Objectives
The simulator ticks each one as soon as the network meets it.
In the system view of R1, R2 and R3 run multicast routing-enable.
Enable pim dm on every addressed GigabitEthernet interface.
On R3 enable igmp on GigabitEthernet0/0/1 (PC3’s LAN), and join 239.1.1.1 on PC3.
From SRC ping 239.1.1.1: PC3 replies.
On R3, display pim routing-table shows the (10.1.1.10, 239.1.1.1) entry with Protocol: pim-dm.
Before you start
PIM must be enabled on every link the stream crosses, and IGMP on the receiver LAN. On VRP a command such as pim dm is refused until multicast routing-enable is set in the system view.
Concept
PIM dense mode: flood and prune
Dense mode assumes every network wants the stream. The first packets flood out of every PIM interface that passes the RPF check, and routers with no receivers downstream send a Prune back, so the flood shrinks to the branches that need it. The flood repeats every three minutes.
Concept
IGMP: how a receiver asks for a group
A multicast group (224.0.0.0/4) is an address many receivers can listen to at once. A host tells its local router it wants a group with an IGMP membership report; the router then pulls the stream toward that LAN. IGMPv2 can only name the group; IGMPv3 can also name the source.
