[ale] V6 question

[Michael H. Warfield]

Oh, where shall I begin.

First off...  My slide deck from my ALE presentation is here in several
formats:

http://www.wittsend.com/mhw/2011/IPv6-BNW-ALE-2011.odp
http://www.wittsend.com/mhw/2011/IPv6-BNW-ALE-2011.pdf
http://www.wittsend.com/mhw/2011/IPv6-BNW-ALE-2011.ppt

Some of that might help.  Aaron informs me that he's tied up on a paid
assignment (which absolutely takes priority in my book) for the next
couple of weeks so it may be awhile before he has the recording ready.
When he does, either he or I will post it as well.  That will help some
more.

Now to try and answer your questions...


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?

Simple answer.  It won't.  NAT (more specifically and precisely) NAT44
(NAT IPv4:IPv4) will always be with us as long as IPv4 remains
supported.  IPv6 does not have or support NAT.  It doesn't need it.

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

That is correct.  Just as all your systems now have IPv4 addresses.
Difference is, the v6 addresses of your systems will be global unicast
addresses (in addition to a variety of multicast and link-local
addresses) while the v4 systems have "private addresses" (in v6 land we
call them site-local addresses).

Example...  On my laptop right now, here are my addresses: 

eth0      Link encap:Ethernet  HWaddr 00:24:7E:E1:2A:A7  
          inet addr:130.205.38.43  Bcast:130.205.38.255  Mask:255.255.255.0
          inet6 addr: 2001:4830:3000:8200:224:7eff:fee1:2aa7/64 Scope:Global
          inet6 addr: fe80::224:7eff:fee1:2aa7/64 Scope:Link

The first one is my IPv4 address (I have lots of public addresses so I
don't need to use NAT at all so that's a global v4 address in this
case).  The second one is my IPv6 global address.  The third one is my
link-local address (Note the "Scope:" field).

> Is DHCP going away?

It might.  It might not.

IPv4 has two methods for configuring addreses.  Static, and stateful
autoconfiguration (dhcp).  IPv6 has those plus it adds stateless
autoconfiguration.

Static works the same way in both.  You code the addresses into the
system.

Stateful works in a similar way.  On IPv4, it's dhcp.  On IPv6 it's
dhcp6.  So no, if you want to use stateful autoconfiguration, you just
run a new dhcp daemon only on the v6 service.  On IPv6, dhcp does work a
little different than on IPv4 because dhcp6 uses multicast addressing
(IPv6 has no broadcast addresses at all) but the principle remains the
same.

Stateless autoconfiguration involves router advertisements and router
discovery along with neighbor discovery.  You can think of these sorts
of things is like "arp on steriods" extended to cover things arp
doesn't.  If you look at my addresses above, you'll see the numbers
after the "fe80::" are identical to the numbers after the
"2001:4830:3000:8200:".  That my EUI (End Unit Identifier) or host
identifier field.  That's the local part of your address and the system
automatically computes this from your MAC (HWaddr above).  Compare them.
You can see the similarity.

So, where did the "2001:4830:3000:8200" come from?  It came from the
router.  The router is broadcasting this prefix periodically and when a
system first comes up, it sends a request to the "all routers" multicast
address and solicits the routers to send it a prefix.  It takes that
prefix and combines it with its EUI and voila, you have a global
address.  So, if you want to go that route, no, you don't need dhcp.

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

No.  They will assign you a prefix.  I now understand that Comcast is
handing out /64 prefixes (single subnet) to customers participating in
their beta rollout.  In principle, if you have multiple subnets, you
were originally suppose to get a /48 (that's 65,536 subnets for you) but
that's a bit much for residential customers.  Freenet6 hands out
free /56 networks (256 subnets).  I don't know how Comcast is going to
deal with that down the road.  Maybe a request or on demand for subnets.

Once you get a prefix, your router will advertise that prefix and all
your machines will number themselves.

> I'm confused.

> Jim.

Regards,
Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
   /\/\|=mhw=|\/\/          | (678) 463-0932 |  http://www.wittsend.com/mhw/
   NIC whois: MHW9          | An optimist believes we live in the best of all
 PGP Key: 0x674627FF        | possible worlds.  A pessimist is sure of it!
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