Dell C9000 Series Networking Configuration Manual page 722

ip igmp access-group access-list-name
Dell Networking OS Behavior: Do not enter the ip igmp access-group command before creating the
access-list. If you do, after entering your first deny rule, the system clears multicast routing table and re-
learns all groups, even those not covered by the rules in the access-list, because there is an implicit deny all
rule at the end of all access-lists. Therefore, configuring an IGMP join request filter in this order might result in
data loss. If you must enter the ip igmp access-group command before creating the access-list, prevent
the system from clearing the routing table by entering a permit any rule with high sequence number before
you enter any other rules.
In the following example, virtual local area network (VLAN) 400 is configured with an access list to permit
only IGMP reports for group 239.0.0.1. Though Receiver 2 sends a membership report for groups 239.0.0.1
and 239.0.0.2, a multicast routing table entry is created only for group 239.0.0.1. VLAN 300 has no access list
Multicast Features 722