RE: Dual stack IPv6 for IPv4 depletion

["Naslund, Steve" <SNaslund () medline com>]

It seems like there might be several incorrect assumptions here leading to over thinking the issue.

        1.  Over a long period of time, will the size or number of subnets be significantly different than today.  Even 
today a bunch of our assumptions on why subnets are created the way they are might be obsolete or close to it.  For 
example, broadcast domain size becomes less of an issue as broadcasts are used less (presumably by better targeted 
multicast and smarter protocols) and device performance increases.  Maybe networks get smart enough to reorganize 
themselves and their subnets to optimize performance or maybe there will not be the need to do so.

        2.  Am I wrong or are we making some bad assumptions about "routability" of subnets?  It seems like we might be 
too concerned about the minimum routable sized subnet when in reality that is just a policy decision open to change 
over time.  Also, the routing I do inside my home does not need to be routable to the Internet at large.  Summarization 
can occur in my home and at the service provider level.

        3.  If a couple of users required an inordinate amount of subnets, why not assign them an additional netblock?  
In the V4 world Fortune 500 global networks are not treated the same as your grandma's cell phone.  It's nice to have 
the comfort of doing it with V6 but no real compelling reason not to have more than one type of customer assignment.  
Why not size things for the usual use case and add another allocation as needed?  Seems really wasteful to do anything 
else.  The NICs don't give a global carriers the same assignments they give a simple dual homed user why should you 
think all of your sub-assignments would be identical?

        4.  This is not the last time in history that you might get to reorganize your address space so don't try to 
plan for crazy edge cases.  Given the widespread use of DHCP (or any other automatic addressing technology) in the V6 
world it is archaic to think that an address change will be a big inconvenience.  If my device receives an address and 
auto updates DNS records then I really do not care what that address is.  Feel free to reorganize the network whenever 
you want.

        5.  The car example does not work because I am assuming you don't drive in your home.  You probably roam all 
around the area and will be getting dynamic assignments from whomever the provider is.  Do you statically address your 
iPhone when it is on the 3G/4G/LTE network?

Steven Naslund
Chicago IL

> > > Subject: Re: Dual stack IPv6 for IPv4 depletion

> > > On 9 July 2015 at 11:42, Matthew Huff <mhuff () ox com<mailto:mhuff () ox com>> wrote:
> > > What am I missing? Is it just the splitting on the sextet boundary that is an issue, or do people think people 
> > > really need 64k subnets per household?

> > > One thing you're missing is that some of these new-fangled uses for IP networking will want to do their own 
> > > subnetting. It's not "here's a subnet for the car", it's "here's a /56 for the car to break into smaller pieces as 
> > > > > > required".

> > A /56 isn't 256 subnets, it's 8 levels of subnetting (or 2 levels, if you're human and want to subnet at nibble 
> > boundaries). A /48 is 16 (or 4) levels. I have four vehicles, so I'd want to carve out a /52 for "the car network" to 
> > > > make the routing and security easier to manage, and leave room for expansion (or for my guests...)

> > One more consideration for you: we're currently allocating all IPv6 addresses out of 2000::/3. That's 1/8th of the 
> > space available. If we discover we've messed up with this sparse address allocation idea, we have 7/8ths of the 
> > > > remaining space left to do something different.