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

commit f0e288b82cbc4abbb8a9d14318dccf96eee08c91 Author: Linus Lüssing linus.luessing@c0d3.blue Date: Fri Apr 19 20:42:08 2024 +0000

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

f0e288b82cbc4abbb8a9d14318dccf96eee08c91 .../Multicast-IGMP-MLD-Report-Forwarding.textile | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+)

diff --git a/batman-adv/Multicast-IGMP-MLD-Report-Forwarding.textile b/batman-adv/Multicast-IGMP-MLD-Report-Forwarding.textile index 1fbae8dd..590d7f0a 100644 --- a/batman-adv/Multicast-IGMP-MLD-Report-Forwarding.textile +++ b/batman-adv/Multicast-IGMP-MLD-Report-Forwarding.textile @@ -24,6 +24,24 @@ Answer: yes

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

+**Learning:** + +1) Bridged-in host B listens to a link-local multicast address <MC-LL-B> +2) Node Z floods an MLD Query through the mesh +3) Host B replies to the MLD query with an MLD Report for <MC-LL-B> +3.1) br0 on node Y learns that a listener for <MC-LL-B> 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 Y learns about the listener for <MC-LL-B> 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 batman-adv will refrain to forward the MLD Report further into the mesh +3.4) batman-adv on nodes X and Z learn about <MC-LL-B> through the TT + +**Multicast packet forwarding:** + +4) Bridged-in host A sends a multicast packet to the multicast address <MC-LL-B> +4.1) br0 on node X has not heard of <MC-LL-B>, but will forward the multicast packet towards the MLD Querier, as required by RFC4541 +4.2) batman-adv on node X had previously learned through the TT that <MC-LL-B> has a listener on node Y and batman-adv will therefore forward the multicast packet to node Y +4.3) br0 on node Y has previously learned about <MC-LL-B> through the MLD Report, so it forwards the multicast packet on eth0 to host B +4.4) host B successfully receives the multicast packet! + h3. Scenario B: Multicast to host on node with a querier

h4. Scenario B, Overview: