[arin-discuss] Trying to Understand IPV6

[michael.dillon at bt.com]

> If I assigned a customer say an IPV4 /21 in IPV6 this would translate
> into a /56? If I'm not mistaken a /56 would translate into something
> like 65,000 host addresses? That just seems like a lot of hosts to me,

Anyone in this position should simply assign a /48 to every customer site
no matter how big or small. A one bedroom apartment gets a /48. A manufacturing
plant with 5 buildings including a 4-story office block, gets a /48. 
No exceptions.

Later, when you have learned more, you might want to shift to only give
a /56 to residential customers if there is a good business reason, but
you are more likely to conclude that there is only a reason for large
ISPs to introduce this complexity.

> especially when most of the time I'm working with networks that are /26
> or smaller. I guess my big problem is confusion over labeling. What
> would be the equivalent of a /26, /27, /28 or have we done away with
> blocks that small and simply would just assign a /56 instead?

The equivalent to everything that you mentioned is /48.
Only use /56 for private residence customers and even that is
optional and probably a bad idea when doing forecasting.

ARIN has a wiki at http://www.getipv6.info with some good basic info and
links to lots of tutorials on other sites. Spend some time there.

--Michael Dillon