Slashdot: UK ISP PlusNet Testing Carrier-Grade NAT Instead of IPv6

Mark Andrews marka at isc.org
Thu Jan 17 02:20:35 UTC 2013


In message <50F70524.4020102 at fredan.se>, fredrik danerklint writes:
> >> Even tough you have very good arguments, my suggestion would be to have a
> >> class A network (I got that right, right?) for all the users and only havi
> ng
> >> 6rd as service on that network.
> >
> > ARIN and IETF cooperated last year to allocate 100.64.0.0/10 for CGN
> > use. See RFC 6598. This makes it possible to implement a CGN while
> > conflicting with neither the user's RFC1918 activity nor the general
> > Internet's use of assigned addresses. Hijacking a /8 somewhere instead
> > is probably not a great move.
> 
> Ok.
> 
> If I have calculated the netmasks right that would mean to set aside:
> 
> 2001:0DB8:6440::/42
> 
> for the use of 6rd service:
> 
> 2001:0DB8:6440:0000::/64 = 100.64.0.0
> ....
> 2001:0DB8:647F:FFFF::/64 = 100.127.255.255

No.  With 6rd you DROP the top 10 bits and you give every customer
a /56. And you can repeat the exercise 4 times within a /32.

/etc/dhcpd.conf:
subnet 100.64.0.0 netmask 255.240.0.0 {
	range 100.64.0.2 100.64.255.254;
	router 100.64.0.1;
	option 6rd 10 34 2001:DB8:: 2001:DB8::1;
}
subnet 100.64.0.0 netmask 255.240.0.0 {
	range 100.64.0.2 100.64.255.254;
	router 100.64.0.1;
	option 6rd 10 34 2001:DB8:4000: 2001:DB8:4000:1;
}
subnet 100.64.0.0 netmask 255.240.0.0 {
	range 100.64.0.2 100.64.255.254;
	router 100.64.0.1;
	option 6rd 10 34 2001:DB8:8000: 2001:DB8:8000:1;
}
subnet 100.64.0.0 netmask 255.240.0.0 {
	range 100.64.0.2 100.64.255.254;
	router 100.64.0.1;
	option 6rd 10 34 2001:DB8:c000: 2001:DB8:C000:1;
}

-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org



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