Stupid Ipv6 question...

Fri Nov 19 15:36:11 UTC 2004

Thus spake "Dan Mahoney, System Admin" <danm at prime.gushi.org>
> I'm having trouble wrapping my head around ipv6 style suffixes -- does 
> anyone have a chart handy?  How big is a /64, specifically?

Subnet sizes work a bit differently in IPv6 due to autoconfiguration; nearly 
all subnets are expected to be /64, which can hold up to 
18,446,744,073,709,551,616 hosts.  A /48, the minimum assignment to end 
sites (unless proven to need only a single /64), comprises 65,536 subnets. 
A /32, the minimum allocation to ISPs, comprises 65,536 /48s.  Of course, 
the minimum allocation sizes may be changed (up or down) in the future by 
RIR policy actions, and ISPs or end-sites can get shorter prefixes with 
proper justification.

/127 prefixes are assumed for point-to-point links, and presumably an 
organization will divide up a single /64 for all ptp links -- unless they 
have more than 9,223,372,036,854,775,808 of them.

S

Stephen Sprunk         "God does not play dice."  --Albert Einstein
CCIE #3723         "God is an inveterate gambler, and He throws the
K5SSS        dice at every possible opportunity." --Stephen Hawking 