Let us imagine that as a matter of national policy we are all to live in smaller houses to save energy. In what respect would such a policy be realized if everyone bought a second, smaller house and started occupying both simultaneously?
The critical objective here is to create a situation where people can use the Internet successfully without requiring a full IPv4 address.
It is not going to be the case that anyone can use pure IPv6 100% of the time for several decades.
Getting people to use IPv6 is not an end in itself. If you have a full IPv4 address there is no point in using IPv6 in parallel.
Its like buying a Prius to show how ecological you are and towing it behind your Hummer.
The case where this dual stack is going to make sense is where the user has a shared IPv4 and clean IPv6 and there is a performance advantage to going through the clean connection.
This is not something that I would want to have to code for as an application programmer. I would want to have a call of the form 'get best connection for (protocol, domain_name) and have the platform figure it out using information that I would not want the application programmer to have access to.
<eom>
On Mon, Jan 24, 2011 at 7:02 AM, Mark Andrews <marka@xxxxxxx> wrote:
In message <201101241115.p0OBFPmU016916@xxxxxxxxxxxxxxxxxxx>, Martin Rex writes
:
> Brian E Carpenter wrote:The solution space is equally applicable to two IPv4 addresses or
> >
> > However, see draft-wing-v6ops-happy-eyeballs-ipv6
>
> Yuk. That approach appears to be from a completely different universe
> that solutions to the IPv4->IPv6 migration issue.
>
> Instead of solving the problem where it originates, at the network level,
> it dumps the entire problem onto the application in the worst conceivable
> fashion. It makes IPv6 and IPv4 worlds appear like two completely
> seperate and independent Internets, i.e. this proposal incurs on apps
> the exact same effort as migrating a completely different network protocol
> or completely different network.
two IPv6 addresses. You start one, wait a short while to see if
it succeeds then start another, etc. If the network is doing its
job you get a error back from it before you start the second and
you start it sooner. If it isn't then you don't waste 30 seconds
for the connect to timeout.
If you have a abnormally long path then you get some embryonic
connections. 500ms is more than enough time to wait for a terrestrial
path to complete. Sydney, Australia to Europe is high 3 hundreds
to low 4 hundreds of milliseconds.
% ~/a.out www.ripe.net
connect_to_host(www.ripe.net) -> 3 in 376 ms
%
I've seen plenty of people pick up one phone dial then put the call
> If anyone had suggested that for a migration from PSTN to VoiP, then
> everyone would have to use two phones these days, dial in parallel
> and hang up on whichever call establishes second.
on speaker then pick up a second phone and dial a different number
and put it on speaker when trying to reach someone with two numbers
urgently. They hang up which ever doesn't answer.
Having good error recovery at the application layer hasn't been a
> The problem that this draft tries to solve at the app-level really
> ought to be solved at the network level. Use IPv6 addresses that
> embed the alternative IPv4 address and have the network figure out
> whether the route is IPv6 clean and the connection can be established
> as IPv6 or only IPv4. (IPv4-NATing the IPv4 part of such an
> address along the way is probably "fun"...) ... for exactly those
> network interfaces that _have_ dual IPv4+IPv6 addresses.
issue until now because 99.99% of sites were single homed. This
is changing with almost a 100% of sites becoming multi-homed. It's
time the applications learned how to work well in such a environment.
It might also mean that one might be able to stop having to deploy
DNS servers that track reachability just to get some robustness
that should have been there if clients wern't using naive connection
strategies.
B.T.W. the a.out above implements this sort of connection strategy
with a 500 ms wait before attempting the second connection. The
wait for the 3rd connection is 250 ms, the 4th is 125 ms, the 5th
is 62 ms. You get the pattern. There are poll, select and thread
based versions.
Mark
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Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742 INTERNET: marka@xxxxxxx
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