The multicast Designated Router (DR) must be configured to filter the Internet Group Management Protocol (IGMP) and Multicast Listener Discovery (MLD) Report messages to allow hosts to join a multicast group only from sources that have been approved by the organization.
Overview
Finding ID
Version
Rule ID
IA Controls
Severity
V-207169
SRG-NET-000364-RTR-000115
SV-207169r856653_rule
Medium
Description
Real-time multicast traffic can entail multiple large flows of data. Large unicast flows tend to be fairly isolated (i.e., someone doing a file download 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.
Review the configuration of the DR to verify that it is filtering IGMP or MLD report messages, allowing hosts to only join multicast groups from sources that have been approved.
Note: This requirement is only applicable to Source Specific Multicast (SSM) implementation
If the DR is not filtering IGMP or MLD report messages, this is a finding.
Fix Text (F-7430r382536_fix)
Configure the DR to filter the IGMP and MLD report messages to allow hosts to join only those multicast groups from sources that have been approved.