Is NAT can provide some kind of protection?

Mark Smith nanog at
Sat Jan 15 22:03:12 CST 2011

On Sat, 15 Jan 2011 18:21:52 -0600
"Frank Bulk" <frnkblk at> 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

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.

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,
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
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.


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