The value of vRtrIgmpGrpIfSapMaxSources specifies the maximum number of
sources per group 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 sources, the sources that are already
accepted are not deleted.
Only new sources will not be allowed. When this object has a value of 0,
there is no limit to the number of sources.