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GS110EMX - 2 VLAN from the same switch: Loop issue?

LapinFou14
Aspirant

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 😒.

Unfortunately my house is quite old and did not have any RJ45 wiring when I bought it.

I've been able to add some 1G/10G wires at strategic points throughout my house.

 

I have only one RJ45 wire from the ISP box to my TV, but I have some equipment that needs an internet connection behind my TV, such as a home cinema and a multimedia player. 😓

 

My goal is to make it appear as though the TV STB is directly connected to the ISP box. To accomplish this, I bought a GS108E and installed it behind my TV. For your information, I also have a GS110EMX upstairs.

 

To achieve this, I enabled the advanced 802.1Q VLAN menu in my GS110EMX and GS108E.

VLAN 1 is for the normal internet connection (and, of course, home LAN), while VLAN 2 is used to make a direct connection between my TV STB and my ISP box.

 

Please see the attached diagram (tmp.png) for a visual representation.

 

Initially, it did not work (no internet connection) because the GS110EMX detected a loop, which is true if no VLANs were used. After disabling Loop Detection, everything worked as expected.

However, as I'm not a network expert, I want to make sure that I did not do anything wrong by disabling the Loop Detection. 😁

If a Netgear expert could provide some advice, it would be wonderful. 🤞

 

Last point:

I know that a router between my ISP box and the 1st GS110EMX could be a cleaner solution, but I don't want to buy one just for this TV STB. Additionally, this year, my slow 12MB ADSL connection should be upgraded to a 2GB optical fiber. 😍 Meaning, I should buy a 10G router. 😨

LapinFou14_0-1679160168742.png

 

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Retired_Member
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Re: GS110EMX - 2 VLAN from the same switch: Loop issue?

@LapinFou14 

 

Let’s 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. “my TV setupbox must be directly connected to the internet box due to my ISP's constraints”

2. “it appears that both VLANs are well isolated.”

 

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.

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LapinFou14
Aspirant

Re: GS110EMX - 2 VLAN from the same switch: Loop issue?

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.

 

Message 2 of 5
LapinFou14
Aspirant

Re: GS110EMX - 2 VLAN from the same switch: Loop issue?

Anyone to confirm that this configuration is allowed and licit? 🙏😢

Message 3 of 5
Retired_Member
Not applicable

Re: GS110EMX - 2 VLAN from the same switch: Loop issue?

@LapinFou14 

 

Let’s 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. “my TV setupbox must be directly connected to the internet box due to my ISP's constraints”

2. “it appears that both VLANs are well isolated.”

 

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.

Message 4 of 5
LapinFou14
Aspirant

Re: GS110EMX - 2 VLAN from the same switch: Loop issue?

@Retired_Member 

Hi Kris,

 

First of all, thank you very much for taking the time to help me. 👍

Thank you for confirming that the VLAN setup is correct. This also implies that I didn't create a loop.

 

Regarding your comments:

  1. You are absolutely correct. I am breaking the rule that one VLAN equals one subnet (as I mentioned, I don't have any router).

  2. 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. 😅

  3. 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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