[josm-dev] IPv6 problems

[Florian Lohoff]

On Thu, Dec 31, 2015 at 11:09:24PM +0100, Dirk Stöcker wrote:
> >JOSM is a pain in the ass concerning ipv6. I typically roam with my
> >notebook between dualstack and ipv4 only locations with suspend/resume
> >and most of the time i need to save session restart josm etc.
> >Its not even deterministic what the error looks like it just
> >complains on some random network access ...
> 
> If you switch between such networks disable IPv6 with "prefer.ipv6"
> set to "false" or use a start script to set correct settings.

But this is simply a broken advise - We want ipv6 and all RFCs
have been written with transition in mind. You are now telling
here is this app called JOSM and whenever you are on ipv6 turn
it off because it might cause problems.

This is exactly what the authors of all the RFCs tried to prevent.
You are now causing a bad reputation on ipv6 although
the application is simply not constructed with the Best Common
Practices.

> There are too few users with that specific issue to care for them
> right now with an automatic approach.

Germany - Bigges Community - Largest ISP Telekom is switching all
DSL contracts to Dualstack. Kabel Deutschland is already handing
out IPv6 be default with DS Light. So within a very short timeframe
you'll see a lot more people complaining.

> Java does not support on-the-fly detection, but this setting must be
> done before first network usage and cannot be changed later. We
> can't change that behaviour. Feel free to submit a Java bug report.

There is no such thing as a on-the-fly detection. You as the application
author need to write the detection. You need robust "connect" logic
which tries ipv6 and falls back to ipv4 when the connect does not
work. The latest RFCs gives even more advice on how to work around
long delays induced by servers advertising ipv6 and not responding
to it or intermitted ipv6 problems e.g. packet loss in the v6 path. This
is the daily business for an ISP - You path are different for v4 than
for v6 so you have different latencys, paths, packet loss probabilities
etc.

> We also do not fallback to secondary IPV4 addresses and so on and so
> on. Happy Eyeballs is a feature and we don't have that feature.

Happy Eyeballs is the continuation of fallback logic refinement.

> Don't know where you find the statement in the RFC above. Problems
> in section 3 of the document still have to be fixed, the document
> itself provides only a workaround to "enjoy nearly identical
> performance" even without fixing the problems. Time advanced since
> 1994 where the first statement from section 3 comes and also since
> 2012 where the RFC was written. I see no sense in spending lots of
> work on fixing broken user setups. If you can convince Java to
> support IPv6 better and switching during runtime, we'll use it.
> Otherwise we expect users to use proper networks settings.

My user setup is continously broken and i work around it. YOU refuse
to even implement 20 year old Best Common Practices written in RFCs
for a good reason.

Just as one of the examples 

http://comments.gmane.org/gmane.comp.gis.openstreetmap.region.de/110207

So please - either fix ipv6 in JOSM by implementing the BCPs or
drop the ipv6 support completely - Currently you are breaking tons
of user setups and you actively blame ipv6 for it. 

> For me the main problem are ISP's which provide broken or no IPv6
> connectivity.

Sorry - NO - I have a perfectly working ipv6 setup with German Telekom
at home. Even there i need workarounds with josm not falling back
to ipv4 with the tracer plugin.

Then i suspend, drive to work, resume and my setup is broken because
i dont have ipv6 at work but josm caches it knowledge which it shouldnt.

JOSM tries to be very clever and tries to detect if it has
IPv6 connectivity and caches the knowledge. THIS IS BROKEN ALREADY.
EVERY single connection needs the fallback logic for itself without
cached prior knowledge of the environment.

With mobility my ipv4 only connection can change to dualstack to dslight 
to a pure ipv6 with 6to4 NAT back to ipv4. If my services are reachable
Dualstack there should be service everywhere. With JOSM the first
change in network environment needs an application restart.

This is 80ies - "You have moved your mouse - please reboot"

Flo
-- 
Florian Lohoff                                                 f at zz.de
      We need to self-defend - GnuPG/PGP enable your email today!
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 828 bytes
Desc: Digital signature
URL: <http://lists.openstreetmap.org/pipermail/josm-dev/attachments/20160101/f0535592/attachment-0001.sig>