Repository : ssh://git@diktynna/doc On branches: backup-redmine,main

commit 9847f8cd001e62a58f31bbbfdfedb712d078bb3d Author: Linus Lüssing linus.luessing@c0d3.blue Date: Fri Apr 19 20:59:53 2024 +0000

doc: batman-adv/Multicast-IGMP-MLD-Report-Forwarding

9847f8cd001e62a58f31bbbfdfedb712d078bb3d batman-adv/Multicast-IGMP-MLD-Report-Forwarding.textile | 10 ++++++++++ 1 file changed, 10 insertions(+)

diff --git a/batman-adv/Multicast-IGMP-MLD-Report-Forwarding.textile b/batman-adv/Multicast-IGMP-MLD-Report-Forwarding.textile index 96e1e01b..a8c437f7 100644 --- a/batman-adv/Multicast-IGMP-MLD-Report-Forwarding.textile +++ b/batman-adv/Multicast-IGMP-MLD-Report-Forwarding.textile @@ -86,6 +86,16 @@ Answer: **no!**

!mld-to-mcast-routers-only-scenario-C.png!

+Learning: + +1) Bridged-in host A listens to a link-local multicast address <MC-LL-A> +2) Node Y floods an MLD Query through the mesh +3) Host A replies to the MLD query with an MLD Report for <MC-LL-A> +3.1) br0 on node X learns that a listener for <MC-LL-A> is behind eth0 and then forwards the MLD Report further towards the querier on bat0, as required by RFC4541 +3.2) batman-adv on node X learns about the listener for <MC-LL-A> through the export of the bridge and then adds it to TT, which gets distributed to other nodes. +3.3) With the batman-adv multicast_rtr_only option enabled bat0 on node X will not forward the MLD Report +3.4) batman-adv on nodes Y learns about <MC-LL-A> through the TT + Potential Workarounds:

A) Set bridge port _multicast_router_ setting for bat0 to 2 (e.g.: _$ echo 2 > /sys/class/net/bat0/brport/multicast_router_) => always forwards multicast packets to bat0