I've always been at odds with the recommendation in RFC 3177 towards allocating /48 IPv6 prefixes to end-sites. To me this seemed rather short-sighted, akin to saying that 640K of memory should be enough for anybody. It's essentially equivalent to giving out /12s in the IPv4 world which in this day and age might seem completely ridiculous, but let us not forget that in the early days of IPv4 it wasn't uncommon to get a /16 or even a /8 in some cases.
Granted, I know there are quite a few more usable bits in IPv6 than there are in IPv4, but allocating huge swaths of address space simply because it's there and we haven't thought of all the myriad ways it could be used in the future just seems outright wasteful.
So you can imagine my surprise and also my elation last week when the IETF published RFC 6177 entitled 'IPv6 Address Assignment to End Sites'. In it, the general recommendation of allocating /48s to end-sites that has long been the defacto standard since the original publication of RFC 3177 in 2001 has finally been reversed.
It seems that sanity has finally prevailed and the IAB/IESG have decided to take a more pragmatic approach towards address allocation in IPv6. The recommendations in RFC 6177 attempt to balance the conservation of IPv6 addresses while at the same time continuing to make it easy for IPv6 adopters to get the address space that they require without requiring complex renumbering and dealing with other scaling inefficiencies in the long term. It is clear that acting too conservatively and allocating very small address spaces could act as a disincentive and possibly stifle widespread adoption of IPv6.
The new current recommendations for address allocations are as follows:
- /48 in the general case, except for very large subscribers
- /64 when it is known that one and only one subnet is needed by design
- /128 when it is absolutely known that one and only one device is connecting
It goes on to state other recommendations and offers guidance to operators with regards to when to allocate certain prefix lengths. But essentially, what this means is that now individual network operators have more options regarding which prefix size to allocate, and allows them to move away from strict general guidelines. In essence, operators make the decision as to what prefix size to allocate based on an analysis of the needs of particular customers.
Perhaps this practical conservation may never be needed given the trillions of address space available in IPv6, but maybe, just maybe, in the very distant future if IPv6 is still in widespread use, it could very well be due to some of these recommendations being put in place today. After all, 640K did turn out to be a rather small number didn't it?
Today, I received a very disturbing email on NANOG which was forwarded from a recipient on the Global Environment Watch (GEW) mailing list. If this is true, we all need to take steps to make an orderly and smooth transition to IPv6 as quickly as possible, lest we suffer from the harmful effects described in this email.
From: Stephen H. Inden To: Global Environment Watch (GEW) mailing list Date: Fri, 1 Apr 2011 00:19:08 +0200 Subject: IPv4 Address Exhaustion Effects on the Earth
At a ceremony held on February 3, 2011 the Internet Assigned Numbers Authority (IANA) allocated the remaining last five /8s of IPv4 address space to the Regional Internet Registries (RIRs). With this action, the free pool of available IPv4 addresses was completely depleted.
Since then, several scientists have been studying the effects of this massive IPv4 usage (now at its peak) on the Earth.
While measuring electromagnetic fields emanating from the world's largest IPv4 Tier-1 backbones, NASA scientists calculated how the IPv4 exhaustion is affecting the Earth's rotation, length of day and planet's shape.
Dr. Ron F. Stevens, of NASA's Goddard Space Flight Center, said all packet switching based communications have some effect on the Earth's rotation. It's just they are usually barely noticeable. Until now.
"Every packet affects the Earth's rotation, from a small ping to a huge multi-terabyte download. The problem with IPv4 is its variable length header and tiny address space that can cause an electromagnetic unbalance on transmission lines. The widespread adoption of Network Address Translation (NAT) on IPv4 networks is making the problem even worse, since it concentrates the electromagnetic unbalance. This problem is not noticeable with IPv6 because of its fixed header size and bigger 128 bits address space", Dr. Stevens said.
Over the past few years, Dr. Stevens has been measuring the IPv4 growing effects in changing the Earth's rotation in both length of day, as well as gravitational field. When IPv4 allocation reached its peak, last February, he found out that the length of day decreased by 2.128 microseconds. The electromagnetic unbalance is also affecting the Earth's shape -- the Earth's oblateness (flattening on the top and bulging at the Equator) is decreasing by a small amount every year because of the increasing IPv4 usage.
The researcher concluded that IPv4 usage has reached its peak and is causing harmful effects on the Earth:
"IPv4 is, indeed, harmful. Not only 32 bits for its address space has proven too small and prone to inadequate solutions like NAT, it is now clear that its electromagnetic effects on the Earth are real and measurable."
"I'm convinced that the only permanent solution is to adopt IPv6 as fast as we can", says Dr. Stevens.