IGMPv2 querier election issue

[Chrisw29]

Hello,

I'm new to the multicast protocol. On my switches, the igmp snooping is enabled per-port, version 2, on all of them. I have several vlans configured on the switches.

I set on one switch an IP on vlan29, and I have an IP on the management vlan. So normally, when I enter "show igmp vlan vlan29", on any switch, it should be the IP of vlan29. But it is another switch vlan management's IP that is showing as "last Querier", including the one where I added the vlan29 IP address.

I really don't understand why....I thought maybe it was because the igmp snooping is per-port, so I changed it on one test swtich to per-vlan, and even change the version to igmp version 3, but still....

Does anyone has a clue? it's been 3 weeks that I'm on this issue....

Thank you

[Samantha_R_Newm]

Hi Chris, I don't work with the EOS brand switches however generally I can tell you that for IGMP to work you need three things. They would be:
Host -  The end device that will be generating the multicast request. Most often these are in the form of a video stream.  Responsible for sending out Join and leave messages. 
Active quierier - The network component configured to periodically send out IGMP queries to build a table of MCAST groups and the source. Also responsible for listening for Join and leave messages so it can build/prune multicast streams. On older EOS devices it looks like the switch with the highest IP configured would become the active querier. With our new switches and the product line I support (SLX, VDX and MLX) you can set a switch to either be active or a passive querier. 
Source - Where the multicast stream originates from. 

The question I would pose back to you is where is your host and your source? What is that multicast group address? Does it work before you enable IGMP what happens when you enable IGMP? 
Generally when you have an active stream there is a table that you should be able to look at that would show you IGMP information. Again speaking from the product line I work with we see that as a *,G and S,G entry. 

Finally I would suggest you read the manual specific to your switch for more information to see if that helps. It should guide you in helping to properly configure IGMP for that model.

Best of luck!
Regards,
S. Newman

[Chrisw29]

Hello Samantha,

Thank you for your reply.

Actually the problem was the switch querier was using its management IP in a different vlan than the multicast group members.

I tried to disable the IGMP on its management vlan forced it by adding an IP in the multicast vlan, it did not worked, all the switches had IGMP disabled on the management VLAN.

On the exos, there is no explicit command to set a querier and it takes the lowest IP.

Regards,

Chris