MCSA: IPV6 Subnetting Part 1

In this video and the second, IPv6 routing and subnetting are looked at. By the end of the videos you will understand how IPv6 routing works and how to use IPv6 routing and subnetting in your organization.

IPv6 Address
A single IPv6 address is 128bits in length. The address is divided into two 64bit parts. The first 64bits is the network prefix and the second is the interface identifier. In IPv4 you could apply a subnet mask to an address and thus change how many bits are used for different networks and how many bits are used for the hosts on these networks. Unlike IPv4, with an IPv6 address, the amount of bits used for networks and the amount of bits used for hosts cannot change, they are always 64bits. The advantage of this is that it makes configuring IPv6 a lot easier. You can be assured that when looking at any IPv6 address that the last 64bits are always used to identify a host on a network. The first 64bits are always used for routing and identifying networks.

Network Prefix
The network prefix in IPv6 is the value after the slash in an address. For example, 2001::23/64. IPv6 services like network discovery requires a 64bit network prefix or less. This means you should never see a network prefix greater than 64. If you are configuring a host on a network, you will always use the network prefix of 64. Different network prefixes are only used for routing. For example you may see a route like 2001::/16 on a router.

IPv6 Subnetting
A global unicast address, which is an address that is registered and thus can be routed through the public internet, has 16 bits of the address reserved for subnetting. Thus the first 48bits are used in routing on the public internet, the next 16 bits are used for subnetting inside a company.

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References
http://technet.microsoft.com/en-us/li...
http://technet.microsoft.com/en-us/li...
http://publib.boulder.ibm.com/infocen...
http://andthatsjazz.org/wbglinks/page...
http://en.wikipedia.org/wiki/IPv6_add...
http://www.clarksys.com/blog/2009/03/...
http://etherealmind.com/allocating-64...
http://www.ipv6now.com.au/primers/IPv...
http://www.apnic.net/policy/ipv6-addr...
http://software77.net/faq.html
http://tools.ietf.org/html/rfc3587

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[autohmae]

9:42 why did you use no colon, 2 colon or even 1 colon before the slash here ? a double colon is the only official way that I know of, sometimes you see no colon as well as a shorthand, but I have never seen anyone use one colon.

[itfreetraining]

Yeap, there should be 2 colon's. We will look at getting that changed.

[honfyah7]

Thanks, the explanation is very easy and clear to understand.

[itfreetraining]

Thank you very much.

[Ragrik]

Is it true that some providers gave out ipv6 addresses with subnet mask /80 . And does it mean that we can reduce the size of Host part?

[itfreetraining]

The host part I am assuming that you mean the interface identifier. This should always be 64bits. If you reduce it below 64bit this can effect other IPv6 services like network discovery. The idea behind IPv6 is that hosts on your network should always use 64 to make it simple. Different routing prefix are normally only used for routing. When you register an IPv6 address, the ISP may give you a /80 address. With /80 you have 16bits of subnet you can allocate any way you want in your company

[autohmae]

Sorry, but hierarchically dividing up global address space was an idea that did not get used.

There are 5 organizations (RIR) that give out address blocks to ISPs and other large organizations within their respective regions (North America, South America, Asia, Europe, Africa).

The ISP or organization can use the addresses anywhere in the world, they can even use one part of the address space assigned to them in one region and an other part in an other region. Or all regions at the same time.

[cablec10]

Vary nice. found the book i been needing. thanks for that. defiantly going to be using this video with the new guys.

[itfreetraining]

Glad you like the video. There is some good information on Wikipedia and Microsoft press books.

[cablec10]

This is a Vary good video for people who don't know much about IPv6 system's. any recommendations on books as well?