3Com Switch 8800 Family Configuration Guide

Troubleshooting IGMP Snooping 429
■ If IGMP Snooping is not enabled, carry out the igmp-snooping enable
command in system view to enable IGMP Snooping. Then, use the same
command in VLAN view to enable IGMP Snooping in the corresponding VLAN.
2 Multicast forwarding table set up by IGMP Snooping is incorrect.
■ Carry out the display igmp-snooping group command in any view to display
if the multicast group is the expected one.
■ If the multicast group created by IGMP Snooping is not correct, turn to
professional maintenance personnel for help.
■ Continue with diagnosis 3 if the second step is completed.
3 Multicast forwarding table set up on the bottom layer is incorrect.
■ In any view, carry out the display mac-address vlan command to check
whether the MAC multicast forwarding table established in the bottom layer
by vlan-id is consistent with that established by IGMP Snooping.
■ If they are not consistent, please contact the maintenance personnel for help.