Re: [PATCH net-next] bridge: multicast to unicast

[IgorMitsyanko]

On 01/11/2017 02:30 PM, Felix Fietkau wrote:
> On 2017-01-11 12:26, IgorMitsyanko wrote:
> > On 01/11/2017 12:27 AM, Felix Fietkau wrote:
> > > On 2017-01-10 11:56, Johannes Berg wrote:
> > > > On Tue, 2017-01-10 at 05:18 +0100, Linus LÃssing wrote:
> > > > > On Mon, Jan 09, 2017 at 01:30:32PM -0800, Stephen Hemminger wrote:
> > > > > > I wonder if MAC80211 should be doing IGMP snooping and not bridge
> > > > > > in this environment.
> > > > > In the long term, yes. For now, not quite sure.
> > > > There's no "for now" in the kernel. Code added now will have to be
> > > > maintained essentially forever.
> > > I'm not sure that putting the IGMP snooping code in mac80211 is a good
> > > idea, that would be quite a bit of code duplication.
> > > This implementation works, it's very simple, and it's quite flexible for
> > > a number of use cases.
> > >
> > > Is there any remaining objection to merging this in principle (aside
> > > from potential issues with the code)?
> > >
> > > - Felix
> >
> > Hi Felix, can we consider two examples configurations with multicast
> > traffic:
> >
> > 1. AP is a source of multicast traffic itself, no bridge on AP. For
> > example, wireless video server streaming to several clients.
> > In this situation, we can not make use of possible advantages given by
> > mc-to-uc conversion?
> You could simply put the AP interface in a bridge, no need to have any
> other bridge members present.
>
> > 2. A configuration with AP + STA + 3 client devices behind STA.
> >                               ----|client 1|
> >                              |
> > |  mc  |----|AP|----|STA|---|---|client 2|
> > |server|                    |
> >                               ----|client 3|
> >
> > Multicast server behind AP streams MC video traffic. All 3 clients
> > behind the STA have joined the multicast group.
> > I'm not sure if this case will be handled correctly with mc-to-uc
> > conversion in bridge on AP?
> What do you mean by "3 client devices behind STA"? Are you using a
> 4-addr STA, multicast routing, or some kind of vendor specific "client
> bridge" hackery?

3 client devices connected by backbone Ethernet network. Generic
case is probably STA/AP operating in 4-addr mode (more or less standard
solution as far as I know).

"Client bridge" approach should not concern us here I think, it will
seem to AP and AP's bridge as a single client.

> - Felix