/mcpip22-72a# show ip mroute 224.1.1.1 count IP Multicast Statistics 3 routes using 2032 bytes of memory 2 groups, 0.50 average sources per group Forwarding Counts: Pkt Count/Pkts per second/Avg Pkt Size/Kilobits per second Other counts: Total/RPF failed/Other drops(OIF-null, rate-limit etc)
Group: 224.1.1.1, Source count: 1, Packets forwarded: 0, Packets received: 471 Source: 10.1.1.1/32, Forwarding: 0/0/0/0, Other: 471/471/0 ip22-72a#
You can see from the Other counts that traffic gets dropped due to RPF failure: total 471 drops, due to RPF failure – 471… Enter the show ip rpf <source> command in order to see if there is an RPF error:
<#root> ip22-72a# show ip rpf 10.1.1.1 RPF information for ? (10.1.1.1) RPF interface: Ethernet2/0 RPF neighbor: ? (0.0.0.0) RPF route/mask: 10.1.1.1/32 RPF type: unicast (static) RPF recursion count: 0 Doing distance-preferred lookups across tables ip22-72a#
Cisco IOS® calculates the RPF interface in this way. Possible sources of RPF information are Unicast Routing Table, MBGP routing table, DVMRP routing table, and Static Mroute table. When you calculate the RPF interface, primarily administrative distance is used in order to determine exactly which source of information the RPF calculation is based on. The specific rules are: All previous sources of RPF data are searched for a match on the source IP address. When you use Shared Trees, the RP address is used instead of the source address. • If more than one match route is found, the route with the lowest administrative distance is used. • If the administrative distances are equal, then this order of preference is used: Static mroutes 1. DVMRP routes 2. MBGP routes 3. •