Take a chance on the changes: IPv6 Demystified Part 1

James Hanback. There may come a point in your career where the basic networking tasks that you can do in your sleep, such as subnetting an IPv4 network (IPv4), will become obsolete. You were warned. We were all warned. Even though IPv4 addressing has become far too common to move anywhere soon, and although the deployment of IPv6 (IPv6) was slow, it is expected that more widespread deployments of IPv6 will occur. The ability to understand, and implement IPv6 addressing is now a topic on network certification exams such as the Cisco Certified Network Associate exam (CCNA), which focuses on the ability to understand, and implement IPv4 addressing.
IPv6 awareness and deployment is increasing every year. Who is to say you won’t be confronted one day with the daunting task of migrating your company’s network from IPv4 to IPv6? You read that correctly. There might come a day when the octet.octet.octet.octet finger memory you’ve built up over your many years as a network admin will no longer serve you, and your younger peers will automatically associate a /32 subnet not with a single-host IPv4 subnet but with the approximately 4.3 billion subnets of 264 addresses each that are created by using an IPv6 /32 prefix.
Have you reached under your desk yet No? Good. Because you still have plenty to learn. You still have time to learn, even if you’re not being assigned with the chore.
The Inevitable Contrasting between IPv6 and IPv4
Nearly every guide to IPv6 begins with a comparison of IPv6 and IPv4. This is most likely because you are already familiar in some way with IPv4 through previous experience or study. It is important to recognize that there are significant differences between the standards. If you don’t pay attention, your IPv4 knowledge could cause your IPv6 learning process to be slowed down (remember the slash notation example in a few paragraphs). The purpose of the contrast between IPv6 and IPv4 is to help you remember the “fresh start” idea so that you don’t assume that everything works the same way in IPv6. Here’s a handy contrast table that highlights some key differences between IPv6 & IPv4.

IPv4
IPv6
32-bit address space
128-bit address space
232 unique addresses
2128 unique addresses
Uses dotted-decimal notation. Example:
198.51.100.5
Uses the hexadecimal system. Example:
2001:1234:5678:90AB:CDEF:0000:0000:0001
Subnet ranges are represented using either dotted-decimal subnet masks, or slash notation Prefixes
Only slash prefixes can be used to represent the subnet range
Broadcast addresses supported
Anycast addresses supported
RFC 1918 is used for private networks
RFC 4193 is used for private networks
Can support, but not require, the automatic configuration link-local addresses
Requires every IPv6 network device to automatically configure a link local address
Can be configured for IP Security (IPSec).
Natively supports IPSec
1982 was the first year that standardization was made
First standardization in 1999
Most of the Internet is available.
The majority of the Internet is not connected to it.

Simmer down, now. The last one was a joke. Despite the fact that the table above is a joke, it’s easy to see why network administrators who have worked in IPv4 for most of their careers would be reluctant to migrate to IPv6, especially considering the availability of IPv4 longevity enhancing technologies, such RFC 1918, as well as IPv4 protocols, such as Network Address Translations (NAT) or Port Address Translations (PAT).
Although it is simple to scale a 32-bit address area up to a 128 bit address space, this is not the only difference between the standards. You cannot use math to convert your IPv4 dotted decimal network to a Hexadecimal value. There are many other things you can do.