Samsung phones block WiFi IPv6 when sleeping, delayed notifications

Lorenzo Colitti lorenzo at
Wed Jun 10 14:55:11 CEST 2015

On Wed, Jun 10, 2015 at 9:45 PM, Tore Anderson <tore at> wrote:

> > 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.

Except that 65535 works fine. :-)

> 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.

It depends on the wifi firmware. On Nexus devices, RAs are allowed through
by the firmware, but rate-limited.

(The rate-limiting is an unfortunate necessity when you have tens of
thousands of nodes on one network and your routers don't support replying
to solicited RAs with unicast packets and end up sending a multicast RAs at
the maximum allowed rate of 1 every 3 seconds.)
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