Addressing plan exercise for our IPv6 course

Marco Hogewoning marcoh at
Wed Jul 21 13:47:18 CDT 2010

On 21 jul 2010, at 19:22, Simon Perreault wrote:

> On 2010-07-21 12:57, Alex Band wrote:
>> We've been working on an exercise for the IPv6 training course we deliver for LIRs. It's aimed at people who are unfamiliar with IPv6, so the goal is to get them to the point where once they get their IPv6 /32 allocation, they have a good idea how to subdivide prefixes over their network and how to write an addressing plan.
>> Here's a PDF with the exercise (two pages A3):
>> I'm curious to hear if you think it's clear and useful.
> Useful, yes. But it should be clearer that not all address plans are
> equally good. It's not just a matter of filling in the blanks with
> something that will work.

Every address plan will turn out to be a custom job anyway. Primary goal of this exercise is to show the basics and to show how you can get a lot of aggregation done without wasting a lot of space. Making people familiar with the way subnets are split up and the very basics of counting to 16.

I'm also working on a more extensive half day workshop which contains a lot more scenarios and for instance show how to fit this same network into a /48 PI assignment instead of the /32 PA. If you are bored with this one already, go ahead and try :)

> For instance, would one be expected to follow RFC 3531?

For a novice ? I wouldn't recommend it. From what I get back 'in the field' it's already hard enough to get people familliar to the whole concept of hexadecimal without going into bit level. But then again, if you are a fairly technical company maybe you can get away with it.

As far as customer assignments is concerned, I would simply stick to the /48 and not make any reservation for future growth beyond that, i should probably cater for 99% of your cases and if they really run out I can probably handle a second assignment/route for another one (or leave them the choice to renumber into a /47). In fact part of this exercise is meant to teach people how to avoid such disasters as running 'out of space' by being really inefficient.

The only way where I see this becoming relevant is when trying to make subassignments from a /48. But as far as PI is concerned, and that would be the most likely case, in RIPE region you are not allowed to make subassignments from within a PI block. The other one would be subassignments from a PA block, which under the same policy can easily be made a few bits bigger and if I would encounter a customer who would actually subassign large numbers of customers from within a PA assignment. I would recommend becoming an LIR themselves and get a /32.


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