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SubjectRe: IPv6 and the "average user" (Bas Mevissen) wrote on 21.11.96 in <>:

> > o There are not enough IPv4 addresses. Just to put all the cable
> > TV customers in the USA on couldnt be done. Abortions like dynamic
> > IP are directly due to this
> Or are dynamic IP's invented because there where not enough IPv4 addresses
> to give all users their own IP !

No. There are still a lot of free IPv4 addresses around.

It's the routers who are starting to melt down. Backbone routers are
currently working near their maximum capacity for routing tables. It is
expected that they will break down sometime between 2000 and 2010 if
nothing is done.

To keep them alive as long as possible, routes need to have long prefixes
- or, to put that differently, providers have to share one or very few
prefixes among all their customers.

And *that* makes for too few IP addresses for every customer.

There would be enough IP addresses to give, say, every customer of AOL a
fixed IP address. But to do so, the routing table entries for AOL, for non-
AOL routers, would need to be at least doubled. Same for other providers.

IPv6 helps there because, with the same number of prefixes (actually, less
of those - all the *old* IPv4 addresses are outside of shared prefixes,
which is part of the problem), you have a lot more bits left to do your
local stuff.

The current plan is that IPv6 addresses should usually be configured
automatically, with the lowest 48 bit using the ethernet address of the
machine, and the next 16 bits available for subnetting at the customer,
and the other 64 bit available for ISP prefix and customer identification
at the ISP. With IPv4, you need a class A address to similar stuff. There
are currently less than 100 organizations with class A networks, while
under IPv6, there will probably eventually be millions of customers with
that capability ...

My guess is that with IPv6, giving customers a range of addresses to use
will become standard. Currently, ISPs don't want to give out even a single
permanent address!

However, you'll still need to change your addresses when you switch ISPs,
unless you are big enough so the backbone routers will be willing to make
routing table entries just for you. Because of this, renumbering a network
is a lot easier in IPv6 - each box *must* support being told their address
by the router. At the router, just configure the new 80 bit prefix. The
rest is automatic. (Well, if you do DNS, you'll have to change that, too.)

MfG Kai

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