On 19/01/17 03:45, Linus Lüssing wrote: > From: Felix Fietkau <nbd@xxxxxxxx> > > Implements an optional, per bridge port flag and feature to deliver > multicast packets to any host on the according port via unicast > individually. This is done by copying the packet per host and > changing the multicast destination MAC to a unicast one accordingly. > > multicast-to-unicast works on top of the multicast snooping feature of > the bridge. Which means unicast copies are only delivered to hosts which > are interested in it and signalized this via IGMP/MLD reports > previously. > > This feature is intended for interface types which have a more reliable > and/or efficient way to deliver unicast packets than broadcast ones > (e.g. wifi). > > However, it should only be enabled on interfaces where no IGMPv2/MLDv1 > report suppression takes place. This feature is disabled by default. > > The initial patch and idea is from Felix Fietkau. > > Signed-off-by: Felix Fietkau <nbd@xxxxxxxx> > [linus.luessing@xxxxxxxxx: various bug + style fixes, commit message] > Signed-off-by: Linus Lüssing <linus.luessing@xxxxxxxxx> > > --- > > This feature is used and enabled by default in OpenWRT and LEDE for AP > interfaces for more than a year now to allow both a more robust multicast > delivery and multicast at higher rates (e.g. multicast streaming). > > In OpenWRT/LEDE the IGMP/MLD report suppression issue is overcome by > the network daemon enabling AP isolation and by that separating all STAs. > Delivery of STA-to-STA IP mulitcast is made possible again by > enabling and utilizing the bridge hairpin mode, which considers the > incoming port as a potential outgoing port, too. > > Hairpin-mode is performed after multicast snooping, therefore leading to > only deliver reports to STAs running a multicast router. > > Changes in v4: > * readd "From: Felix Fietkau [...]" (missed it again in v3) > > Changes in v3: > * fix an uninitialized variable bug introduced in br_multicast_flood() > in v2, found by kbuild test bot > > Changes in v2: > * netlink support (thanks Nik!) > * fixed switching between multicast_to_unicast on/off > -> even after toggling an already existing entry would > stale in its mode and would never be replaced > -> new extra check in br_port_group_equal) > * reduced checks in br_multicast_flood() from two to one > to address fast-path concerns (thanks Nik!) > * rev-christmas tree ordering (thanks Nik!) > * removed "net_bridge_port_group::unicast", using > ::flags instead (thanks Nik!) > * BR_MULTICAST_TO_UCAST -> BR_MULTICAST_TO_UNICAST > (BR_MULTICAST_FLAST_LEAVE has the same length anyway) > * simplified maybe_deliver_addr() > (no return, no "prev" paramater -> was a NOP anyway) > * added "From: Felix Fietkau [...]" > * added "Signed-off-by: Felix Fietkau [...]" > --- > include/linux/if_bridge.h | 1 + > include/uapi/linux/if_link.h | 1 + > net/bridge/br_forward.c | 37 ++++++++++++++++- > net/bridge/br_mdb.c | 2 +- > net/bridge/br_multicast.c | 96 ++++++++++++++++++++++++++++++++------------ > net/bridge/br_netlink.c | 5 +++ > net/bridge/br_private.h | 8 ++-- > net/bridge/br_sysfs_if.c | 2 + > 8 files changed, 121 insertions(+), 31 deletions(-) > Looks good to me, Reviewed-by: Nikolay Aleksandrov <nikolay@xxxxxxxxxxxxxxxxxxx>
