[AusNOG] My Predictions for the ISP Industry

[Mattia Rossi]

On 16/03/2012 16:29, Mark Andrews wrote:
> In message<4F62C921.9090600 at swin.edu.au>, Mattia Rossi writes:
>>>
>>>    >   This means that the
>>>    >   CPE is creating a 6to4 prefix out of it's public facing IPv4 address,
>>>    >   which is then used to distribute v6 addresses to all his IPv6 devices in
>>>    >   the house.
>>>
>>> More or less.  Or some other prefix.  But yes.
>>>
>>
>> Some other prefix? E.g. fc00::/7 ?
>
> You get to play with lots of addrsses and prefixes with IPv6.
>
> en1: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST>  mtu 1500
> 	ether 60:33:4b:01:75:85
> 	inet6 fe80::6233:4bff:fe01:7585%en1 prefixlen 64 scopeid 0x5
> 	inet 192.168.191.223 netmask 0xffffff00 broadcast 192.168.191.255
> 	inet6 fd92:7065:b8e::6233:4bff:fe01:7585 prefixlen 64 autoconf
> 	inet6 fd92:7065:b8e::5dfc:57b0:350:c254 prefixlen 64 autoconf temporary
> 	inet6 2001:470:1f00:820:6233:4bff:fe01:7585 prefixlen 64 autoconf
> 	inet6 2001:470:1f00:820:b12a:d75d:86e6:f3b3 prefixlen 64 autoconf temporary
>
> 3 prefixes and 5 addresses.
> fe80::/64 link local
> 	fe80::6233:4bff:fe01:7585%en1
>
> fd92:7065:b8e::/64 ULA internal communiction.
> 	fd92:7065:b8e::6233:4bff:fe01:7585  mostly servers, long lived
> 	fd92:7065:b8e::5dfc:57b0:350:c254   clients, short lived
>
> 2001:470:1f00:820:/64 HE tunneled prefix, external communiction.
> 	2001:470:1f00:820:6233:4bff:fe01:7585 mostly servers, long lived
> 	2001:470:1f00:820:b12a:d75d:86e6:f3b3 clients, short lived
>

Exactly, that's what I meant: you have either a link local, or a ULA, or 
in your case a 2001 prefix via the tunnel.

So a 6to4 enabled CPE provides to the LAN hosts either link local 
(provides is probably the wrong term here), or a ULA or a 2002 based 
address. It can't get any 2001 or other global unicast prefix one, 
unless you manually set that up.

Given that ULAs and link locals can't leave the LAN, the hosts need to 
use the 2002 addresses as source to get out (actually for packets to get 
back), or the CPE will have to do some weirdness with the other types of 
addresses (e.g. NAT).

Mat