The Choice: IPv4 Exhaustion or Transition to IPv6

Justin M. Streiner streiner at
Thu Jun 28 16:28:56 UTC 2007

On Thu, 28 Jun 2007, Stephen Wilcox wrote:

> First is the belief that the Internet will suddenly break on the day 
> when the last IP block is allocated by an RIR - the fact that most of 
> the v4 space is currently not being announced may mean we have many 
> years before there are real widespread shortages

Widespread?  No.  Pockets of problems?  Yes.

A large corporation or .edu that got n x /16s or even a /8 of v4 space in 
som cases and is only using a small fraction of that has no motivation 
based on address exhaustion to migrate to v6.  ISPs and other 
organizations that regularly 'go back to the well' for more address space 
are in a different boat.  They want to be ready with a plan well in 
advance of the day they'd go back to the well again and have have $RIR 
tell them there are no more blocks to assign.

> Second is the belief that this will prompt a migration to IPv6, as 
> though moving to an entirely different and largely unsupported protocol 
> stack is the logical thing to happen. Surely it is easier and far 
> cheaper by use of existing technology for example for organisations to 
> make efficient use of their public IPs and deploy NATs?

Large-scale NATs introduce their own large-scale problems.  Many modern 
OSes include v6 stacks already, but it needs to be enabled in a lot lf 
those cases.  Where you'll run into problems are either older machines or 
hardware devices with built-in IP stacks.  Running a dual-stack backbone 
can ease some of those transitional headaches.

> As technology people we are looking at v6 as the clean bright future of 
> IP, but the real world is driven by economics and I dont see v6 as being 
> economically viable in the near future....

That will change over time.  Last I heard, the US government is in the 
midst of a big push to v6.  I wouldn't be at all surprised to see some 
federal grants come with riders requiring v6 connectivity in the 
not-too-distant future.  That will get the attention of the large .edus 
with legacy v4 assignments and the businesses that have federal research 
grant funding as a significant part of their cash flow.


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