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

Fri Feb 4 16:50:01 UTC 2011

On Fri, Feb 04, 2011 at 08:28:53AM -0600, Jack Bates wrote:
> 
> 
> On 2/4/2011 5:03 AM, Eugen Leitl wrote:
> 
> >Given 
> >http://weblog.chrisgrundemann.com/index.php/2009/how-much-ipv6-is-there/
> >it is pretty clear the allocation algorithms have to change, or the 
> >resource
> >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.

	presuming you don't adhere to the guidelines that
	insist on the bottom 64 bits being used as a "MAC" address
	and the top 32 bits being used as an RIR identifier.

	in reality, IPv6 (as specified by many IETF RFCs and as implemented
	in lots of codes bases) only has 32 usable bits... just like IPv4.

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

	sho'huff.  the real question is, how will you manage your own 32bits
	of space?  this is a change from the old v4 world, when the question
	was, how will you manage your (pre CIDR) 8bits (or 16bits, or 24bits) 
	of space?
> 
> Jack

	I suspect that many people will do stupid things in managing their
	bits - presuming that there is virtually infinate 'greenfield' and 
	when they have "pissed in the pool" they can just move on to a new 
	pool.  the downside... renumbering is never easy - even with/especially
	with IPv6.

--bill