Multicast Static Routes - H3C S3610-28P Operation Manual

Operation Manual – Multicast Protocol
H3C S3610&S5510 Series Ethernet Switches
Figure 8-1 RPF check process
A multicast packet from Source arrives on Vlan-int1 of Switch C, and the
corresponding forwarding entry does not exist in the multicast forwarding table of
Switch C. The Switch C performs an RPF check, and finds in its unicast routing
table that the outgoing interface to 192.168.0.0/24 is Vlan-int2. This means that
the interface on which the packet actually arrived is not the RPF interface. The
RPF check fails and the packet is discarded.
A multicast packet from Source arrives on Vlan-int2 of Switch C, and the
corresponding forwarding entry does not exist in the multicast forwarding table of
Switch C. The switch performs an RPF check, and finds in its unicast routing table
that the outgoing interface to 192.168.0.0/24 is the interface on which the packet
actually arrived. The RPF check succeeds and the packet is forwarded.

8.1.3 Multicast Static Routes

If the topology structure of a multicast network is the same as that of a unicast network,
receivers can receive multicast data via unicast routes. However, the topology structure
of a multicast network may differ from that of a unicast network, and some routers may
support only unicast but not multicast. In this case, you can configure multicast static
routes to provide multicast transmission paths that are different from those for unicast
traffic. Note the following two points:
A multicast static route only affects RPF checks, and not guides multicast
forwarding, so it is also called an RPF static route.
A multicast static route is effective on the multicast router on which it is configured,
and will not be broadcast throughout the network or injected to other routers.
A multicast static route is an important basis for RPF checks. With a multicast static
route configured on a router, the router searches the unicast routing table and the
multicast static routing table simultaneously in a RPF check, chooses the optimal
Chapter 8 Multicast Routing and Forwarding
8-4
Configuration