[OpenWrt-Devel] [PATCHv3 openwrt 1/2] Revert "kernel: disable multicast-to-unicast translation for ipv6 neighbor solicitation (#17625)"

Linus Lüssing linus.luessing at c0d3.blue
Mon Aug 31 06:19:44 EDT 2015

On Mon, Aug 31, 2015 at 11:29:45AM +0200, Steven Barth wrote:
> >Ok, I was able to easily reproduce the issue here. Looking at the
> >tcpdump the wifi client receives its own Neighbor Solicitation
> >again, reflected through the bridge-hairpin option.
> Why are we reflecting packets back to the originator anyway? Could it not be excluded?

Currently the multicast-to-unicast patch reflects it back as it
detected that the originator itself is a listener of the multicast
group of the Neighbor Solicitation.

I had somehow expected that mac80211 would exclude it. But looks like it
doesn't. And yes, we can exclude/drop that unicast'ed multicast
packet with src==dst on the bridge side already like I said
before for a suggested fix. But it's not 100% sufficient yet, we'd
have issues again once a multicast router/querier is on an STA.

Cheers, Linus

> Btw. once we are bit more stable i will try to test how the igmpv3/mldv2 querier / proxy I wrote interacts here (disabling kernel querier).

I'd be interested to hear about that :).
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