From be24eab05d664ff63d1216498e5f2e6986ccafc7 Mon Sep 17 00:00:00 2001 From: Ido Schimmel Date: Tue, 21 Mar 2023 15:01:27 +0200 Subject: bridge: mdb: Document the catchall MDB entries Document the catchall MDB entries used to transmit IPv4 and IPv6 unregistered multicast packets. In deployments where inter-subnet multicast forwarding is used, not all the VTEPs in a tenant domain are members in all the broadcast domains. It is therefore advantageous to transmit BULL (broadcast, unknown unicast and link-local multicast) and unregistered IP multicast traffic on different tunnels. If the same tunnel was used, a VTEP only interested in IP multicast traffic would also pull all the BULL traffic and drop it as it is not a member in the originating broadcast domain [1]. [1] https://datatracker.ietf.org/doc/html/draft-ietf-bess-evpn-irb-mcast#section-2.6 Signed-off-by: Ido Schimmel Reviewed-by: Nikolay Aleksandrov --- man/man8/bridge.8 | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/man/man8/bridge.8 b/man/man8/bridge.8 index 9753ce9e..4006ad23 100644 --- a/man/man8/bridge.8 +++ b/man/man8/bridge.8 @@ -1013,6 +1013,12 @@ device creation will be used. device name of the outgoing interface for the VXLAN device to reach the remote VXLAN tunnel endpoint. +.in -8 +The 0.0.0.0 and :: MDB entries are special catchall entries used to flood IPv4 +and IPv6 unregistered multicast packets, respectively. Therefore, when these +entries are programmed, the catchall 00:00:00:00:00:00 FDB entry will only +flood broadcast, unknown unicast and link-local multicast. + .in -8 .SS bridge mdb delete - delete a multicast group database entry This command removes an existing mdb entry. -- cgit v1.2.1