Re: Deploying IPv6 in an ISP network [ was: Best Source for ARIN Region /24 ]

[Owen DeLong <owen () delong com>]

> On Jan 11, 2016, at 16:21 , Hugo Slabbert <hugo () slabnet com> wrote:
>
> On Mon 2016-Jan-11 20:16:21 +0000, Shon Elliott <selliott () getunwired com> wrote:
>
> > I also am interested in where people are finding blocks of /22 or smaller just in case. We have some blocks from 
> > Level 3, but eventually, we're going to be out.
> >
> > That being said, we did get our IPv6 /32 allocation from ARIN. If anyone has any ideas on how to properly deploy 
> > this in an ISP environment, I'd love to learn. I've read some whitepapers on the subject, but most of those deal 
> > with enterprise based networks, and not so much as a service provider.

Step 1: Figure out what size block you should have requested and go back and get that.

Sure, that’s a little bit flip, but I’m actually serious. Most ISPs will need more than a /32 unless they are fairly 
trivial.

Instead of starting from a /32 and figuring out how to squeeze your customers into it, you should start from the number 
of end-sites you expect to serve from your largest serving site (POP or other aggregation point in your network) in the 
next, say 5 years.

Round that up to a nibble boundary with 25% free.

For example, if your largest site has fewer than 192 end-sites served, 8 bits is enough. If you have 192 or more but 
less than 3072, 12 bits is enough.
IF you have a million customers in your largest serving site, you’re looking at 20 bits or more per serving site.

Next, figure out the number of serving sites you expect to have in the next 5 years and round that up to a nibble 
boundary (again with 25% free).

So, if you expect to have more than 12, but fewer than 192 serving sites, 8 bits is enough. Fewer than 12, you can get 
by with 4 bits. From 192-3071, 12 bits.

Now, add those two sets of bits together and subtract from 48.

That’s your prefix size that you need to ask for.

I’m quite certain you can get that size prefix if you’ve done the exercise correctly because that’s exactly how the 
policy is written.

Owen