Introduction
In a previous article titled IP Address Basics we covered what function IP Addressing serves and many fundamentals of the IPv4 addressing scheme. There is a new protocol on the horizon, one that will eventually replace IPv4 and that is the IPv6 standard. Unfortunately, due to the growing pace of devices being added to networks across the world, there are not enough IPv4 addresses to go around. Experts recognized this in the 1990s and decided to begin working on a new protocol to replace it. We will cover the fundamental structure of IPv6 addresses and the many benefits of this new protocol but first let’s look at some basics.
IPv6 Basics
While IPv4 are 32-bits in length providing us with about 4.3 billion unique addresses , the need for a larger address space required IPv6 addresses to be longer. IPv6 addresses are 128-bits in length which provides us with approximately 340 undecillion addresses. A number that large is really difficult to grasp but here are a few ways to imagine the enormity. It provides us with more addresses than there are atoms on the surface of Earth and it is greater than the number of stars in our known Universe. Needless to say it’s a vast improvement in terms of scale over IPv4 and dare I say should provide us with enough IP addresses for the foreseeable future? Next, we examine the basic components of an IPv6 address.
45a8:67c1:08f3:90de:28bc:1280:fa87:3d46
Above you see an example IPv6 address which is structured using eight groups of four hexadecimal digits separated by colons. A hexadecimal number is represented using the characters 0-9 and A-F where A-F represent the decimal digits of 10-15. Each pair of hexadecimal digits is equal to 8 bits of data. We divide the address into two elements which are the network prefix and the device identifier. The Network prefix is the first 64-bits of the address while the device identifier is comprised of the last 64 bits of the address. Next, we will look at the types of addresses that are used in IPv6.
IPv6 Address Types
There are variety of different address types that can be used for different purposes. Below are a list of a few of them and a great reference for more is located at https://www.ripe.net/participate/member-support/lir-basics/ipv6_reference_card.pdf :
Unicast Addresses: specify a single interface and used for host-to-host communication.
Anycast Addresses: specifies a set of interfaces that all share a single address. A packet sent to an anycast address will go to the nearest host of an anycast group.
Multicast Addresses: specify a set of interfaces on many hosts. Packets sent to a multicast address will be delivered to each host of a multicast group.
Wrap Up!
In conclusion, IPv6 is the impending replacement for IPv4 addresses and provides us with many benefits. Although IPv6’s use isn’t as widespread as the IPv4 protocol it is important to understand the differences between the two. This article provides you with the foundational knowledge required to build your skills and familiarity with the IPv6 protocol.