[OpenWrt-Devel] About IGMP snooping support

[hayate]

My router hardware has a AR8327 switch which is supposed to support
hardware IGMP snooping, but it seems it doesn't work on my OpenWrt of trunk.

I noted that in target/linux/generic/files/drivers/net/phy/ar8216.h there
is a AR8327_FWD_CTRL1_IGMP defined but not used anywhere.

And there is a config option CONFIG_BRIDGE_IGMP_SNOOPING in kernel config.

Does these two affect this feature? How can I enable IGMP snooping in
OpenWrt on my router

Thanks

[Jonas Gorski]

Hi,

My router hardware has a AR8327 switch which is supposed to support hardware
IGMP snooping, but it seems it doesn't work on my OpenWrt of trunk.
I noted that in target/linux/generic/files/drivers/net/phy/ar8216.h there is
a AR8327_FWD_CTRL1_IGMP defined but not used anywhere.
And there is a config option CONFIG_BRIDGE_IGMP_SNOOPING in kernel config.
Does these two affect this feature? How can I enable IGMP snooping in
OpenWrt on my router

IGMP snooping for switches has a slightly different meaning than IGMP
snooing support in linux.
For switches (also for AR8xxx) IGMP snooping means that any
JOINS/LEAVES are redirected to the CPU port, so the CPU can
setup/update the appropriate forwarding entries in the switch.
So for this feature to work it requires a daemon capable of that,
which currently doesn't exist.

The IGMP snooping from linux does something like that already, but
only for bridge interface members. That means that is able to prevent
multicast traffic from leaking to wlan, but it does not have any
influence to the individual switch ports.

Jonas

[hayate]

Thank you Jonas,

If I understand correctly,
1. If that kind of daemons exist, it can prevent multicast flood in the
switch by setting proper rules
2. We can infer that if two switches are connected together, unless both of
them support IGMP snooping, at least one of them would suffer multicast
flood

right?

Post by hayate
Hi,

Post by hayate
My router hardware has a AR8327 switch which is supposed to support

hardware

Post by hayate
IGMP snooping, but it seems it doesn't work on my OpenWrt of trunk.
I noted that in target/linux/generic/files/drivers/net/phy/ar8216.h

there is

Post by hayate
a AR8327_FWD_CTRL1_IGMP defined but not used anywhere.
And there is a config option CONFIG_BRIDGE_IGMP_SNOOPING in kernel

config.

Post by hayate
Does these two affect this feature? How can I enable IGMP snooping in
OpenWrt on my router

IGMP snooping for switches has a slightly different meaning than IGMP
snooing support in linux.
For switches (also for AR8xxx) IGMP snooping means that any
JOINS/LEAVES are redirected to the CPU port, so the CPU can
setup/update the appropriate forwarding entries in the switch.
So for this feature to work it requires a daemon capable of that,
which currently doesn't exist.
The IGMP snooping from linux does something like that already, but
only for bridge interface members. That means that is able to prevent
multicast traffic from leaking to wlan, but it does not have any
influence to the individual switch ports.
Jonas
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...

[Jonas Gorski]

Post by hayate
Thank you Jonas,
If I understand correctly,
1. If that kind of daemons exist, it can prevent multicast flood in the
switch by setting proper rules
2. We can infer that if two switches are connected together, unless both of
them support IGMP snooping, at least one of them would suffer multicast
flood
right?

Yes, and yes. Also please don't top post.


Jonas