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Date:   Wed, 3 Apr 2019 11:53:33 -0700
From:   Stephen Hemminger <>
Subject: Fw: [Bug 203137] New: Bridge does not forward multicast if
 multicast_querier is enabled

Begin forwarded message:

Date: Wed, 03 Apr 2019 04:49:49 +0000
Subject: [Bug 203137] New: Bridge does not forward multicast if multicast_querier is enabled

            Bug ID: 203137
           Summary: Bridge does not forward multicast if multicast_querier
                    is enabled
           Product: Networking
           Version: 2.5
    Kernel Version: 5.0.3
          Hardware: All
                OS: Linux
              Tree: Fedora
            Status: NEW
          Severity: normal
          Priority: P1
         Component: Other
        Regression: Yes

When multicast querier is enabled on a bridge, multicasts are not forwarded
according to the multicast forwarding database.

"bridge mdb" shows the multicast forwarding entries but they are not forwarded
to the ports.
Manually adding the port to the bridge multicast DB works.

Wireshark shows the packets arriving on the bridge but not being sent out the
proper port.

The regression was introduced by commit
19e3a9c90c53479fecaa02307bf2db5ab8b3ffe3, "net: bridge: convert multicast to
generic rhashtable" by Nikolay Aleksandrov <>.

Steps to reproduce:

ip link add br0 type bridge mcast_querier 1
ip link set br0 up

ip link add v2 type veth peer name v3
ip link set v2 master br0
ip link set v2 up
ip link set v3 up
ip addr add dev v3

ip netns add test
ip link add v1 type veth peer name v1 netns test
ip link set v1 master br0
ip link set v1 up
ip -n test link set v1 up
ip -n test addr add dev v1

# Multicast receiver
ip netns exec test socat
UDP4-RECVFROM:5588,ip-add-membership=,fork -

# Multicast sender
echo hello | nc -u -s 5588

Observe that 'bridge mdb' has an entry for on port v1.
Observe that the multicast packets are seen on v2, v3 and br0 but not v1.

You are receiving this mail because:
You are the assignee for the bug.

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