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Figure 23 Changing an RPF route
As shown in Figure 23, when no static multicast route is configured, Switch C's RPF neighbor on the path
back to the source is Switch A. The multicast data from the source travels through Switch A to Switch C.
You can configure a static multicast route on Switch C and specify Switch B as its RPF neighbor on the
path back to the source. The multicast data from the source will travel along the path: Switch A to Switch
B and then to Switch C.
Creating an RPF route
When a unicast route is blocked, multicast forwarding might be stopped due to lack of an RPF route. In
this case, you can create an RPF route by configuring a static multicast route for a given multicast source.
A new multicast routing entry will be created to guide multicast forwarding.
Figure 24 Creating an RPF route
As shown in Figure 24, the RIP domain and the OSPF domain are unicast isolated from each other. When
no static multicast route is configured, the receiver hosts in the OSPF domain cannot receive the multicast
packets from the multicast source in the RIP domain. You can configure static multicast routes on Switch
Vlan-int10
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Vlan-int10
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Vlan-int20
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Source/Mask
Multicast Routing Table Static on Switch C
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Interface
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Multicast Routing Table Static on Switch D
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Interface
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OSPF domain
RIP domain
Switch A Switch B Switch C
Switch D
Receiver
Receiver
Multicast packets Multicast static route
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