V-254050

Discussion

Real-time multicast traffic can entail multiple large flows of data. Large unicast flows tend to be fairly isolated (i.e., someone downloading a file here or there), whereas multicast can have broader impact on bandwidth consumption, resulting in extreme network congestion. Hence, it is imperative that there is multicast admission control to restrict which multicast groups hosts are allowed to join via IGMP or MLD.

Check Content

Review the configuration of the DR to verify that it is filtering IGMP or MLD report messages, allowing hosts to join only those groups that have been approved.

Note: This requirement is only applicable to Source Specific Multicast (SSM) implementation. This requirement is not applicable to Any Source Multicast (ASM) since the filtering is being performed by the Rendezvous Point router.

[edit policy-options]
policy-statement <name> {
    term unauth-groups {
        from {
            route-filter 224.0.1.2/32 exact;
            route-filter 224.0.2.2/32 exact;
        }
        then reject;
    }
    term allow-others {
        then accept;
    }
}
policy-statement <name IPv6> {
    term unauth-groups {
        from {
            route-filter fec0:1:1:4::/64 exact;
        }
        then reject;
    }
    term allow-others {
        then accept;
    }
}

[edit protocols]
igmp {
    interface <name>.<logical unit> {
        group-policy <policy name>;
    }
}
mld {
    interface <name>.<logical unit> {
        group-policy <policy name IPv6>;
    }
}

If the DR is not filtering IGMP or MLD report messages, this is a finding.