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

commit b30aa3a65893c5132388faa3ac05134eecd0b279 Author: Linus Lüssing linus.luessing@c0d3.blue Date: Sat Aug 31 20:55:27 2024 +0000

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

b30aa3a65893c5132388faa3ac05134eecd0b279 .../Multicast-IGMP-MLD-Report-Forwarding.textile | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/batman-adv/Multicast-IGMP-MLD-Report-Forwarding.textile b/batman-adv/Multicast-IGMP-MLD-Report-Forwarding.textile index 3d6074e0..3ea88cec 100644 --- a/batman-adv/Multicast-IGMP-MLD-Report-Forwarding.textile +++ b/batman-adv/Multicast-IGMP-MLD-Report-Forwarding.textile @@ -129,7 +129,23 @@ Answer: yes

**Learning:**

-WIP +1) Bridged-in host A listens to a link-local multicast address <MC-LL-A> +2) Bridged-in host C on node Y floods an MLD Query through the mesh +2.1) Node Y sets and floods a WANT_ALL flag, because querier is potentially [[Multicast-optimizations-flags#Case-3-Shadowing-Multicast-Querier|"shadowing"]]. +2.2) Node X learns node Y's WANT_ALL flag. +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) batman-adv on node X will forward the MLD Report towards node Y, even with the multicast_rtr_only option enabled, as node Y has the WANT_ALL flag set. +3.4) batman-adv on node Y learns about <MC-LL-A> through the TT +3.5) br0 on node Y learns that a listener for <MC-LL-A> is behind bat0 and then forwards the MLD Report further towards the querier on eth0, as required by RFC4541 + +**Multicast packet forwarding:** + +4) Bridged-in host B sends a multicast packet to the multicast address <MC-LL-A> +4.1) br0 on node X has heard of <MC-LL-B> and will forward the multicast packet towards bat0, as required by RFC4541 +... +Packet arrives at bridged-in host A

h3. Scenario E: Multicast to host on node with a bridged-in querier