[address-policy-wg] Re: [ipv6-wg] IPv6 PI

On Thu, 24 Nov 2005, Florian Weimer wrote:
> * Roger Jorgensen:
> 
> > Can't we all just drop using the word multihoming and IPv6 PI? 
> > They all reflect back to how thing was done with IPv4 and those ways are 
> > doomed to fail with IPv6 simply due to the size of the IP space.
> 
> I'm a relative newcomer to this area.  Could you give a pointer to
> some explanation *why* the IPv6 address space size causes this
> problem?

Just do the math yourself and consider all possibilities and how the IPv4 
space are used... but some numbers

- the address space is 128bit.
- we have a 64bits host prefix at the lower end.
- the above give us 64bits of network numbers, that's quite a few billions 
of networks. BUT
- the /48 boundary leaving us with a usable globaly network space of 48bit
- from the 48bits only a /8 are usable as it is now, the other 7 /8 are 
reserved for the future.

The absolute max global routing table would by this be 40bits, of 
course the real one are alot smaller. That one is closer to 32bits, and 
that is STILL A huge number, probably more close to 20bits of entries.



a last comment: the entire idea behind /64 and /48 will cause IPv6 to fail 
as it is now. Odd as it is, we don't have enough IP space in IPv6. Sure it 
will last 10, maybe 15-20 years, but that did IPv4 to...... 



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Roger Jorgensen              |
rogerj at stud.cs.uit.no        | - IPv6 is The Key!
http://www.jorgensen.no      | roger at jorgensen.no
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