Re: Is NAT can provide some kind of protection?

[Owen DeLong <owen () delong com>]

On Jan 15, 2011, at 8:03 PM, Mark Smith wrote:

> On Sat, 15 Jan 2011 18:21:52 -0600
> "Frank Bulk" <frnkblk () iname com> wrote:
>
> > I hope the engineers in the organization will just tell their marketing folk
> > that it's not possible to hand out just one IPv6 address.  "Our hardware
> > doesn't support it."
> >
> > I think there's still room for ISPs to charge $10/month for a static prefix,
> > though.  And that's technically possible.
>
> I think it is important to define what "static" means. My definition is
> that no matter where the customer's network attachment point moves to,
> the customer retains the same addressing while they have a continued
> commercial relationship with the SP - in effect PI address space within
> the SPs network. There is a fairly significant cost to preserving that,
> a guaranteed route table slot. This is typically a business product
> offering.
Uh, yeah, I think most SPs will only provide that as long as the customer
is attached at the same POP or possibly in the same Region, whatever
their aggregation zone happens to be.

If you're going to have the customer tying up a slot in the routing table,
there's not much benefit (from an SP perspective) vs. having them go
get an AS and a PI Prefix.

> The only other alternative people seem to think there is is dynamic,
> where every time the customer reconnects they may get different
> addressing. This is the typical residential product offering.
Well, there's static as long as the customer stays where they are or
moves within the same access aggregation facility. That's relatively
easy for the provider and solves 99.99% of the residential customer's
problems with dynamic.

> I think there is a useful middle point of "stable" addressing, where as
> long as their point of attachment (or point of service delivery - i.e.
> their home) doesn't change, a customer would continue to get the
> same addressing. This idea wasn't as useful or as applicable in IPv4,

Frankly, that's what I thought you meant by "static" at first.

> but would be quite beneficial in IPv6 when DHPCv6-PD is being used. It
> wouldn't be an assured address assignment, however the SP would
> endeavour to try to ensure the addressing stays stable over quite long
> periods of time. It's common enough for LNS/BRASes to do this anyway if

Hmmm... Now your going away from your definition of "stable" to what I
would call "semi-sticky dynamic addressing". It's a darker shade of gray
than "stable", but, still reasonably usable.

> the customer's connection lands on the same one. The trick is to expand
> this stability over the group of all LNS/BRASes that customers can
> attach to when they reconnect, such that is a SP designed behaviour,
> rather than an implementation behaviour of each individual LNS/BRAS.
You're making a rather large assumption here. Namely that all the world
is DSL.

Owen