On 10/7/11 2:41 PM, Lorenzo Colitti wrote:
Seems like we'd like to be able to introduce IPv6 support without
NATs into such a home network without breaking IPv4.
This approach doesn't break IPv4, but it will work regardless of whether
IPv4 is working or not. So if/when IPv4 goes away you can plug any port
into any other port, even in topologies that IPv4+NAT can't handle, and
it will still work.
I don't think "doesn't work if IPv4 doesn't work" should be a goal.
You seem to focus on a clean slate approach.
More than clean slate it's ships in the night.
So if we take a topology below (if it doesn't display correctly, look at
figure 7 in
http://tools.ietf.org/html/draft-chakrabarti-homenet-prefix-alloc-00)
+------+--------+ \
| IPv6 | \
| Customer Edge | \
| Router 1 | |
+------+--------+ +------------+ |
Network A | | | |
+-------------+------+-------+-------+-----+ | |
| | | | | | |
+----+-----+ +-----+----+ | +----+-----+ +-----+----+ | |
|IPv6 Host | |IPv6 Host | | | IPv6 | |IPv6 Host | | |
| | | | | | Router 2| | | | |
+----------+ +----------+ | +----+-----+ +----------+ | |
| | | |
| +-------------+ | |
| | Network B | | |
| | | | |
| +----+-----+ +-----+----+ | |
| | IPv6 | |IPv6 Host | | |
| | Router 3| | | | |
| +----+-----+ +----------+ | |
| | | |
| +--------------------+ |
| Network C/A |
+------+--------+ | End-User
| IPv6 | | networks
| Router 4 | |
+------+--------+ |
Network D | |
+-------------+------+--------+---------+ |
| | | | |
+----+-----+ +-----+----+ +----+-----+ +-+------+-+ |
|IPv6 Host | |IPv6 Host | | IPv6 Host| |IPv6 Host | |
| | | | | | | | /
+----------+ +----------+ +----------+ +----------+ /
If this was an IPv4/NAT network it wouldn't reliably work, since there
is a NAT loop involving R3 and R2. Thus in IPv4 the link out of the
bottom of R3 would actually not exist.
I think what you are saying is that it is fine if the deployment of IPv6
encourages folks to create the R3/R2 loop above, even if that makes IPv4
fail.
I find such an approach rather unrealistic; it might be reasonable in
greenfield IPv6-only home networks but I would never recommend that as a
way to move current IPv4 home networks forward.
I thought we wanted the solution to apply to the average Joe, and not
just experts like ourselves.
Regards,
Erik
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