Re: [v6ops] draft-moreiras-v6ops-rfc3849bis-00

[Mark ZZZ Smith <[e-mail]>]

----- Original Message -----
> From: Antonio M. Moreiras <[e-mail]>
> To: "George, Wes" <[e-mail]>
> Cc: "[e-mail]" <[e-mail]>
> Sent: Wednesday, 14 August 2013 11:11 AM
> Subject: Re: [v6ops] draft-moreiras-v6ops-rfc3849bis-00
> 
> On 13/08/13 16:58, George, Wes wrote:
> 
>>>  The original proposal for a larger doc prefix is all about being able 
> to
>>>  > write books and training scenarios that use a doc prefix and talk 
> about
>>>  > carving up larger chunks of address space.
> 
>>  [WEG] The thing I don't understand about that is how carving x subnet 
> blocks 
>>  out of a /32 is different from carving x blocks out of a /48 or x blocks 
> out  > of a /20 or whatever you start with as it concerns documentation.
> Other than
>>  the prefix lengths being somewhat longer, the examples of how to subnet, 
> how 
>>  to configure routing, etc still hold, don't they? AFAICT, as long as 
> you 
>>  don't end up subnetting below /64, there's really no issue. Yes, 
> real routing 
>>  policy likely won't pass a bunch of /64s, but for a lab such as what 
> you 
>>  detailed, and the subtending documentation that should work just fine, no? 
>>  Especially given that the goal is to teach someone how to do something, 
>>  instead of simply giving them something to copy with no understanding of 
>>  what it's doing.
> 
> For one of our trainings at NIC.br, each group of students have a small
> ISP with two PoPs. We try to follow the recommendations in this BCOP,
> for address planing:
> 
> http://www.ipbcop.org/wp-content/uploads/2012/02/BCOP-IPv6_Subnetting.pdf
> 
> Then, all ISPs in the lab connect to two upstreams for transit, two
> IXPs, and do private peering among themselves. We have a serie of
> exercises about traffic engineering, that depend on the address plan.
> 
> Yes, we could use /48, instead of /32 for each ISP. But doing that, we
> could not follow strictly the BCOP recommendations.

ISPs don't just get a /32, they can get larger if they need it. Placing too much value on using a /32 in your examples can strongly imply that all IPv6 addressing plans must fit within a /32.

The trouble is that if you are too prescriptive, it then creates opportunities for people to be lazy in their learning. They rote learn rather than understand, and that means they may not be able to cope with the situation is even the slightest bit different. 


I think teaching people to subnet using a range of bits should be taught first, so that they can work with a range allocations. Whether it is a /32, a /48 or a /29 then doesn't matter. Then give examples of how to apply those techniques to various sized IPv6 prefixes to re-enforce the methods.

> Yes, we could use a
> /32 from ULA space, instead of from GLA space. But we think it would
> generate confusion.
> 
> I think we are not really talking about impossibilities, but about
> options. We are talking about to write documents easier to read, labs
> easier to understand.
> 
> In some situations, for teaching, or writing scripts for labs, howtos,

> books, brochures, etc, it's better, simpler, easier, more precise, more
> clear, to use a prefix shorter than /32. In some situations we are doing
> that, and we have seen other groups doing the same.
> 
> Moreiras.

> 
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