From: Bastien Roucariès Date: Sun, 12 Apr 2020 23:50:33 +0000 (+0200) Subject: Better documentation of mcast_to_unicast option X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=706f7d35e2cb9cdc935db3b7785b305029ffd736;p=mirror_iproute2.git Better documentation of mcast_to_unicast option This option is useful for Wifi bridge but need some tweak. Document it from kernel patches documentation Signed-off-by: Bastien Roucariès Signed-off-by: Stephen Hemminger --- diff --git a/man/man8/bridge.8 b/man/man8/bridge.8 index b9bd6bc5..ff6f6f37 100644 --- a/man/man8/bridge.8 +++ b/man/man8/bridge.8 @@ -383,6 +383,32 @@ there is no MDB entry. By default this flag is on. Controls whether a given port will replicate packets using unicast instead of multicast. By default this flag is off. +This is done by copying the packet per host and +changing the multicast destination MAC to a unicast one accordingly. + +.BR mcast_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. IGMP/MLD report suppression issue is usually +overcome by the network daemon (supplicant) 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 (see +.B hairpin +option). +Hairpin mode is performed after multicast snooping, therefore leading to +only deliver reports to STAs running a multicast router. + .TP .BR "neigh_suppress on " or " neigh_suppress off " Controls whether neigh discovery (arp and nd) proxy and suppression is