V-269858

Discussion

PIM is a routing protocol used to build multicast distribution trees for forwarding multicast traffic across the network infrastructure. PIM traffic must be limited to only known PIM neighbors by configuring and binding a PIM neighbor filter to those interfaces that have PIM enabled. If a PIM neighbor filter is not applied to those interfaces that have PIM enabled, unauthorized routers can join the PIM domain, discover and use the rendezvous points, and also advertise their rendezvous points into the domain. This can result in a denial of service by traffic flooding or result in the unauthorized transfer of data.

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This requirement is not applicable for the DODIN Backbone.

Review the multicast topology diagram and determine if router interfaces are enabled for IPv4 or IPv6 multicast routing.

If the router is enabled for multicast routing, verify all interfaces enabled for PIM have a neighbor filter bound to the interface. The neighbor filter must only accept PIM control plane traffic from the documented PIM neighbors.

Step 1: Verify that a PIM neighbor filter has been configured.

!
ip access-list PIM_NBR_FILTER
 seq 10 permit ip 10.10.10.2/32 any
 
Step 2: Verify all interfaces enabled for PIM have the neighbor filter bound to the interface.

!
interface vlan100
 no shutdown
 ip pim sparse-mode
 ip pim neighbor-filter PIM_NBR_FILTER

If PIM neighbor filters are not bound to all interfaces that have PIM enabled, this is a finding.