[AusNOG] RFC7278 - "Extending an IPv6 /64 Prefix from a Third Generation Partnership Project (3GPP) Mobile Interface to a LAN Link"

[Karl Auer]

On Sun, 2014-07-20 at 20:22 +1000, Joseph Goldman wrote:
> To come back to this topic, in a clear opinion kind of way am I better 
> deploying a /56 or /48's per end user?

Since you appear to have a choice, /48s are the way to go. This is
giving your customers the same number of SUBNETS as they would get
ADDRESSES in an IPv4 /16, and each and every one of those subnets has
more addresses than you can possibly imagine.

By giving all your customers the same large allocation, you reduce the
likelihood of anyone coming back for more, reducing your support costs
AND giving your customers the same benefit. Having all downstream
allocations the same size also means simplicity of configuration, of
routing, of filtering, of documentation and so on. With simplicity come
lower cost of administration and better security through reduced chance
of error. You avoid the niggling feeling that you may have been giving
out too-small allocations. Oh - and you have a competitive advantage
over people who are only giving out /56s :-)

Make sure you size your RIR requests accordingly, of course. If
necessary discuss it with your RIR contact to make sure your
expectations are understood.

If there is any likelihood at all that any customers will need MORE than
a /48, go for sparse allocation. This algorithm says "satisfy any
request from the low end of the largest possible allocation remaining;
if there are two remaining spaces the same size, satisfy the request
from the low end of the lower space". Your ability to hand out large
allocations is rapidly diminished, but you maximise your chance of being
able to extend any given allocation. You can run this algorithm in a
subspace of your allocation too of course.

Regards, K.

-- 
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Karl Auer                                          tel  +61-2-64957435
kauer at into6.com.au                                 mob  +61-428-957160
                                         
Into6 - IPv6 design, support, training                www.into6.com.au

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