Understanding VLAN trunking and its usage in wireless networks

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Understanding VLAN trunking and its usage in wireless networks

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Understanding VLAN trunking and its usage in wireless networks
Understanding VLAN trunking and its usage in wireless networks
2021-04-05 21:16:06

Hi everybody,

 

I'm still fairly new to using VLANs. Up until now I'm only used it to "cut a switch into slices" of independent VLANs with no interconnection and even with separate uplink cables.

 

Let me split my posts into 2 parts.

 

1.

What I would like to do first is trunking, so transport multiple VLANs over 1 cable and take the VLANs apart on another switch again.

 

I understand these steps are required for this:

  • I go to 802.1Q VLAN and create the VLANs I need
  • additionally I go to port config and set the default VLAN for each port.
  • Furthermore I set the uplink ports to trunk (on both switches connected by a shared cable)

 

So when connecting to a port dedicated to a certain VLAN I should also be able to reach out to ports of that VLAN on ANOTHER switch (but only to those and not the other VLAN-ports).

 

Did I get that right?

 

2.

I'd like to use this to be able to utilize this with a WIFI access point to broadcast 2 seperate WIFIs with 1 VLAN each. But the WIFI AP is connected via 1 cable only.

 

I would assume I need to configure the port the access point is connected as "trunk" and configure it to belong to the 2 desired VLANs, wouldn't I?

 

Unfortunately when doing this last step the WIFI AP becomes unavailable.

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#1
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Re:Understanding VLAN trunking and its usage in wireless networks
2021-04-05 21:56:40

@ESCaNDIO 

 

Hey

 

Hopefully this helps a bit :)

 

1.

What I would like to do first is trunking, so transport multiple VLANs over 1 cable and take the VLANs apart on another switch again.

 

I understand these steps are required for this:

  • I go to 802.1Q VLAN and create the VLANs I need 
  • additionally I go to port config and set the default VLAN for each port.
  • Furthermore I set the uplink ports to trunk (on both switches connected by a shared cable)

 

So when connecting to a port dedicated to a certain VLAN I should also be able to reach out to ports of that VLAN on ANOTHER switch (but only to those and not the other VLAN-ports).

 

Did I get that right?

 

YES exactly as you say -   Take 2 switches with 3x vlans, lets say   Home, Office, LivingRoom.   These are applied to ports 1, 2 and 3 respectively on both switches, we then connect PORTS 8 on both switches to each other and set for TRUNK.   

 

Any data coming from LivingRoom VLAN (port 3) on switch 1, will be sent down the trunk (port 8) to switch 2.  Switch 2 will read the VLAN tag and then send it down Port 3 to the LivingRoom VLAN device on the other end. 

 

 

 

2.

I'd like to use this to be able to utilize this with a WIFI access point to broadcast 2 seperate WIFIs with 1 VLAN each. But the WIFI AP is connected via 1 cable only.

 

I would assume I need to configure the port the access point is connected as "trunk" and configure it to belong to the 2 desired VLANs, wouldn't I?

 

Unfortunately when doing this last step the WIFI AP becomes unavailable.

 

Im guessing you are using a controller?   If so the VLANs IDs are set in the SSID setup under advanced > VLAN  as shown below

 

 

This means anyone on that SSID is now on the VLAN 10, do the same for the other SSIDS (20, 30 etc)

 

Now you need to create a Profile and add the VLANs you want to allow access, noting the native network will be your backbone / management network (likely just LAN) ..  apply this to the LAN port on the switch where you have the AP connected.

 

 

SDN is a bit different from Cisco or Manual VLANs, its all about profiles and native networks.  This video here may help you more than my ramblings :)

 

https://www.youtube.com/watch?v=xsXgDIMyj6M&t=440s

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#2
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Re:Understanding VLAN trunking and its usage in wireless networks
2021-04-06 20:59:55

@Philbert Thanks a lot for your response!

 

Sorry for the late response, busy day.

 

About question 1:

Ok, then my understanding was at least correct. Unfortunately I can't get it working in my actual setup.

It may have to do with both models being of very different age. I was surprised myself to see an entirely new interface on the recently procured one than on all the old ones I've been using for a while already.

 

I have found videos demonstrating/confirming the setup I've done on the old one, but I can't fully apply that on the new user interface. I cannot find the "trunk" setting anymore. Is "Acceptable Frame Types" the new "Access/Trunk/General"?

 

Could you check the following screenshots and see if you can discover a config mistake?

 

In my case the VLAN I'd like to see VLAN ID 4 spanned over both switches.

 

Physical connection:

Old switch: trunk port 1      -------    18 trunk port of new switch

 

Members of VLAN 4:

                         1,15,21-24 -------    1/0/8,1/0/18,1/0/39-46

 

On the right in group 39-46 there's a DHCP server connected which is happily distributing addresses across the ports 39-46. But when connecting to e.g. to port 15 on the left I won't get an address.

 

Old switch:

 

 

 

 

New switch

 

 

 

 

 

About question 2:

 

The cable switches are all from TP-Link. The wireless access point is from Ubiquitous Networks, a Wireless AC Pro. I'm not certain what you mean by controller, probably the software running on another computer to manage the wireless access point(s).


I have a regular wifi with no actively assigned VLAN ID (like on the cable switches) which is the regular LAN. The specific network has the ID 4 (not the one from above, serves another purpose).

 

I guess the setting of the access point is not the (only) problem. As I wrote in the first post the wifi ap and all its clients become unavailable when configuring its physical port on the cable switch as trunk or adding it to the special vlan group.

 

I'd prefer to focus on solving problem NR. 1 and then dive further into the wifi one. Could also be a thing for the other vendor's forum.

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#3
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Re:Understanding VLAN trunking and its usage in wireless networks
2021-04-12 20:13:18

Hi everybody,

 

I was able to solve it myself. To simplify things let's use 2 equal switches. The settings will be equal on both sides.

 

Topic 1, getting two switches connected

 

This is what we want:

 

1 Port that physically connects both switch

2 default VLAN

3 default VLAN

4 default VLAN

5 VLAN2

6 VLAN2

7 VLAN2

8 VLAN2

 

The settings required to achieve this:

 

Port1: Trunk, VLAN1

All other ports will be access, 2-4 will have VLAN1, 5-8 will have VLAN2.

 

Default VLAN group will be include 1-4, untagged

VLAN2 will include 5-8 untagged + 1 tagged.

 

Topic 2

 

Getting a Unifi Access point to work with the TP Link switch - discovering the necessary settings was harder.

 

The switch has wifis for default VLAN and VLAN5

 

Let's assume these physical connectins (on the switch):

Port 1: Uplink port to all networks

Port 2: Access Point connection

 

Most of my switches are older and there is not the graphical port selection screen, but just the list with checkboxes at the beginning of every line.

 

Those are the required settings:

Default VLAN including port 1, VLAN ID 1, port type trunk

VLAN5 including ports 1+2, only port 2 gets VLAN ID 5

 

Now the special thing here is the port type of port 2. From what I've been told most switch brands would require you to set this to trunk as well. But this will not work with the Unifi access point if its management network is on the default VLAN 1. Here you need to set port 2 to general and tagged.

See here for more details:

https://community.ui.com/questions/Cant-get-VLANs-working-on-Wifi-AC-Pro/3a37151d-9d98-4be0-a0cb-07c44477f661#answer/1c362bf1-8cc6-4314-a739-4bb8747406e9

 

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