Basic abstract of the e-mail:
In RFC 1183, an experimental DNS RR type is defined called the Route
Through (RT) RR. Although not its original purpose, could this be
expanded and used to ease the IPv4 to IPv6 transition?
---
A simple state table gives us 9 possibilities:
# | Endpoint A | Endpoint B
---------------------------
1 | IPv4 only | IPv4 only
2 | IPv4 only | IPv4/6
3 | IPv4 only | IPv6 only
4 | IPv4/6 | IPv4 only
5 | IPv4/6 | IPv4/6
6 | IPv4/6 | IPv6 only
7 | IPv6 only | IPv4 only
8 | IPv6 only | IPv4/6
9 | IPv6 only | IPv6 only
You might argue that some of the entries on the list are duplicates
since #4 is just #2 reversed, etc. But I'll leave it as is for now.
Assuming some way to route the native networks:
Case #1: No connectivity problems.
Case #2: Can connect with the IPv4 addresses.
Case #3: Uh-oh. Need some way to connect. See below.
Case #4: Can connect with the IPv4 addresses.
Case #5: Can connect with either the IPv4 or IPv6 addresses. (Which one
is a different topic and should be branched off from this thread.)
Case #6: Can connect with the IPv6 addresses.
Case #7: Uh-oh. Need some way to connect. See below.
Case #8: Can connect with the IPv6 addresses.
Case #9: No connectivity problems.
So, concerning Case #3 and Case #7, which is basically a IPv4 host on
one end and a IPv6 host on the other:
If a IPv6-only host wants to connect to a IPv4-only host, could an RT
record be used to point the IPv6 machine to a suitable IPv6-to-IPv4 gateway?
* Perhaps a company would rather not (or cannot) change over their
production IPv4 machines, but don't want to leave IPv6 customers in the
dark. They would perform a simple DNS addition along with a gateway of
sorts. (Maybe the "gateway" is a paid service of the ISP?) The "gateway"
would have an IPv6 address and know how to simply bridge/relay traffic
to and from a particular IPv4 address. This would make it very simple
to "upgrade" existing IPv4 services to allow IPv6 traffic, without
modifying existing systems.
(1) Would something like the above work?
(2) If yes, what would it take to implement?
(3) If no, what is a workable idea that can be implemented? (no reason
to respond unless you can suggest an alternative or improvement)
I view those as separate, yet related, discussions.
On the other hand, if an IPv4-only host wants to connect to a IPv6-only
host, could an RT record be used to point the IPv4 machine to a suitable
IPv4-to-IPv6 gateway?
* This scenario is a little trickier since one probably couldn't be able
to provide a IPv4-to-IPv6 bridging service for all of their hosts.
Plus, I doubt the IPv4 hosts are going to be updated to look for RT
records anyway. So, this RT idea doesn't really cover this situation...
Perhaps a relay system could be built where a single IPv4 address maps
different ports to different IPv6 boxes. For example, port 25 -> IPv6
SMTP server, and port 80 -> IPv6 HTTP server. Either way, that's just a
thought and perhaps should be split off into a different thread.
There's probably already a name I don't know for what I just described
there.
(4) What is the best way to handle IPv4 connecting to IPv6 services?
[new thread]
Well, that turned out to be much longer than I thought and took me much
too long to write. Let's break this into a bunch of smaller threads so
we don't have to read so much with any replies.
Willie
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