On 5/02/2009, at 3:09 PM, Matthew Moyle-Croft wrote:
TJ wrote:
No, we should hand each home a /56 (or perhaps a /48, for the
purists out
there) - allowing for multiple segments (aka subnet, aka links,
etc.).
If there are, say, 250-500 million broadband services in the world
(probably more) then, if every ISP followed best practise for IPv6
address allocation, (sparse, bits for infrastructure, whatever etc)
then what percentage of the space do we have left if we hand out /56
or /48s?). Taking into account the space already carved off for
link local, private addressing, US Military etc.
Has anyone done some analysis of what this might look like?
Especially with growth etc.
My addressing plan works like this:
ISP gets /32, 2001:db8::/32
- 2001:db8:0::/48 = ISP use
-- 2001:db8:0:0::/64 = infrastructure
--- 2001:db8:0:0:0:0:0::/112 = loopbacks ( 65536 )
--- 2001:db8:0:0:1:0:0::/112 through 2001:db8::ffff:ffff:ffff:0/112 = /
112 link nets between ISP routers ( 281474976710656 )
-- 2001:db8:0::/64 through 2001:db8:0:ffff::/64 = ISP networks, ie.
servers, etc.
- 2001:db8:1::/64 through 2001:db8:ffff:ffff::/64 = customer networks.
Assuming the above, we have 65535 /48s available to customers, or
16,711,680 /56s.
The "ISP use" /48 burns 256 /56s, or potential customers. So, like
burning a /24 for the entire ISP operation.
So, if you have more than 65K business customers, get more than a /32.
If you have more than 16M residential or small business customers, get
more than /32.
The above plan puts the addresses you type lots (loopbacks, link nets)
on the shortest addresses you have - you can use the zero
compression :: thing. These are also the addresses that cause the most
trouble if fat fingered, so shorter addresses leave less room for error.
In addition, the entire first /64 (loopbacks, link nets) should never
really receive packets from outside the network. Drop in an ACL.
Modification to the above plan is to use /64s for link nets between
ISP routers, if you are worried about compatibility issues. You now
have a trade off between 65k ISP server networks, and 65k link nets.
Let's say 32k for each.
--
Nathan Ward
