moving to IPv6

Sean M. Doran smd at
Sat Nov 1 19:34:00 UTC 1997

Phil Howard <phil at> writes:

> IPv4 space is not enough for dedicating 1 IP address to
> every person.


IP space is not enough for dedicating 1 IP address
with global scope permanently to every person.

Remember: CIDR requires renumbering, which means that the
permanence is no longer the case; this substantially added to the
lifetime expectancy of IP.  NAT translates at NAT borders
which means addresses have local scope.  This even more
substantially adds to the lifetime expectancy of IP.

NAT also mitigates the cost of renumbering to comply with CIDR. 

Note that with aa decent evolution towards describing
services as a domain name and a service name that is
relative to the domain name, then the IPv4 address space
is essentially extended proportional to the number of
autonomous NAT domains and within each such domain
proportional to the number of useable ports to which the
service names may map.

> There are also increased costs involved in the processes being used to
> manage allocations of IPv4 space.  

Allocations are local.  ARIN/RIPE/APNIC allocate within
one large NAT domain, and not within other NAT domains.
As NAT continues being deployed, and in particular if very
large scale NAT (e.g., between ISPs) becomes workable and
efficient, then it is local registries and not
ARIN/RIPE/APNIC that will be managing allocations of local
IP addresses, and NATs managing translations at NAT domain borders.

> With IPv4 space being managed better with CIDR, we do have more time to
> find the right way to deploy IPv6.

No, with IPv4 space being managed better with CIDR we have
had time to develop and deploy NAT on a continually
growing scale, and have had the time to reflect that this
scales better than a migration to IPv6.  What is not
completely clear is that IPv4ever is the best approach,
but what is completely clear is that NAT and the IPv6 work
on protocol translation means that a better protocol than
IPv6 can easily be deployed locally within a NAT/protocol
translation domain.

> Whether to IPv6 or not, maybe we should be looking at what next for BGP4.

A chainsaw right through it.


More information about the NANOG mailing list