Multicast Static Routes - HP A6600 Configuration Manual

the RPF interface, the router forwards the packet to all the outgoing interfaces. Otherwise it discards
the packet.
Assume that unicast routes are available in the network, MBGP is not configured, and no multicast static
routes have been configured on Router C, as shown in
from the multicast source to the receivers. The multicast forwarding table on Router C contains the (S, G)
entry, with POS 5/0/0/1 as the incoming interface.
Figure 18 RPF check process
When a multicast packet arrives on interface POS 5/0/0/1 of Router C, because the interface is
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the incoming interface of the (S, G) entry, the router forwards the packet to all outgoing interfaces.
When a multicast packet arrives on interface POS 5/0/0 of Router C, because the interface is not
•
the incoming interface of the (S, G) entry, the router performs an RPF check on the packet. The router
searches its unicast routing table and finds that the outgoing interface to Source (the RPF interface) is
POS 5/0/0/1. This means the (S, G) entry is correct and packet arrived along a wrong path. The
RPF check fails and the packet is discarded.

Multicast static routes

A multicast static route is an important basis for RPF check. Depending on the application environment, a
multicast static route can change an RPF route and create an RPF route.
Changing an RPF route
Typically, the topology structure of a multicast network is the same as that of a unicast network, and
multicast traffic follows the same transmission path as unicast traffic does. By configuring a multicast static
route for a given multicast source, you can change the RPF route to create a transmission path for
multicast traffic that is different from that for unicast traffic.
Figure 18. Multicast packets travel along the SPT
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