Refusing Multicast Traffic - Dell Force10 C150 Configuration Manual

Figure 33-1. Multicast Flooding in a PIM-DM Network
Source
Group Address: 239.192.0.1
R1

Refusing Multicast Traffic

If a PIM-DM router has no receivers for a group, it refuses multicast traffic by sending a PIM Prune
message to address 224.0.0.13 out of the source interface. The upstream neighbor receives the prune
message and determines if it has any remaining neighbors downstream. If it does not, it propagates the
prune message upstream out of the source interface. Likewise, all remaining routers between the receiver
and the source independently determine whether to propagate the prune message until no router receives
unwanted traffic for the (S,G).
Any router that receives multicast traffic on a port that does not lead back to the source (via the PIM-DM
selected path) also generates a prune message.
In Figure
for the reverse path forwarding (RFP) check and generates a prune message so that routers upstream stop
sending traffic for the group. R2 then has no PIM-DM neighbors downstream and so sends a prune
message to R1.
Figure 33-2. Refusing Multicast Traffic in a PIM-DM Network
Source
Group Address: 239.192.0.1
R1
748 | PIM Dense-Mode
Hello
Adjacency
R3
33-1, R3 receives multicast traffic by two paths. In
Prune
R3
R2
Receiver
R4
Figure
R2
Receiver
R4
PIM-DM 001
33-2, PIM-DM selects only one path
PIM-DM 002