Re: v6 subnet size for DSL & leased line customers

On Thu, 27 Dec 2007 18:08:10 -0800
"Scott Weeks" <surfermauigateway.com> wrote:

> 
> 
> 
> 
> First, thanks everyone for the discussion.  I learned
more from this than a LOT of other discussions on IPv6.  I
now have a plan and I didn't before...
> 
> It looks to me that one really has to know his
customer's needs to plan out the allocation of IPv6 space. 
That leads me to believe that a /56 is going to work for
everyone on this network because, at this time, only very,
very few of our largest customers might possibly have a need
for more than 256 /64 subnets.  In fact, almost all
household DSL customers here only have one LAN and I could
get away with /64s for them because they wouldn't know the
difference.  But in an effort to simplify the lives of the
network folks here I am thinking of a /56 for everyone and a
/48 on request.
> 

Out of curiosity, what in form would a request for a /48
need to be? A
checkbox on the application form, or some sort of written
justification? Remember that with an initial RIR allocation
of a /32,
you've got 65K /48s ... so they're pretty cheap to give
away.

> Now I just gotta wrap my brain around 4.7x10^21
addresses for each customer.  Absolutely staggering.
> 

Ever calculated how many Ethernet nodes you can attach to a
single LAN
with 2^46 unicast addresses? That's a staggering number
too.

Regards,
Mark.

> scott
> 
> 
> 
> --- randypsg.com wrote:
> 
> From: Randy Bush <randypsg.com>
> To: Joel Jaeggli <joeljabogus.com>
> CC: nanogmerit.edu
> Subject: Re: v6 subnet size for DSL & leased line
customers
> Date: Thu, 27 Dec 2007 13:19:27 +0900
> 
> 
> >> vendors, like everyone else, will do what is
in their best interests.
> >> as i am an operator, not a vendor, that is
often not what is in my best
> >> interest, marketing literature aside.  i
believe it benefits the ops
> >> community to be honest when the two do not
seem to coincide.
> > If the ops community doesn't provide enough
addresses and a way to use
> > them then the vendors will do the same thing they
did in v4.
> 
> i presume you mean nat v6/v6.  this would be a real
mess and i don't
> think anyone is contending it is desirable.  but this
discussion is
> ostensibly operators trying to understand what is
actually appropriate
> and useful for a class of customers, i believe those of
the consumer,
> soho, and similar scale.
> 
> to summarize the positions i think i have heard
>   o one /64 subnet per device, but the proponent gave
no estimate of the
>     number of devices
>   o /48
>   o /56
>   o /64
> the latter three all assuming that the allocation would
be different if
> the site had actual need and justification.
> 
> personally, i do not see an end site needing more than
256 subnets *by
> default*, though i can certainly believe a small
minority of them need
> more and would use the escape clause.  so, if we, for
the moment, stick
> to the one /64 per subnet religion, than a /56 seems
sufficient for the
> default allocation.
> 
> personally, i have a hard time thinking that any but a
teensie minority,
> who can use the escape clause, need more than 256. 
hence, i just don't
> buy the /48 position.
> 
> personally, i agree that one subnet is likely to be
insufficient in a
> large proportion of cases.  so keeping to the /64 per
subnet religion, a
> /64 per site is insufficient for the default.
> 
> still personally, i think the one /64 subnet per device
is analogous to
> one receptacle per mains breaker, i.e. not sensible.
> 
> > there are three legs to the tripod
> > 	network operator
> > 	user
> > 	equipment manufacturer
> > They have (or should have) a mutual interest in:
> > 	Transparent and automatic configuration of
devices.
> 
> as you have seen from chris's excellent post [0] on
this one, one size
> does not fit all.  this is likely another worthwhile,
but separate,
> discussion.
> 
> > The assignment of globally routable addresses to
internet
> > connected devices
> 
> i suspect that there are folk out there who equate nat
with security.  i
> suspect we both think them misguided.
> 
> > The user having some control over what crosses the
boundry
> > between their network and the operators.
> 
> yup
> 
> randy
> 
> ---
> 
> [0] - <http://www.merit.edu/mail.archives/nanog/msg04887.html
>
> 
> 


-- 

        "Sheep are slow and tasty, and therefore must
remain constantly
         alert."
                                   - Bruce Schneier,
"Beyond Fear"

> Ever calculated how many Ethernet nodes you can attach
to a single LAN
> with 2^46 unicast addresses?

you mean operationally successfully, or just for marketing
glossies?

randy