On 1/25/2010 4:45 AM, Richard A Steenbergen wrote:
On Mon, Jan 25, 2010 at 09:12:49AM +0000, Andy Davidson wrote:
There are 4,294,967,296 /64s in my own /32 allocation. If we only ever use 2000::/3 on the internet, I make that 2,305,843,009,213,693,952 /64s. This is enough to fill over seven Lake Eries. The total amount of ipv6 address space is exponentially larger still - I have just looked at 2000::/3 in these maths.
THE IPv6 ADDRESS SPACE IS VERY, VERY, VERY BIG.
Don't get carried away with all of that "IPv6 is huge" math, it quickly deteriorates when you start digging into it. Auto-configuration reduces it from 340282366920938463463374607431768211456 to 18446744073709551616 (that's 0.000000000000000005% of the original 128 bit space). Now as an end user you might get anything ranging from a /56 to a /64, that's only between 1 - 256 IPs, barely a significant increase at all if you were to actually use a /64 for each routed IP rather than as each routed subnet. As a small network you might get a /48, so that even if you gave out /64s to everyone it would be only 16 bits of space for you (the equivalent of getting a class B back in IPv4 land), something like a 8-16 bit improvement over what a similar sized network would have gotten in IPv4. As a bigger ISP you might get a /32, but it's the same thing, only 16 bits of space when you have to give out /48s. All we've really done is buy ourselves an 8 to 16 bit improvement at every level of allocation space (and a lot of prefix bloat for when we start using more than 2000::/3), which is a FAR cry from the 2^128 "omg big number, we can give every molecule an IPv6 address" math of the popular imagination. :)
And it does not account for the factor that I was trying to shine a light on--the it-is-infinitely-huge is at risk of failing due to inventions we can not conceive of. Who knew, in the 1940's that every person would be assigned as many as five or more telephone numbers (exaggeration? In this house, occupied by two people there are 4 addressable PSTN devices, only one of which leaves the house if one of us does, and there are 6 devices that share an address but could easily have individual addresses, and would if we were using one of the VOIP services). Who knew in the 1980's that refrigerator's would need IP addresses? (We should not have been surprised, Coke machines did.) And for all the concern about IPv4 exhaustion, what would have happened if the people who fought fiercely against RFC 1918 had won the day? Yes the numbers in IPv6 are huge, no doubt about it. But I say, to say "impossible to exhaust" is a fools errand. Somebody will find a way to exhaust the pool, just to be contrary, if for no currently recognized "legitimate" reason. -- "Government big enough to supply everything you need is big enough to take everything you have." Remember: The Ark was built by amateurs, the Titanic by professionals. Requiescas in pace o email Ex turpi causa non oritur actio Eppure si rinfresca ICBM Targeting Information: http://tinyurl.com/4sqczs http://tinyurl.com/7tp8ml