On 10/16/08 02:16, Petr Pisar wrote:
`Translating' is not proper word unless you mean real NAT-PT (Network
address translation and protocol translation).
I was going to use the term "gatewaying" to describe what needed to be
done between the IPv6 and the IPv4 protocols. "Translating" is usually
done /with in/ a single protocol and "gatewaying" is usually done
/between/ two protocols. At least that's my take on it.
If you want just to connect your IPv6 island via IPv4 Internet to
native IPv6 Internet backbone (i.e. bypass your lazy ISP), use 6to4
(in case you have public IPv4 address on your gateway) or AYIYA (in
other case). This is called tunneling and former post enlightened it
already.
*nod*
If you want to be able to connect from your IPv6 host to IPv4 only
servers in IPv4 Internet, you have to choices:
Provide to all IPv6 hosts IPv4 connectivity (i.e. dual stack
solution), or do NAT-PT on your gateway.
I think the OP is wanting to avoid dual stack despite this probably
being the simpler of the options.
NAT-PT translates one protocol family into other one. However due to
some differences between these two protocols, the translation is not
seamless (like IPv4 NAPT). Thus there exist few limitations and
different solutions how to achieve it.
I know only about RFC3142 (An IPv6-to-IPv4 Transport Relay
Translator) implementation and it's pTRTd
<http://www.litech.org/ptrtd/> and totd
(http://www.vermicelli.pasta.cs.uit.no/software/totd.html). It works
following:
IPv6 only client asks totd name server for AAAA record of IPv4 only
host. The name server provides fake answer resolving to network
prefix routed to pTRTd server. Then your client sends IPv6 TCP or UDP
packet to given fake IPv6 address, the packet recieves pTRTd server
(a userspace daemon capturing packets on TUN network interface),
pTRTd established mapping between IPv6 and IPv4 transport addresses,
translates the packet into IPv4 protocol and transmits it to the real
IPv4 only host in IPv4 Internet. Of course the pTRTd processes
returing responses and forward them to your IPv6 client as IPv6
packets.
Thus your IPv6 only hosts can see whole IPv4 world as a subnet in
IPv6 address space.
Very interesting!
I now have a reason to mess with IPv6.
Grant. . . .
P.S. Very good reply. I was going to try to sum up the bit about
translation verses gatewaying, but I think you did a better job than I
could have.
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