Samsung phones block WiFi IPv6 when sleeping, delayed notifications
tore at fud.no
Wed Jun 10 14:45:45 CEST 2015
* Lorenzo Colitti
> 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.
AIUI, the maximum RA Lifetime is 9000 seconds. RFC 4861, section 6.2.1.
So unless you're a polyphasic sleeper, the handset will loose
connectivity overnight no matter what...
> 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.
Frequent unsolicited RAs was how I worked around the above problem.
While my phone would loose connectivity while on my nightstand, at
least with frequent RAs the IPv6 connectivity would recover quickly
once I started using my phone again in the morning. With infrequent
RAs, it would stay broken for a very long time.
But this was a few years ago, so maybe the situation has improved since
then? I imagine the handset could get away with not listening to RAs
while in sleep mode if it did send an RS some time before any of the
information learned from RAs was about to expire, for example.
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