Rule ID
SV-216635r1117236_rule
Version
V3R4
CCIs
The interoperability of BGP extensions for interdomain multicast routing and MSDP enables seamless connectivity of multicast domains between autonomous systems. MP-BGP advertises the unicast prefixes of the multicast sources used by Protocol Independent Multicast (PIM) routers to perform RPF checks and build multicast distribution trees. MSDP is a mechanism used to connect multiple PIM sparse-mode domains, allowing RPs from different domains to share information about active sources. When RPs in peering multicast domains hear about active sources, they can pass on that information to their local receivers, thereby allowing multicast data to be forwarded between the domains. Configuring an import policy to block multicast advertisements for reserved, Martian, single-source multicast, and any other undesirable multicast groups, as well as any source-group (S, G) states with Bogon source addresses, would assist in avoiding unwanted multicast traffic from traversing the core.
Review the router configuration to determine if there is import policy to block source-active multicast advertisements for any undesirable multicast groups, as well as any (S, G) states with undesirable source addresses. Step 1: Verify that an inbound source-active filter is bound to each MSDP peer. ip msdp peer x.1.28.2 remote-as 2 ip msdp sa-filter in x.1.28.2 list INBOUND_MSDP_SA_FILTER Step 2: Review the access lists referenced by the source-active filter to verify that undesirable multicast groups, auto-RP, single-source multicast (SSM) groups, and advertisements from undesirable sources are blocked. ip access-list extended INBOUND_MSDP_SA_FILTER deny ip any host 224.0.1.3 log deny ip any host 224.0.1.24 log deny ip any host 224.0.1.22 log deny ip any host 224.0.1.2 log deny ip any host 224.0.1.35 log deny ip any host 224.0.1.60 log deny ip any host 224.0.1.39 log deny ip any host 224.0.1.40 log deny ip any 232.0.0.0 0.255.255.255 log deny ip any 239.0.0.0 0.255.255.255 log deny ip 10.0.0.0 0.255.255.255 any log deny ip 127.0.0.0 0.255.255.255 any log deny ip 172.16.0.0 0.15.255.255 any log deny ip 192.168.0.0 0.0.255.255 any log permit ip any any log If the router is not configured with an import policy to filter undesirable SA multicast advertisements, this is a finding.
Configure the MSDP router to filter received source-active multicast advertisements for any undesirable multicast groups and sources as shown in the example below. R8(config)#ip access-list extended INBOUND_MSDP_SA_FILTER R8(config-ext-nacl)#deny ip any host 224.0.1.3 log ! Rwhod R8(config-ext-nacl)#deny ip any host 224.0.1.24 log ! Microsoft-ds R8(config-ext-nacl)#deny ip any host 224.0.1.22 log ! SVRLOC R8(config-ext-nacl)#deny ip any host 224.0.1.2 log ! SGI-Dogfight R8(config-ext-nacl)#deny ip any host 224.0.1.35 log ! SVRLOC-DA R8(config-ext-nacl)#deny ip any host 224.0.1.60 log ! hp-device-disc R8(config-ext-nacl)#deny ip any host 224.0.1.39 log ! Auto-RP R8(config-ext-nacl)#deny ip any host 224.0.1.40 log ! Auto-RP R8(config-ext-nacl)#deny ip any 232.0.0.0 0.255.255.255 log ! SSM range R8(config-ext-nacl)#deny ip any 239.0.0.0 0.255.255.255 log ! Admin scoped range R8(config-ext-nacl)#deny ip 10.0.0.0 0.255.255.255 any log ! RFC 1918 address range R8(config-ext-nacl)#deny ip 127.0.0.0 0.255.255.255 any log ! RFC 1918 address range R8(config-ext-nacl)#deny ip 172.16.0.0 0.15.255.255 any log ! RFC 1918 address range R8(config-ext-nacl)#deny ip 192.168.0.0 0.0.255.255 any log ! RFC 1918 address range R8(config-ext-nacl)#permit ip any any log R8(config-ext-nacl)#exit R8(config)#ip msdp sa-filter in x.1.28.2 list INBOUND_MSDP_SA_FILTER