The value of vRtrIgmpIfMaxSources specifies the maximum number of sources
for which IGMP can have local receiver information based on received
IGMP reports on this interface. 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.