Felix Fietkau
2017-Jan-10 21:27 UTC
[Bridge] [PATCH net-next] bridge: multicast to unicast
On 2017-01-10 11:56, Johannes Berg wrote:> On Tue, 2017-01-10 at 05:18 +0100, Linus L?ssing 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
IgorMitsyanko
2017-Jan-11 11:26 UTC
[Bridge] [PATCH net-next] bridge: multicast to unicast
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 L?ssing 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? 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?
Felix Fietkau
2017-Jan-11 11:30 UTC
[Bridge] [PATCH net-next] bridge: multicast to unicast
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 L?ssing 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? - Felix