IPv6 Address Planning

Wed Aug 10 19:39:32 UTC 2005

On 10-aug-2005, at 19:51, Daniel Senie wrote:

>> BTW, there is discussion about rethinking /48s for customers in IPv6.
>> Thoughts?

> Where is this being discussed?

All over the place. IETF IPv6 wg, RIRs...

> What sizing is being discussed?

The observation is that with the 80% HD ratio (= waste 1 bit in 5  
because of administative boundaries in the addressing hierarchy) and  
a /48 per customer we'll get awfully close to using up 128 bits  
several decades from now. (3 bits are given for the global unicast  
space, 80 for the customer = 45, 80% = 36 bits ~= 64 billion /48s for  
some 10 billion people. Not immediately problematic, but a few more  
bits margin just in case wouldn't be a bad idea.)

So we can change the HD ratio, change the /48 or change the /64. IETF  
will 99% sure veto changing /64 because it's in a lot of RFCs and  
implementations, so that leaves increasing the HD ratio or rethinking  
giving _every_ customer a /48.

> I'm expecting in the long run some ISPs will hand out /128s in the  
> hope that this will once and for all keep customers from putting  
> more than one device on a connection

That only makes sense if they can give out more /128s on demand for a  
price to make more money. But I don't see it happening anyway.

> (of course that would be followed immediately by implementations of  
> NATv6 if it happened).

Yeah right, the whole industry is going to spend man-years just  
because one ISP does something weird? (Don't underestimate the crap  
that goes on below the surface to make NAT work for stuff that isn't  
simple TCP/client-server.)

> There is a draft pending in the IETF V6OPS WG (draft-ietf-v6ops- 
> nap-01.txt) that relies heavily on the fact that everyone and his  
> dog gets a /48

A quick scan doesn't show this.