The value of vRtrIgmpGrpIfSapMaxGroups specifies the maximum number of
groups for which IGMP can have local receiver information based on
received IGMP reports on this SAP.
When this configuration is changed dynamically to a value lower than
currently accepted number of groups, the groups that are already
accepted are not deleted.
Only new groups will not be allowed. When this object has a value of 0,
there is no limit to the number of groups.