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GS110EMX - 2 VLAN from the same switch: Loop issue?
Hi folks, I'm opening this discussion to be sure I'm not doing anything wrong. Long story short, my TV setupbox must be directly connected to the internet box due to my ISP's constraints đ. Un...
Letâs say it is a creative use of VLANs.
You got you untagged/tagged and PVID 100% correct. However I think you are not correct on these two counts.
1. âmy TV setupbox must be directly connected to the internet box due to my ISP's constraintsâ
2. âit appears that both VLANs are well isolated.â
The reason for this is that your final configuration is still a single subnet flat network. If your TV works in this setup, it should also work without those VLANs. Also, there is no isolation there since you have bridged the two VLANs with the hub. The only advantage I can see from that setup is that you can use two links between the top switch and the hub without creating a loop.
Here, some tests have been done.
With the setup as described in the diagram, I can ping the TV STB from my PC.
It is the expected behavior since all equipment is on the same LAN/subnet.
- Test #1:
If I unplug port 2 from my internet box, the TV STB stops working and I can no longer ping it from my PC. All other equipment is working as expected and internet access is available.
- Test #2:
If I unplug port 1 from my internet box, the TV STB continues to work and I can no longer ping it from my PC. All other equipment can be pinged from my PC, but none of them (including my PC) have access to the internet.
Based on these tests, it appears that both VLANs are well isolated.
The only connection point between my TV STB and the rest of my LAN is the integrated hub on my internet box.
Anyone to confirm that this configuration is allowed and licit? đđą
Letâs say it is a creative use of VLANs.
You got you untagged/tagged and PVID 100% correct. However I think you are not correct on these two counts.
1. âmy TV setupbox must be directly connected to the internet box due to my ISP's constraintsâ
2. âit appears that both VLANs are well isolated.â
The reason for this is that your final configuration is still a single subnet flat network. If your TV works in this setup, it should also work without those VLANs. Also, there is no isolation there since you have bridged the two VLANs with the hub. The only advantage I can see from that setup is that you can use two links between the top switch and the hub without creating a loop.
Retired_Member
Hi Kris,
First of all, thank you very much for taking the time to help me. đ
Thank you for confirming that the VLAN setup is correct. This also implies that I didn't create a loop.
Regarding your comments:
You are absolutely correct. I am breaking the rule that one VLAN equals one subnet (as I mentioned, I don't have any router).
Again, you are correct. "Isolated" is not the correct word. I should have said that they are kind of in "parallel" or "isolated" on the Netgear side. đ
Concerning my TV STB, my explanation was a shortcut.
In fact, the TV STB uses some multicast. The integrated hub on the ISP box detects that the TV STB is directly plugged in and does something special (unfortunately, I don't have more information on this point).
The correct solution should be to have no VLANs and to enable IGMP snooping on the first GS110EMX (the one plugged into the internet box) and also on the GS108E.
Many users have reported that the TV STB doesn't respect IGMP snooping very well. This is the reason why I set up those unusual VLANs, trying to do something clever.
By doing so, my ISP box believes that the TV STB is directly plugged into its port 2.
If I have some time this weekend, I will try to remove the VLANs and enable IGMP snooping.
Best regards,
Seb
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