Detections
Analytics
3.3.7 Multicast Boundary ACL
Information
A multicast boundary ACL (Access Control List) is a configuration mechanism that filters multicast traffic at specified interfaces to control the routing of multicast packets. This feature works on Point-to-Point links, including ROP/L3 LAG or Point-to-Point SVI, and can manage both multicast data and control packets, such as IGMP joins and PIM join/prune messages. The ACL rules can match multicast group entries (*,G) and use subnet masks to define address ranges, supporting IP, IGMP, and PIM protocols. While MSDP (Multicast Source Discovery Protocol) continues to forward source announcements (SA messages) across boundaries regardless of ACL configurations, multicast boundary ACLs play a crucial role in defining which multicast traffic is permitted or denied between different domains. The feature is IPv4-specific and does not support Anycast RP with MSDP mesh groups across boundaries. For filtering PIM bootstrap messages, a separate pim bsr-boundary configuration is requiredThe primary rationale for implementing multicast boundary ACLs is to enforce traffic control and domain isolation in multicast-enabled networks. By filtering multicast traffic at the interface level, organizations can prevent unwanted or unauthorized multicast traffic from being routed across domains, which helps maintain network security and stability. The ability to match specific group addresses, such as the example where traffic for 239.0.0.0/8 is denied while 224.0.0.0/4 is permitted, gives network administrators granular control over traffic policies. This control is critical in preventing multicast routing loops, managing traffic congestion, and ensuring that only necessary multicast traffic flows between domains.
NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.
Solution
The boundary ACL example shown below creates a boundary where group address in 239.0.0.0/8 is denied and all other group addresses in 224.0.0.0/4 are permitted. Since the source address is any, it matches (*,G) traffic. The boundary will be applied in both in and outbound directions.access-list ip bound
10 deny any any 239.0.0.0/255.0.0.0
20 permit any any 224.0.0.0/240.0.0.0
interface lag 1
ip address 40.1.1.1/24
ip pim-sparse enable
ip multicast boundary access-list bound
Impact:
Configuring multicast boundary ACLs has a significant impact on network performance, security, and traffic management. By applying filters in both inbound and outbound directions, the feature ensures that only authorized multicast traffic crosses domain boundaries, reducing the likelihood of network overload or disruptions caused by excessive or misrouted multicast packets. It also enhances security by isolating multicast domains, preventing unauthorized traffic from infiltrating sensitive areas of the network.
See Also
Item Details
Category: ACCESS CONTROL, MEDIA PROTECTION
References: 800-53|AC-3, 800-53|AC-5, 800-53|AC-6, 800-53|MP-2, CSCv7|14.6
Plugin: ArubaOS
Control ID: 5ccd5e0e16b8974fc217b0e8e33a0035dab46ba819c27937d10a58cf6393087a