This demo will also be short, focusing on how to create an IGMP
report on a receiver that will get converted to a PIM join for
testing multicast in your lab. Note that the configuration for MLD in
IPv6 will be very slightly different.
The procedure will be the same.
We need to configure the interface on which we want to
receive multicast with an IGMP report. First, let's turn on
debug so we can see it happen.
Okay,
now to the interface. We'll go into configure mode, we'll go
under the interface configuration, and we'll add the config,
ip igmp join‑group 239.3.2.1,
which is the multicast group we want to join. Based on the debug, we can see
the IGMP report was generated and sent out of the interface.
Let's go over to the Last Hop Router and confirm that it was received. On
the Last Hop Router, we're going to do a show ip igmp membership in order
to see what IGMP reports have been received.
The LHR shows an IGMP report for that group on the downstream interface.
Now let's see if we have a PIM join in the mroute
table, and here's the PIM join.
We can see the outgoing interface is the one on which it received the IGMP
report and that it has resolved the upstream address to the RP.
If we follow this on,
we'd see that each router has that *,G any‑source join
in its mroute table up to the RP.
Since we aren't currently sending traffic to this group,
there will be no source registered. In the next demo, we will send traffic, and we'll see some interesting traffic on a shared segment.