Samsung phones block WiFi IPv6 when sleeping, delayed notifications

[Lorenzo Colitti]

John,

are *all* IPv6 packets blocked, or just multicast packets? I know that a
number of devices will drop multicast IPv6 packets. This eventually
blackholes connections because the device stops receiving RAs and thus
loses its default route, but that can be worked around by setting long
timers in the RA. I wasn't aware of devices dropping all inbound IPv6
packets, that really seems like a bad bug.

FWIW, if you need an existence proof that it's possible to make this work,
recent Nexus device should not have either problem. Feel free to ask
Samsung to get in touch with me if they want to know how it works on Nexus.

A network that is configured to send RAs every 15 seconds will have a
devastating effect on battery life, and such networks are part of the
reason that manufacturers drop all multicast packets during sleep. Please
don't do that. Nexus devices rate-limit RAs in firmware in order to survive
on such aggressive networks, but that's not perfect.

Cheers,
Lorenzo

On Wed, Jun 10, 2015 at 2:33 PM, John Mann <john.mann at monash.edu> wrote:

> Hi,
>
> We have noticed that Samsung Android phones and tablets on dual-stack
> IPv4/IPv6 WiFi experience delayed Google notifications when the screen is
> off.
> This issue is blocking the enabling of IPv6 across our large campus WiFi
> network.
>
> Has anyone else experienced this behaviour and escalated this to Samsung,
> or found a fix?
>
> Our Samsung liaison person today said
> ===
>
> ---
>
> IPv6 packets are getting filtered due to the current consumption issue
> while device is in sleep mode.
>
>
>
> *IPv6 Concept of Samsung models:*
>
>
>
> When device enters the sleep mode, current implementation is that all the
> IPv6 packets from AP are getting blocked. All IPv4 and IPv6 packets are
> received while the LCD is on, however LCD off will be in blocked mode.
>
> This is because some of the current AP in markets introduces unnecessary
> IPv6 Multicast packets, which in turn wake up the devices which are in
> sleep mode, causing the issue of increase in the current consumption.
>
> Therefore a feature is applied on WiFi driver to filter off all IPv6 packets
> while in sleep mode.
>
> ---
>
>
>
> I have requested , How to activate that filter on for all IPv6 packets
> even when device at sleep mode. So far, it seems like it’s a permanent
> implementation and filter is not customizable for configuration.
> ===
>
>
> This problem has been raised before.  See
>     http://commandline.ninja/2014/01/02/samsung-galaxy-s4-ipv6-borked/
>
>
> http://developer.samsung.com/forum/board/thread/view.do?boardName=General&messageId=239890
> ---
> Hi, this is a serious bug in the WIFI driver of several Samsung Android
> phones, which prevents IPv6 enabled WLAN networks to work correctly. The
> phone is almost unuseable (while in standby mode) if it is part of a IPv6
> enabled wireless, because the lower level link protocol misses to update
> routing information and neighbourhood discovery.
> ...
>
> *This is really a serious IPv6 problem on the broadcom-wifi samsung phones
> that should be solved by a coming firmware update for the wifi radio
> firmware or kernel driver. In the current state, Samsung phones with that
> problem cannot be used in IPv6 enabled wifi networks - and you have no
> chance to disable IPv6 on the phone!!!*
> ---
> developers.samsung , Jul 31, 2013 08:46
> Hello,
>
> Blocking packets of IPv6 when screen is off is intended because battery
> runs down rapidly due to increasing standby power.
>
> End-users can connect to networks continually by IPv4.
>
> Best Regards,
> Samsung Developers
> ---
>
> See also
>    https://code.google.com/p/android/issues/detail?id=32662
>
> Thanks,
>     John
>
>
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