (IANA) is in charge of the IP address structure. Since the 1980s, it was immediately apparent that the pool of available IPv4 addresses was being depleted at a much larger rate than was initially anticipated. Classful networks, Classless Inter-Domain Routing and NAT all were created to solve the problem of IPv4 address exhaustion. However, with all these technologies, something still had to be done and in 1996, IPv6 was born.

Figure 2: Difference between the IPv4 and IPv6 header

IPv6

While IPv4 uses 32 bit addressing, IPv6 uses 128 bits. This means that there are 3.4 x 10³⁸ address. Each living person can have 4.8x10²⁸ addresses for himself. Each subnet in IPv6 has 2⁶⁴ addresses. This means that each subnet has the square size of the whole IPv4 addressing. Of course, this means that a very small number of addresses will be used in each subnet but this will help hierarchical route aggregation.

Security

IPv6 has IPSec built in its architecture. This means that IPv6 was built with security in mind. Although IPSec was engineered for IPv6, it is very common in IPv4 networks. This happened because IPSec was back-engineered to work with IPv4. IPSec was designed to be an integral part of the IPv6 protocol suite, but was later removed and made optional.

IPv6 Address Format

The IPv6 address size is 128 bits. The preferred IPv6 address representation is: xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx where each x is a hexadecimal digit representing 4 bits. IPv6 addresses range from 0000:0000:0000:0000:0000:0000:0000:0000 to ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff.

In addition to this preferred format, IPv6 addresses may be specified in two other shortened formats:

Omit leading zeros - Specify IPv6 addresses by omitting leading zeros. For example, IPv6 address 1050:0000:0000:0000:0005:0600:300c:326b may be written as1050:0:0:0:5:600:300c:326b.

Double colon  - Specify IPv6 addresses by using double colons (::) in place of a series of zeros. For example, IPv6 address ff06:0:0:0:0:0:0:c3 may be written as ff06::c3. Double colons may be used only once in an IP address.

An alternative format for IPv6 addresses combines the colon and dotted notation, so the IPv4 address may be embedded in the IPv6 address. Hexadecimal values are specified for the left-most 96 bits, and decimal values are specified for the right-most 32 bits indicating the embedded IPv4 address. This format ensures compatibility between IPv6 nodes and IPv4 nodes when you are working in a mixed network environment.

These two types of IPv6 addresses use this alternative format:

IPv4–mapped IPv6 address - This type of address is used to represent IPv4 nodes as IPv6 addresses. It allows IPv6 applications to communicate directly with IPv4 applications. For example,0:0:0:0:0:ffff:192.1.56.10 and ::ffff:192.1.56.10/96 (shortened format).

IPv4–compatible IPv6 address - This type of address is used for tunneling. It allows IPv6 nodes to communicate across an IPv4 infrastructure. For example, 0:0:0:0:0:0:192.1.56.10 and::192.1.56.10/96 (shortened format).

All of these formats are valid IPv6 address formats.

IPv6 Day - 6th June, 2012

Instead of swapping an ISP one by one to change from IPv4 to IPv6, a day was organized so that a bulk change will be done. http://www.worldipv6launch.org/measurements/ shows the statistics and changes  which happened in the area of IPv6 since 6th June, nearly a month later.

Figure 3: Banner for World IPv6 Launch