This is going to be a very short and sweet demo.
I'm simply going to demonstrate an effective way to generate multicast
traffic in a lab environment so that those playing along at home can set
up their own multicast labs and see it work.
I'm going to show a non‑working flow and then a working flow just so
you'll know if the multicast is working in your lab or not.
We'll go ahead and ping this multicast group and do it five
times to give time for the multicast setup.
This flow is broken.
ICMP is a little goofy with multicast.
It can actually be used to test flows because the receivers will
send back an ICMP echo reply to the source.
In this case, we get no echo reply, so we know it's not working.
There could be a lot of reasons for that, and this
isn't a troubleshooting video.
But one reason I'll include here is because it's appropriate. Make sure
the First Hop Router has PIM enabled towards the source.
The reason for that is while the source itself doesn't need PIM or
might not even be aware of PIM, the upstream First Hop Router does need
PIM to listen for the source's traffic flow.
Okay, let's see a fixed flow so you can see what a fixed flow looks like.
We'll go ahead and set the ping again. And as you can see,
in this case, we know that a receiver got the flow because it sent back echo replies.