Operation Manual – MulticastH3C S7500 Series Ethernet Switches Chapter 3 IGMP Snooping Configuration3-15[H3C-vlan1024] multicast-vlan enable[H3C-vlan1024] quit[H3C] multicast-vlan 1024 subvlan 2 to 73.5 Troubleshooting IGMP SnoopingSymptom: Multicast does not work on the switch.Solution:The reason may be:1) IGMP Snooping is not enabled.z Use the display current-configuration command to check the status of IGMPSnooping.z If IGMP Snooping is disabled, check whether it is disabled globally or in thecorresponding VLAN. If it is disabled globally, use the igmp-snooping enablecommand in both system view and VLAN view to enable it both globally and in thecorresponding VLAN at the same time. If it is only disabled in the correspondingVLAN, use the igmp-snooping enable command in VLAN view only to enable itin the corresponding VLAN.2) Multicast forwarding tables set up by IGMP Snooping are wrong.z Use the display igmp-snooping group command to check if the multicast groupsare expected ones.z If the multicast group set up by IGMP Snooping is not correct, contact yourtechnical support personnel.z Continue with solution 3) if the second step does not work.If it is not the reason, the possible reason may be:3) MAC multicast forwarding tables set up by IGMP Snooping are wrong.z Use the display mac-address vlan command to check whether the MACmulticast forwarding table set up in the VLAN view identified by the vlan-idargument is consistent with the one set up by IGMP Snooping.z If they are not consistent, contact your technical support personnel.
