75
Figure 27 Changing an RPF route
As shown in
, when no static multicast route is configured, Switch C's RPF neighbor on the
path back to the source is Switch A. The multicast information from the source travels along the path
from Switch A to Switch C, which is the unicast route between the two switches. You can configure a
static multicast route on Switch C, and specify Switch B as Switch C's RPF neighbor on the path
back to the source. Then, multicast information from the source travels from Switch A to Switch B,
and then to Switch C.
Creating an RPF route
When a unicast route is blocked, multicast traffic forwarding might be stopped due to lack of an RPF
route. By configuring a static multicast 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
, the RIP domain and the OSPF domain are unicast isolated from each other.
When no static multicast route is configured, the receivers in the OSPF domain cannot receive the
multicast packets that the multicast source sent in the RIP domain. You can configure a static
Vlan-int10
1.1.1.2/24
Vlan-int10
1.1.1.1/24
Vlan-int20
2.2.2.2/24
Vlan-int20
2.2.2.1/24
Source
192.168.0.1/24
Source/Mask
Multicast Routing Table Static on Switch C
192.168.0.0/24
Interface
Vlan-int10
RPF neighbor/Mask
1.1.1.1/24
Source/Mask
Multicast Routing Table Static on Switch D
192.168.0.0/24
Interface
Vlan-int20
RPF neighbor/Mask
2.2.2.2/24
OSPF domain
RIP domain
Switch A
Switch B
Switch C
Switch D
Receiver
Receiver
Multicast packets
Multicast static route
