HP VPN Firewall Appliances Appendix Protocol Reference

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Figure 45 Changing an RPF route
As shown in Figure 45, when no static multicast route is configured, Router C's RPF neighbor on the path
back to Source is Router A. The multicast information from Source travels along the path from Router A to
Router C, which is the unicast route between the two routers. When a static multicast route is configured
on Router C and Router B is configured as Router C's RPF neighbor on the path back to Source, the
multicast information from Source travels from Router A to Router B and then to Router C.
Creating an RPF route
When a unicast route is blocked, multicast traffic forwarding might be stopped due to lack of an RPF
route. You can create an RPF route by configuring a static multicast route for a given multicast source, so
that a multicast routing entry is created to guide multicast traffic forwarding.
Figure 46 Creating an RPF route
As shown in Figure 46, 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
GE0/1
1.1.1.2/24
GE0/1
1.1.1.1/24
GE0/2
2.2.2.2/24
GE0/1
2.2.2.1/24
Source
192.168.0.1/24
Source/Mask
Multicast Routing Table Static on Router C
192.168.0.0/24
Interface
GE0/1
RPF neighbor/Mask
1.1.1.1/24
Source/Mask
Multicast Routing Table Static on Router D
192.168.0.0/24
Interface
GE0/1
RPF neighbor/Mask
2.2.2.2/24
OSPF domain
RIP domain
Router A Router B Router C
Router D
Receiver
Receiver
Multicast packets Multicast static route