[ale] V6 question

Michael B. Trausch mike at trausch.us
Sat Feb 5 12:32:00 EST 2011


On Sat, 2011-02-05 at 11:31 -0500, Jim Lynch wrote:
> I'm truly sorry to have missed the talks on IPV6.  So how is it going
> to replace NAT?

You will receive a /64, /56, or /48 from your ISP.

There is no network address translation.

Remember that NAT was created in order to delay the exhaustion of IPv4
address space.  Most home and small-office networks use NAT solely for
the purpose of being able to have many systems access the Internet via
the same IP address (or via a limited pool of IP addresses)---nothing
more.

NAT is known to break many applications.  Some implementations of NAT
(such as the one that comes with the Linux kernel) include a number of
ALGs (ALG == application layer gateway) that provide helpers so that
such applications can more-or-less function, at the expense of increased
CPU, memory, and sometimes even bandwidth usage.

> I assume all the systems I have behind my router will have IPV6
> addresses.  Is that correct?

That would be correct.

There is a standards document (RFC 6092, informational) titled
"Recommended Simple Security Capabilities in Customer Premises Equipment
(CPE) for Providing Residential IPv6 Internet Service".  I have yet to
read it (it is on my reading list for today, in fact), but it talks
about basic security for IP, IPSec, IPv6 mobility, TCP, SCTP, and DCCP,
among others.  If desired, I will post a summary when I'm finished
reading it.

> Is DHCP going away?

There is DHCP for IPv6 (DHCPv6) but it is not likely to be used on most
networks.  IPv6 has stateless autoconfiguration which relies on neighbor
discovery (the IPv6 equivalent to IPv4's use of ARP) and router
advertisement.  The idea is that when you have an IPv6 router on the
network, it will periodically advertise itself.  Your operating system
will see the advertisement and configure the IPv6 address and routing
tables accordingly.  For multihomed hosts, this means that you can have
a system on two networks and it will obtain an address from both
networks automatically (of course, it will not behave as a router unless
IPv6 forwarding is turned on).

I don't see DHCP being used on small networks, and probably not on
medium-sized networks, either.  Stateless autoconfiguration is simple
and it works out of the box; the addresses that a system obtains using
it are going to be the same every time, as well.  This means that you
can add the addresses to DNS and they will work just fine.  The only
thing that I don't think currently works is DNS resolver configuration,
though that's a simple enough matter to handle.

> So is the port the ISP furnishes me going to be just a connection to
> the wan without a IP address?

The ISP should provide a router that advertises.  Your systems should
pick up the addresses.  Simple, easy.  :-)

	--- Mike
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