H3C Technologies H3C S10500 Series Switches - Manual (Page 94)

79
Figure 27 Changing an RPF route
As shown in Figure 27 , when no multicast static route is configured, Switch C’s RPF neighbor on the path
back to Source is Switch A. The multicast information from Source travels along the path from Switch A
to Switch C, which is the unicast route between the two routers. When a multicast static route is
configured on Switch C and Switch B is configured as Switch C’s RPF neighbor on the path back to
Source, the multicast information from Source travels from Switch A to Switch B and then to Switch C.
RPF route creation
When a unicast route is blocked, multicast traffic forwarding might be stopped due to lack of an RPF
route. By configuring a multicast static route for a given multicast source, you can create an RPF route so
that a multicast routing entry is created to guide multicast traffic forwarding regardless of whether a
unicast route is available.
Figure 28 Creating an RPF route
As shown in Figure 28 , the RIP domain and the OSPF domain are unicast isolated from each other. When
no multicast static route is configured, the hosts (Receivers) in the OSPF domain cannot receive the
multicast packets that the multicast source (Source) sent in the RIP domain. After you configure a multicast