Layer2 Multicast Troubleshooting tips. Some stuff I learned today from the SR guys at work.
Show ip igmp snooping (Confirms which host are sending IGMP reports as you can trace back what’s connected to that specific port)
Show ip igmp snooping groups (Confirms which groups hosts are trying to subscribe to)
Show spanning-tree vlan X/X (Confirms which way the multicast data is flowing)
So how do confirm multicast data is actually being disseminated from a host on a layer 2 switch? You get the big guns out and put a sniffer up. That’s the fastest and easiest way to determine why host's that are sending out reports are not getting multicast data. You can also run into issues where a specific ASIC for a group of ports is not working properly (Not common but it does happen).
Eventually I would like to do reviews on all the tools at have at my possesion at work, to name a few Gigamon, Netscout, Apcon Matrix Switch, Network General Sniffer and Niksun. Arista switches and a Ton of nexus gear.
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