IPv6 Addressing, Subnets, Private Addresses

What you need to know to understand the basic addressing of IPv6 in your Windows IPv6 architecture.

ipv6 new IP

In this blog post on IPv6 addressing, subnets, private Addresses, I’m going to cover the following topics:

  • Explanation of IPv6 in terms and terminology for those of you familiar with IPv4
  • How you officially get a block of IPv6 address
  • What the equivalent of Private (internal) network addressing is in IPv6
  • Understand IPv6 addressing
  • How to subnet IPv6
  • How the concept of gateways and routing works in IPv6

This is the first of many technical blog posts I’m going to post on IPv6 architecture and implementation for a Microsoft Windows-based environment.  I started off with a basic introduction of the IPv4 problem and covered a handful of FAQs in my initial post http://www.networkworld.com/community/blog/getting-serious-ipv6-windows-networking-envir, now on to the “How to” guides…

[ Learn more from IPv6 Addressing for Enterprises. ]

Explanation of IPv6 in terms and terminology for those of you familiar with IPv4IPv6 is similar in many ways to IPv4 addressing, basically every device has to have an IP address, there is name resolution of IPv6 addresses to common names, dynamic addressing, static addressing, routing, etc.  However when drawing up the specification for IPv6, rather than doing things “exactly” like IPv4 (good and bad), IPv6 improved upon a handful of things (that I’ll explain here) to simplify addressing, routing, improve security, and improve performance and efficiency of IPv6 communications compared to IPv6.  So as much as IPv6 addresses are really long and you might assume that would put a huge increase in traffic and payload on IPv6 over IPv4, what was done “inside” IPv6 actually makes it more efficient in many ways.

So the following are terminology in IPv4 terms and how they are addressed in IPv6:

  • IP Address:  Each device will have an IP address still, but instead of an IPv4 address, it’ll have an IPv6 address.  Other than the length and slightly different look, this concept is identical
  • Subnet Mask:  We used to do subnet masks in IPv4 with notation like, but in IPv6, while we still do subnetting, the notation is different in two ways.  We now write subnets using a slash and a number that denotes the masking.  So it’ll look like IPV6ADDRESS/64 or IPV6ADDRESS/112.  But when you actually key in the IPv6 address on a system, that /64 or /112 will convert to a hexadecimal number that’ll be in the middle of the IPv6 Address.  So when you see an IPv6 address, while it is really long, it actually includes the Network Address: Subnet: Device IP Address in that long address string.  More on this in the “Understand IPv6 Addressing” section below
  • Gateway Address:  The concept of the network gateway in IPv6 is the same as in IPv4, a gateway address will be designated noting how traffic can be routed out of the current subnet (technically the IPv6 Gateway address is not a formalized standard in IPv6, however Microsoft has included a Gateway setting in their IP Configuration properties page)

So all of the concepts remain the same, but you’ll see when we get to the IPv6 addressing section that the long IPv6 address includes the Network Address, Subnet, and Unique Device Address all togheter

How you officially get a block of IPv6 address

So the next question everyone always asks is “How do I get an official IPv6 block of addresses?”  That’s kind of simple, “How’d you get your official public IPv4 addresses that you have today?”  Usually the answer is that you got them from your Internet Service Provider (ISP) such as ATT, Sprint, Comcast, or the like when you had your Internet connection line pulled into your building.  That same concept still applies as the big Internet knows generally where to find you by knowing what region you are in, and what ISP you are connected to by the general range of addressses you are using.

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