[Gllug] Public IPs - When are they appropriate

[Paul Brazier]

> Er, no; MAC addresses are 6 octets (and you'll notice no-one is
> worried about running out of those.)
> 
> IPv6 addresses are 16 octets - 2^128 addresses; 3.4x10^38.

That'll teach me to check before posting :) 
For some reason I was under the impression that IPv6 was 6 sets of
octets - maybe the "6" in the name corrupted my memory.
 
> Even if we assume that the last 6 octets of the IPv6 address will be
> the MAC address - so the unicast addresses effectively only offer
> 2^(125-48) addresses - 2^77 - that's still 1.5x10^23, or 5x 10^8 per
> square meter of the Earth's surface.

So does this mean that if you change your ethernet card you'll have to
change your IPv6 address?
What about "dead" computers - will their IPv6 addresses be recyclable?
It seems a bit strange to have physical and logical in the same scheme.
 
> [There's an obvious fallacy there in that not all those 2^77 devices
> can have one of the 2^48 MAC addresses - but even if all devices have
> a MAC address, 2^48 MAC addresses is 2.8 x 10^14. Which is probably
> where this 'one per square meter' confusion comes from.]

Maybe one MAC address would have several IPv6 addresses mapped to it?
Like if you have a single machine using IP virtual hosting. I think the
popularity of name-based virtual hosting came about because of the
shortage of IP addresses?

(Forgive me if I'm taking rubbish again ;))


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