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Title: IGMP querier and foreign switches
Post by: Jelmer de Jong on May 28, 2022, 11:20:10 AM
I've set up SG300 and SG350 switches per the Audinate/Yamaha configuration. Everything works fine unless there is another switch introduced to the system. It could be another SG series, or a different brand, that doesn't matter. The problem lies withing IGMP snooping and the active querier.
Quote
You can set multiple switches to be querier. However, only one querier per VLAN, should be active at any one time. If you are configuring multiple queriers in the same VLAN, then the other querier(s) should act as a failover system. The way it works is by the querier IP addresses.  The querier with the lowest IP address value, will be the elected querier for that VLAN

Let's say it is a Yamaha desk with a stage rack for inputs, stage rack for outputs and to make things wild there is another desk which does monitors. Thanks to the wonderful world of Dante both desks can share racks. There are also some wireless mics who can talk Dante.

- Switch at FOH 192.168.200.11
- Switch at monitor 192.168.200.12
- Switch at input rack 192.168.200.51
- Switch at output rack 192.168.200.52
- Switch at wireless rack 192.168.200.201

To keep it simple there is no redundant network yet, just the primary Dante ports connected to switches and switches are connected to each other. Everything works fine and the FOH switch becomes the active IGMP querier as it has the lowest IP of them all. When you disconnect the FOH switch and wait a few second the switch at the monitor desk becomes the new active IGMP querier.
This is all fun and games until somebody brings their own switch with a IGMP querier enabled in a totally different IP subnet. Then there are two queriers active on the network and things go south. It could be a FOH wizzard with their own rack of toys, a broadcast truck stealing all our channels or even something simple like a extra rack of wireless rented from a competitor. When one of the switches has also been configured by the Yamaha guide but has a IP address of 10.10.10.10 then they don't talk to each other and you end up with multiple IGMP queriers and Dante channels randomly appearing or disappearing from the network.

Is there a 'one size fits all' solution to mitigate this? Other than going back no analogue....  ;D
Title: Re: IGMP querier and foreign switches
Post by: Erik Jerde on May 28, 2022, 01:05:46 PM
I've set up SG300 and SG350 switches per the Audinate/Yamaha configuration. Everything works fine unless there is another switch introduced to the system. It could be another SG series, or a different brand, that doesn't matter. The problem lies withing IGMP snooping and the active querier.
Let's say it is a Yamaha desk with a stage rack for inputs, stage rack for outputs and to make things wild there is another desk which does monitors. Thanks to the wonderful world of Dante both desks can share racks. There are also some wireless mics who can talk Dante.

- Switch at FOH 192.168.200.11
- Switch at monitor 192.168.200.12
- Switch at input rack 192.168.200.51
- Switch at output rack 192.168.200.52
- Switch at wireless rack 192.168.200.201

To keep it simple there is no redundant network yet, just the primary Dante ports connected to switches and switches are connected to each other. Everything works fine and the FOH switch becomes the active IGMP querier as it has the lowest IP of them all. When you disconnect the FOH switch and wait a few second the switch at the monitor desk becomes the new active IGMP querier.
This is all fun and games until somebody brings their own switch with a IGMP querier enabled in a totally different IP subnet. Then there are two queriers active on the network and things go south. It could be a FOH wizzard with their own rack of toys, a broadcast truck stealing all our channels or even something simple like a extra rack of wireless rented from a competitor. When one of the switches has also been configured by the Yamaha guide but has a IP address of 10.10.10.10 then they don't talk to each other and you end up with multiple IGMP queriers and Dante channels randomly appearing or disappearing from the network.

Is there a 'one size fits all' solution to mitigate this? Other than going back no analogue....  ;D

I havenít specifically tangled with this problem and when reading through my gut was that you just donít allow other switches on the network.  However, reading all the way through you present a reasonable situation where that may not be possible.  Without getting into my switches and the Cisco docs to see if itís possible my gut is to find a way to block IGMP across the links to ď3rd partyĒ switches.  Of course that may have negative knock-on effects too.

For the small rack issues it might be prudent to just have a few loaner switches that you could provide and just have everything get patched into those.  For larger setups itís probably appropriate to integrate it into your advance process a method to coordinate these things.  After all we already coordinate a lot of other things itís only reasonable to expect that as IT networking becomes show critical that that would need to be coordinated as well.  The problem is when the people youíre interfacing with have no idea whatís going on and either are using a default config or had an IT person set it up whoís not available. 
Title: Re: IGMP querier and foreign switches
Post by: Russell Ault on May 29, 2022, 12:52:04 AM
{...} my gut is to find a way to block IGMP across the links to ď3rd partyĒ switches.  Of course that may have negative knock-on effects too. {...}

If my understanding is correct, the only way to really achieve this would be to place a router between the "house" network and the "3rd party" network, which IIRC in turn would require Dante Domain Manager in order to be able to send the audio through the router (the negative knock-on effects of which are primarily cost and complexity).

{...} For the small rack issues it might be prudent to just have a few loaner switches that you could provide and just have everything get patched into those.  For larger setups itís probably appropriate to integrate it into your advance process a method to coordinate these things.  After all we already coordinate a lot of other things itís only reasonable to expect that as IT networking becomes show critical that that would need to be coordinated as well.  The problem is when the people youíre interfacing with have no idea whatís going on and either are using a default config or had an IT person set it up whoís not available. 

This all makes sense to me. Mercifully, most (all?) of the switches I've run into don't have IGMP snooping enabled be default, so any "foreign" switch that someone has gone to the trouble of enabling IGMP snooping on will hopefully also be accompanied by a person who can make the necessary configuration changes (or, at the very least, their phone number).

-Russ