North American Network Operators Group

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Re: IPv6 Address Planning

  • From: Iljitsch van Beijnum
  • Date: Wed Aug 10 15:41:04 2005

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

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

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.