Using IPv6 with prefixes shorter than a /64 on a LAN

Mark Andrews marka at isc.org
Fri Feb 4 17:11:34 CST 2011


In message <4D4C0D25.70408 at brightok.net>, Jack Bates writes:
> 
> 
> On 2/4/2011 5:03 AM, Eugen Leitl wrote:
> 
> > Given http://weblog.chrisgrundemann.com/index.php/2009/how-much-ipv6-is-the
> re/
> > it is pretty clear the allocation algorithms have to change, or the resourc
> e
> > is just as finite as the one we ran out yesterday.
> 
> That's not what the author says. It says, IPv6 is only somewherein the 
> range of 16 million to 17 billion times larger than IPv4.

And the author gets it wrong.

> Let's be realistic. A /32 (standard small ISP) is equiv to an IPv4 
> single IP.

No, a /48 is equivalent to a single IP.

You loose a little bit with small ISPs as their minimum is a /32
and supports up to 64000 customers.  The bigger ISPs don't get to
waste addresses space.  And if a small ISP is getting space from
a big ISP it also needs to maintain good usage ratios.

> A /28 (medium ISP) is equiv to an IPv4 /28. A /24 (high 
> medium, large ISP) is equiv to an IPv4 /24. A /16 (a huge ISP) is equiv 
> to an IPv4 /16. Get the picture?
> 
> So, I currently route a /16 worth of deaggregated IPv4 address space 
> (sorry, allocation policy fault, not mine). There is NEVER a time that I 
> will be allocated an IPv6 /16 from ARIN. Heck, the most I'll ever hope 
> for is the current proposal's nibble boundary which might get me to a 
> /24. I'll never talk to ARIN again after that.
> 
> 
> Jack
> 
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org




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