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.
An XCCDF Rule
Description
<VulnDiscussion>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 (224.0.1.39 and 224.0.1.40). 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.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>
- ID
- SV-221145r999754_rule
- Severity
- Low
- References
- Updated
Remediation - Manual Procedure
Configure the switch with an export policy to 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 prefix-list OUTBOUND_MSDP_SA_FILTER seq 10 deny 10.0.0.0/8 le 32
SW1(config)# ip prefix-list OUTBOUND_MSDP_SA_FILTER seq 20 permit 0.0.0.0/0 ge 8
SW1(config)# exit
SW1(config)# ip msdp sa-policy x.1.28.2 prefix-list OUTBOUND_MSDP_SA_FILTER out