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The Cisco Multicast Source Discovery Protocol (MSDP) switch must be configured to filter source-active multicast advertisements to external MSDP peers to avoid global visibility of local-only multicast sources and groups.


Finding ID Version Rule ID IA Controls Severity
V-221067 CISC-RT-000930 SV-221067r622190_rule Low
To avoid global visibility of local information, there are a number of source-group (S, G) states in a PIM-SM domain that must not be leaked to another domain, such as multicast sources with private address, administratively scoped multicast addresses, and the auto-RP groups ( and Allowing a multicast distribution tree, local to the core, to extend beyond its boundary could enable local multicast traffic to leak into other autonomous systems and customer networks.
Cisco IOS XE Switch RTR Security Technical Implementation Guide 2023-09-13


Check Text ( C-22782r408995_chk )
Review the switch configuration to determine if there is export policy to block local source-active multicast advertisements.

Step 1: Verify that an outbound source-active filter is bound to each MSDP peer as shown in the example below:

ip msdp peer remote-as 8
ip msdp sa-filter out list OUTBOUND_MSDP_SA_FILTER

Step 2: Review the access lists referenced by the source-active filters and verify that MSDP source-active messages being sent to MSDP peers do not leak advertisements that are local.

ip access-list extended OUTBOUND_MSDP_SA_FILTER
deny ip any
permit ip any any

If the switch is not configured with an export policy to filter local source-active multicast advertisements, this is a finding.
Fix Text (F-22771r408996_fix)
Configure the switch with an export policy avoid global visibility of local multicast (S, G) states. The example below will prevent exporting multicast active sources belonging to the private network.

SW1(config)#ip access-list extended OUTBOUND_MSDP_SA_FILTER
SW1(config-ext-nacl)#deny ip any
SW1(config-ext-nacl)#permit ip any any
SW1(config)#ip msdp sa-filter in x.1.28.2 list OUTBOUND_MSDP_SA_FILTER