VLAN and dumb switches downstream of smart switches

[saltwater]

I will be purchasing Ubiquity router and switch so I haven't had a chance to get my hands dirty with VLAN setup. My question is if on the main switch a port is tagged or setup to be VLAN200 and that port is then connected into say, a 5 port dumb switch, are all the ports of the dumb switch contained within the VLAN200?

 

[mikeynags]

yes

 

[reflection]

Yes. What are you trying to do?

If you set the port on the managed switch to be a trunk, your dumb switches will forward the tagged frames (there are use cases for that if your end devices on your dumb switch understand tagged frames).

 

[saltwater]

Yes. What are you trying to do?

If you set the port on the managed switch to be a trunk, your dumb switches will forward the tagged frames (there are use cases for that if your end devices on your dumb switch understand tagged frames).

It's more a theoretical question, trying to come to grips with VLAN. In essence, the dumb switch merely inherits whatever the assigned VLAN is, if any.

For argument sake, at the dumb switch, it's ok that 4 of the ports are assigned to VLAN200 but the 5th port is a Wireless Access Point. That AP is on the VLAN200, when it is preferred to be separated away, not be included in VLAN200.

 

[reflection]

It's more a theoretical question, trying to come to grips with VLAN. In essence, the dumb switch merely inherits whatever the assigned VLAN is, if any.

For argument sake, at the dumb switch, it's ok that 4 of the ports are assigned to VLAN200 but the 5th port is a Wireless Access Point. That AP is on the VLAN200, when it is preferred to be separated away, not be included in VLAN200.

I assume this is an autonomous AP.

1. If the managed switchport towards the dumb switch is set to access vlan 200, then all ports on the dumb switch will be vlan 200. Which means your AP will be on VLAN200 and all your wifi clients would be on vlan 200 (you knew this).
2. If the managed switchport towards the dumb switch is set to trunk, then all ports on the dumb switch will be trunks. Which means your AP will be on a trunk. This would allow you to break up your wifi clients to different vlans. For example, one SSID could be mapped to vlan 200, another to vlan 300, another to vlan 400. This is good for a guess wifi or kids wifi.

If you want to do option 2, then on your managed switch, you should set your trunk with a native vlan 200. This allows you to still trunk to the AP, but anything in vlan 200 will be untagged. This means your endpoints (e.g. cameras) won't need to to support tagging. They would think they are on vlan 200.

If you have a controller based AP, then you could tunnel everything back to the controller and drop off vlans at the controller.

Personally, I have three SSIDs at home (guest, IoT, internal) on the same AP.

 

[JonW]

Unmanaged (dumb) switches can give some inconsistent results when trying to handle tagged data. Some switches will strip the tags off. Some will see it as corrupt data as the frame size is larger than a standard untagged frame. Some will simply pass on the tagged data as someone mentioned above.

To minimize the chances of something odd happening, your best bet is to configure the managed switch so that it sends untagged data to the dumb switch. You can set this on the port that is being used to send data to the dumb switch. The port should be part of VLAN 200 and will remove the tag from anything outgoing to the dumb switch and will tag any data coming from the dumb switch back into the managed switch.

 

[saltwater]

Thanks for the advice everyone. VLAN, it surely is a major topic within a LAN network. The above is purely theoretical as I've subsequently purchased (awaiting delivery) a 48 port Ubiquiti POE switch and at this point in time I can't see a requirement to be connecting further switches dumb or managed.

As an aside: LAN Network = Local Area Network Network, must be the same as an ATM machine or PIN number.