CCNA IPv6 Overview
Notes
Chapter #1 – A History Lesson
In 1973, the Internet Protocol (IP) was part of TCPv1. In 1977, TCP and IP became separate protocols. Later in 1982, the US DoD made TCP/IP the standard for networking in the US military.
We’ve been using IPv4 for forty years, but it suffers from a limited address space (about 4.2 billion addresses, max). There weren’t enough addresses, so in the 90’s, some effort to extend IPv4 was made. NAT, CIDR, and private addresses all helped.
The ultimate solution though is IPv6.
Chapter #2 – Introducing IPv6
IPv6 addresses are 128-bits long. That’s about 340 undecillion IPv6 addresses. Unfortunately, IPv4 and IPv6 are not compatible. They can work side-by-side, but not together. So we can’t just ‘turn it on’ — we must slowly migrate to it.
One thing slowing down the adoption of IPv6 is that many applications aren’t written to support it. Another reason is that it scares some people. Even so, it’s still gaining momentum.
Chapter #3 – Exhausted!
Are we really running out of IPv4? Well, most of the public space has already been allocated by IANA and the RIRs. It’s getting harder and harder to get IP space. And reliance on the internet is growing.
So, even if it seems to be slow, yes, we really are running out of IPv4 addresses.
Chapter #4 – What’s New?
Fundamentally, there’s a lot of IPv6 that’s the same as IPv4. It’s still routable, for example.
Using IPv4 alongside IPv6 is called dual-stack, and is a common migration method.
There’s no NAT in the traditional sense in IPv6 anymore. NAT was really only there to extend the life of IPv4. There are some IPv6 NAT technologies, but they are really there to support migration to IPv6.
Older technologies have been updated to work with IPv6. These include ICMPv6, DHCPv6, DNSv6, and OSPFv3.
ARP has been retired. ARP relies on broadcast, which doesn’t exist in IPv6. Instead of broadcast, IPv6 uses multicast, which is much more efficient.