RE: Towards closure on NAT traversal.

["Tony Hain" <alh-ietf@tndh.net>]

Dilkie, Lee wrote:
> A lot of NAT is deployed today for economic reasons, the cost
> of getting multiple IP addresses from an ISP is way, way more
> than the cost of getting just one address. So people/small
> companies use NAT to multiplex and lower costs. Unless the
> tariffs are changed, I see no reason to assume that NAT will go away.

The economic issues of IPv4 addresses are strictly related to the
artificial scarcity of conservation. For every public IPv4 /32 you have
today, you already have an IPv6 /48 (ie:16 bits for local subnetting -
RFC 3056). For every IPv4 NAT connected host with a private address, you
have an IPv6 /64 (ie:local use subnet for this machine, or for it to
layer-2 bridge - draft-ietf-ngtrans-shipworm). Current allocation
policies being recommended to registries for them to provide to their
ISP customers; unless you really, really know that the connecting device
is a single entity which will not further forward packets, allocate a
/48. In any case the minimum allocation to end points is a /64 (ie:
subnet).

There is no assumption that NAT will magicly go away, and there is a
specific form of NAT for translating between IPv6-only nodes and
IPv4-only ones. There is however an assumption that we should not be
wasting time designing new hacks to work around and optimize IPv4 NAT
traversal when the time would be better spent developing IPv6 products
that will have a longer lifetime.

Tony