Multicast stops working after about 20 minutes

Hi again,

Yes, you simply turn off DVMRP and enable PIM-DM instead. I think PIM-DM is a much better solution for a network your size (based on the topology you gave). It is simpler and it "just works". It has some downsides, but you won't notice those unless you get more routing hops. At that point you would start looking into PIM-SM. But for now, PIM-DM is good.

To enable PIM-DM, you need to:
1. Enable mcst routing, globally.
System > Routing > Multicast > Global Configuration > Enable Admin mode here and click Apply.

2. Enable IGMP routing globally.
System > Routing > Multicast > IGMP > Global Configuration > Enable Admin mode here and click Apply.

3. Enable IGMP routing on each VLAN.
System > Routing > Multicast > IGMP > Routing Interface Configuration > Enable Admin mode on your VLANs here, and click Apply.

4. Enable PIM-DM globally.
System > Routing > Multicast > PIM > Global Configuration > Enable PIM-DM mode here and click Apply.

5. Enable PIM routing on each VLAN.
System > Routing > Multicast > PIM > Interface Configuration > Enable Admin mode on your VLANs here, and click Apply.

As for the IGMP snooping. I would encourage you to do snooping per VLAN. Reason being that it gives you more control. Say, I want to do snooping for two VLANs, but not a 3rd VLAN. So, my suggestion is the guide was do to snooping and querier, per VLAN. You can do it as follows:

1. Enable IGMP snooping globally.
Switching > Multicast > IGMP Snooping > Configuration > Enable Admin mode here and click Apply.

2. Enable IGMP snooping on your VLANs.
Switching > Multicast > IGMP Snooping > IGMP VLAN Configuration > Enable Admin mode for you VLANs here and click Apply.

3. Allow querier mode each VLAN.
Switching > Multicast > IGMP Snooping > IGMP VLAN Configuration > Enable Proxy Querier mode for you VLANs here and click Apply.

4. Enable IGMP querier globally.
Switching > Multicast > IGMP Snooping > Querier Configuration > Enable Querier Admin mode here and click Apply. Leave the IP at 0.0.0.0 in this section.

5. Enable IGMP querier on your VLANs.
Switching > Multicast > IGMP Snooping > Querier VLAN Configuration > Type in VLAN ID, for the VLAN you want to enable querier mode for. Also, enable "Querier Election Participate Mode" and specity the querier IP address. Hereafter, click Add.

As for the querier IP address. You are correct that the IP you specify here, is just an arbitrary IP. It is solely used for an election model. The VLAN Querier with the lowest IP value, will be the querier for that VLAN. I would using something like this:
- Core switch VLAN 10 querier IP: 1.1.1.10
- Core switch VLAN 20 querier IP: 1.1.1.20
- Destibution switch VLAN 10 querier IP: 2.2.2.10
- Distribution switch VLAN 20 querier IP: 2.2.2.20
- etc.
This way I create an election system where my core is main querier and my distribution switch will take over, in case the core experiences issues within one or several VLANs. I hope that makes sense?

The reason you see 172.16.210.17 is likely just because the switch chooses the same IP as it's own management IP interface (per default). But, you want to select the IP value yourself, based on a hierarchy system that you create - i.e. my core is the main querier, then my distribution, etc.

Any questions - let me know.

Cheers