Diffrences: IPv4 vs IPv6

Robert E. Seastrom rs at seastrom.com
Wed Jan 25 15:43:04 CST 2012

As a practical matter, if you turn rtadvd on and off on the router,
you'll be turning on and off the hosts on the networks' concept of
whether they can get IPv6 or not.  Dunno if you have Macs or Linux or
Windows or what floating around the house, but so long as you turn off
the v6 router advertisement, having a broken tunnel or whatever won't
get in your way.


Alex Fraser <beatnic at comcast.net> writes:

> Oh boy a project!  It's good I got the reply so quick as I have to got to the store anyway and can put the Almond M&M's on the
> shopping list ;-)
> I will start digesting the info.  It looks like we have a couple of rain days coming up which is always a good time to sit inside and
> play with computers.  It also just occurred to me that my dear wife is going out of town for a bunch of days which will allow me to
> really screw up the home network (and have a chance to fix it) while she is gone.  She must be able to shop online!
> A quick question.   Will I be able to build my local net and then switch on and switch off  the IPv6 tunneling?  I'm assuming it is a
> configurable option in my local router, is this correct?
> Robert E. Seastrom wrote:
>           Alex Fraser [[<beatnic at comcast.net>]] writes:
>                     I would like to start playing with IPv6.   I'm retired, my
> experimental net would be paid for out of my "toy money", so cost is
> important.  I'm connected to the internet through Comcast. I'm
> assuming  (but don't really know) that I can have a home network
> connected to the internet using IPv6.  I'm fairly comfortable with a
> couple of flavors of Linux, but have a couple of workhorse XP
> machines.  I use a Linksys wireless router connected to the cable
> modem, which uses NAT to give my home computers addresses which they
> pick up with DHCP.
>      So far so good.  You're in a great position to run IPv6 at home.
>                     So assuming I can get the Comcast cable modem to use IPv6, could I
> get a new image to burn into my Linksys router to let it route IPv6
> to my home network.  I have a couple of the Linksys boxes running
> dd-wrt now.  It would be sweet to have IPv4 and IPv6 running on my
> home net at the same time so I could phase in the upgrade.  So where
> do I start? Must I register for some IPv6 addresses to use at home
> or is there an equivalent of the non routable NAT address blocks
> like in IPv4?
>      OK, so let's start with a few points:
> You don't register IPv6 space from a central registry yourself for
> your home, just like you don't for IPv4.  You get it from an "upstream
> ISP", but in the case of Comcast, though they're running trials it's
> not something you can get "on demand" from them.  So you have to
> tunnel it in over IPv4 using a protocol called "6in4".  This is a very
> close cousin of the "IP in IP" encapsulation that KA9Q NOS has run for
> 20 years or so - it's just building a tunnel to an upstream ISP which
> you can get IPv6 connectivity from.  These folks are called "tunnel
> brokers".  Hurricane Electric is a popular one that has a tunnel
> endpoint box in Ashburn.
> [[http://tunnelbroker.net/]]
> The good news is that (assuming you're running a relatively new, and
> not stripped-down-due-to-having-shitty hardware copy) DD-WRT supports
> IPv6 out of the box, and there are howto documents that should get you started.
> [[http://www.dd-wrt.com/wiki/index.php/IPv6]]
> Hurricane will give you a /48, or /64 prefix (I think) for your end
> site depending on what you ask for.  Remember that a /64 is a single
> LAN (LANs are always /64 - there are advantages and disadvantages to
> this as others on the list can tell you), but the upshot is that you
> never have to worry about how much space for host addresses you have
> on the network since just as there are 64 bits in the prefix, there
> are 64 bits in the host section, meaning a theoretical 2^64 hosts on
> the network.  How big is 2^64?  If you drained all five Great Lakes
> and filled them with almond M&Ms, you would have about 2^64 M&Ms...
> and 2^65 calories...  which corellates with a weight gain of about
> 3*10^61 pounds.  I gotta get back on my diet.
> You don't NAT IPv6 traffic - you can put in a firewall/filter in your
> dd-wrt router to express policy about who can talk to your machines,
> but NAT is a big pain in the butt and requires working around.
> With the instructions I've linked you to, you should be able to get
> IPv6 up and running in an evening.
> If you're running Linux of a Mac, stateless autoconfiguration should
> do the job and you'll get an IPv6 address:
> Billet:~ rs$ ifconfig en1
>      ether 00:26:bb:0e:f3:33 
>      inet6 fe80::226:bbff:fe0e:f333%en1 prefixlen 64 scopeid 0x5 
>      inet netmask 0xfffffe00 broadcast
>      inet6 2610:178:1:2:226:bbff:fe0e:f333 prefixlen 64 autoconf 
>      media: autoselect
>      status: active
> Billet:~ rs$ 
> Note that I have two IPv6 addresses on my wireless interface here: a
> link-local address (the one that starts with fe80::) and a globally
> unique one (the one that starts with 2610:178).  The Mac picked up its
> address via stateless autoconfig.  MacOSX 10.7 "Lion" does DHCPv6 too.
> The utilities for testing IPv6 are ping6 and traceroute6, thus:
> Billet:~ rs$ ping6 ipv6.google.com
> PING6(56=40+8+8 bytes) 2610:178:1:2:226:bbff:fe0e:f333 --> 2001:4860:800e::68
> 16 bytes from 2001:4860:800e::68, icmp_seq=0 hlim=55 time=34.783 ms
> 16 bytes from 2001:4860:800e::68, icmp_seq=1 hlim=55 time=27.008 ms
> 16 bytes from 2001:4860:800e::68, icmp_seq=2 hlim=55 time=26.834 ms
> ^C
> --- ipv6.l.google.com ping6 statistics ---
> 3 packets transmitted, 3 packets received, 0.0% packet loss
> round-trip min/avg/max/std-dev = 26.834/29.542/34.783/3.707 ms
> Billet:~ rs$ 
> Success!
> Let me know how things work out for you, and if you need any more help
> or if I've glossed over stuff that has left you with an information
> gap.
> -r
> -- 
>    \\\\\\\\\\\\\\\\-----++++*0*++++-----//////////////////
>        No electrons were harmed in the creation of this message
>          --------------------------------------------------------
>  ~~~********************Alex Fraser********************~~~
>          --------------------------------------------------------
> [[[[[[~~^^^#___=>>>```/\/\**O**/\/\```<<<=___#^^^~~]]]]]]
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