igmp snooping in routeros

RouterOS Beginner Basics
1

Hi,

I’ve setup a small lab to experiment igmp snooping of bridge in routeros.
Here is my simple setup:
setup.PNG
All devices are CHR v6.48.1, where on ‘Switch’ I have setup bridge that bridges R1, R2 and R3 together. IGMP snooping on the bridge is enabled.
On both R1 and R2, I enabled OSPF (such that it starts generating multicast traffic) while on R3 OSPF is disabled.
I did wireshark capture on the link between ‘Switch’ and ‘R3’, it seems that OSPF hello packet is forward to R3 as well, am I correct to assume that multicast traffic in this case is flooded across the network? Will igmp snooping prevent multicast traffic being flooded to whole network?

Thanks!
switch.rsc (1.2 KB)
r3.rsc (826 Bytes)
r2.rsc (1000 Bytes)
r1.rsc (1000 Bytes)

2

Yes, essentially IGMP snooping exists to determine which ports on a LAN segment need to participate in multicast streams and prevents the flooding of traffic to ports that don’t need it.