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XCCDF
Cisco IOS Switch RTR Security Technical Implementation Guide
SRG-NET-000362-RTR-000123
SRG-NET-000362-RTR-000123
An XCCDF Group - A logical subset of the XCCDF Benchmark
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SRG-NET-000362-RTR-000123
1 Rule
<GroupDescription></GroupDescription>
The Cisco multicast Designated switch (DR) must be configured to set the shortest-path tree (SPT) threshold to infinity to minimalize source-group (S, G) state within the multicast topology where Any Source Multicast (ASM) is deployed.
Medium Severity
<VulnDiscussion>ASM can have many sources for the same groups (many-to-many). For many receivers, the path via the RP may not be ideal compared with the shortest path from the source to the receiver. By default, the last-hop switch will initiate a switch from the shared tree to a source-specific SPT to obtain lower latencies. This is accomplished by the last-hop switch sending an (S, G) Protocol Independent Multicast (PIM) Join toward S (the source). When the last-hop switch begins to receive traffic for the group from the source via the SPT, it will send a PIM Prune message to the RP for the (S, G). The RP will then send a Prune message toward the source. The SPT switchover becomes a scaling issue for large multicast topologies that have many receivers and many sources for many groups because (S, G) entries require more memory than (*, G). Hence, it is imperative to minimize the amount of (S, G) state to be maintained by increasing the threshold that determines when the SPT switchover occurs.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>