Comment 17 for bug 1653479

The issue is seen again on 3.1.3-81. The BUM tree was broken. We see the multicast manager is assigning label 0 to certain level 1 forwarder.

<level1_forwarders type="list" identifier="4">
                                        <list type="struct" size="2">
                                                <ShowMulticastForwarder>
                                                        <address type="string" identifier="1">172.23.10.202</address>
                                                        <label_block type="string" identifier="2">129477-129477</label_block>
                                                        <label type="u32" identifier="3">129477</label>
                                                        <router_id type="string" identifier="5">172.23.10.205</router_id>
                                                        <links type="list" identifier="4">
                                                                <list type="struct" size="0">
                                                                </list>
                                                        </links>
                                                </ShowMulticastForwarder>
                                                <ShowMulticastForwarder>
                                                        <address type="string" identifier="1">172.23.10.201</address>
                                                        <label_block type="string" identifier="2">129864-129864</label_block>
                                                        <label type="u32" identifier="3">0</label>
                                                        <router_id type="string" identifier="5">172.23.10.207</router_id>
                                                        <links type="list" identifier="4">
                                                                <list type="struct" size="0">
                                                                </list>
                                                        </links>
                                                </ShowMulticastForwarder>
                                        </list>
                                </level1_forwarders>
 <ShowMulticastForwarder>
                                                        <address type="string" identifier="1">172.23.10.201</address>
                                                        <label_block type="string" identifier="2">130225-130225</label_block>
                                                        <label type="u32" identifier="3">0</label>
                                                        <router_id type="string" identifier="5">172.23.10.207</router_id>
                                                        <links type="list" identifier="4">
                                                                <list type="struct" size="0">
                                                                </list>
                                                        </links>
                                                </ShowMulticastForwarder>

Logs and cores shared with Ananth.