Static Multicast Routes - HP MSR2003 Configuration Manual

Figure 15 RPF check process
IP Routing Table on Router C
Destination/Mask
192.168.0.0/24
Source
192.168.0.1/24
As shown in
and no static multicast routes have been configured on Router C. Multicast packets travel along the SPT
from the multicast source to the receivers. The multicast forwarding table on Router C contains the (S, G)
entry, with GigabitEthernet 1/0/2 as the incoming interface.
• If a multicast packet arrives at Router C on GigabitEthernet 1/0/2, Router C forwards the packet
out of all outgoing interfaces.
If a multicast packet arrives at Router C on GigabitEthernet 1/0/1, Router C performs an RPF check
•
on the packet. Router C searches its unicast routing table and finds that the outgoing interface to the
source (the RPF interface) is GigabitEthernet 1/0/2. In this case, the (S, G) entry is correct, but the
packet traveled along a wrong path. The packet fails the RPF check, and Router C discards the
packet.

Static multicast routes

Depending on the application environment, a static multicast route can change an RPF route or 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. You can configure a static
multicast route for a multicast source to change the RPF route. As a result, the router creates a transmission
path for multicast traffic that is different from the transmission path for unicast traffic.
Interface
GE1/0/2
Router A
Multicast packets
Figure 15, assume that unicast routes are available in the network, MBGP is not configured,
Router B
GE1/0/1
GE1/0/1
GE1/0/2
Router C
42
Receiver
Receiver