Brian Johnson wrote:
Last time I checked, and this may have changed, the limit in Linux was around 4096.
So in this circumstance you could route a /116 to the server. COOL!
These days what we might at one point have refered to as a host or server may actually be a hardware container with N > 1 or so virtual systems... which may variously be: attached to the network via dedicated interface individual vlans a virtual bridge a layer-3 topology
In practice though, you also have to consider the physical limitations of the server itself. The biggest bang for the buck in dense hosting environments seems to be running about 1000 sites per box, with a few boxes dedicated to your heavy hitters with 100 or less ea.
So in this circumstance you could route a /118 to the server serving 1000 sites and a /125 to the server serving 100 sites. Also COOL!
How many ips you can park on a particular hardware container is probably bounded only by the over-subscription rate of what you intend to serve. Most of the superficial limits (macs on a bridge table, ips on an interface etc can be worked around in fairly simple fashion but the number of connections per second or pps rate a given hardware container can pass though whatever abstraction is applied is less fungible.
Until we start seeing IPv6-only hosting though, I suspect that we will see IPv6 address mirror the configuration of the IP assignments. Sites with dedicated IPs will have dedicated IPv6, sites with shared IP will have shared IPv6, if only to maintain sanity.
This passes my smell and duh tests. :)
If you're trying to make the case for IPv6 to hosting companies, you're barking up the wrong tree. IP address just became a scarce commodity, instead of providing you with a free IP address, the can now charge $100 a mo for one. They know darn well that it will take a while for every user to have IPv6 from their SP and that if you want to run a site you'll need access to the "legacy" IP Internet to reach your customers. On the bright side, this will encourage the market to adopt IPv6 because they can't afford IP. Hopefully ARIN adopts a policy of decommissioning IP space as they reclaim it to prevent people from receiving new allocations as people begin to go IPv6-only, otherwise we'll be stuck with two Internets for a very long time.
Agreed, except for one thing. ARIN shouldn't "decommission" IP space. The Internet will dictate that IPv4 will go away all on its own once IPv6 becomes the protocol of choice for enough of the net. At some point, the people who depend on IPv4 will not be able to pay for their providers supporting the IPv4 infrastructure as new devices become available that either only support IPv6, or don't implement a full suite of IPv4 to keep costs down.
Also remember that at some point, there will be no IPv4 left. When this happens new entrants will suffer greatly at the hands of this circumstance. But we will get through it and there will be new sites that will be IPv6 only, then there will be demand for these sites, then there will be people who vote with their wallets for the new sites...
Was I rambling there? :) In the end it will be economics that dictate a single protocol Internet. I am one who wishes we put a date in stone now to establish the "cut date" of IPv4 to IPv6, but that is unreasonable. This will take care of itself.
_____________________________________ Brian Johnson Converged Network Engineer (CCNP, ENA) Dickey Rural Networks