man: bridge: document per-port mcast_router settings

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

diff --git a/man/man8/bridge.8 b/man/man8/bridge.8
index 93852ed8227742e6fe515f4a78936dfb4435683c..2fa4f3d6966fa71c79facf42ef28daa05816e29b 100644 (file)
--- a/man/man8/bridge.8
+++ b/man/man8/bridge.8
@@ -47,6 +47,8 @@ bridge \- show / manipulate bridge addresses and devices
 .BR hwmode " { " vepa " | " veb " } ] [ "
 .BR bcast_flood " { " on " | " off " } ] [ "
 .BR mcast_flood " { " on " | " off " } ] [ "
+.BR mcast_router
+.IR MULTICAST_ROUTER " ] ["
 .BR mcast_to_unicast " { " on " | " off " } ] [ "
 .BR neigh_suppress " { " on " | " off " } ] [ "
 .BR vlan_tunnel " { " on " | " off " } ] [ "
@@ -473,6 +475,19 @@ By default this flag is on.
 Controls whether multicast traffic for which there is no MDB entry will be
 flooded towards this given port. By default this flag is on.
 
+.TP
+.BI mcast_router " MULTICAST_ROUTER "
+This flag is almost the same as the per-VLAN flag, see below, except its
+value can only be set in the range 0-2.  The default is
+.B 1
+where the bridge figures out automatically where an IGMP/MLD querier,
+MRDISC capable device, or PIM router, is located.  Setting this flag to
+.B 2
+is useful in cases where the multicast router does not indicate its
+presence in any meaningful way (e.g. older versions of SMCRoute, or
+mrouted), or when there is a need for forwarding both known and unknown
+IP multicast to a secondary/backup router.
+
 .TP
 .BR "mcast_to_unicast on " or " mcast_to_unicast off "
 Controls whether a given port will replicate packets using unicast