Comments on: Virtual Local Area Networks (VLANs)

By: mustafa

mustafa — Sun, 03 May 2026 21:18:55 +0000

what that, three days with IA to understand these and only one hour here to understand all. thanks man

By: Ujjwal

Ujjwal — Wed, 21 Jan 2026 17:23:57 +0000

in the question, the SwT and SwV are connected using Trunk port and have different native vlan 7 and 5, won’t it give mismatch error during the configuration.

By: Rishita

Rishita — Wed, 07 May 2025 14:10:57 +0000

In reply to Ed Harmoush. But How come the Data coming to Vlan 3 - tagged as Vlan 3 is getting forwarded via Vlan 7 Native trunk link .. That too tagged .. isn't Native Vlan suppose to send untagged data only.

By: Mukesh

Mukesh — Mon, 17 Feb 2025 06:45:56 +0000

Hi Ed,

Can you do a session on PVLAN?

Thanks,
Mukesh

By: Crypto Blog

Crypto Blog — Mon, 17 Feb 2025 05:40:24 +0000

So glad to see that information in this blog. Thanks for making this awesome website!

By: Ivan

Ivan — Thu, 14 Nov 2024 07:33:12 +0000

Hi Ed!

Thank you for this wonderful post. I’m a seasoned IT person and it took me so much pain and effort to get the concept of VLANs when I started out in IT more than a decade ago. This is so much easier for newbies nowadays.

There is also a concept of asymmetric VLANs where egress traffic from multiple VLANs are allowed to a certain destination VLAN, but the reply (ingress) traffic only comes back to the VLAN where this traffic initially originated from. Not sure if such thing exists in a Cisco world.

By: Aleksandrs

Aleksandrs — Thu, 22 Aug 2024 14:26:03 +0000

In reply to Aleksandrs. I came across a concept known as "Router on a Stick," which aligns perfectly with your illustration. In essence, the router sends packets tagged with a specific VLAN identifier based on the target IP address.

By: Aleksandrs

Aleksandrs — Thu, 22 Aug 2024 13:50:43 +0000

Hi Ed!
I watch your courses frequently, share them with my colleagues and using those when teaching myself.
I am now looking through your VLAN course again in the Tagged Ports and Untagged Ports section where you explain trunk ports.I don’t understands how router is seeing trunk ports. How router understands that it needs to send the data to the same physical port? – Does trunk port has one MAC address for each VLAN or additional router port configuration is required? In your illustration router is changing tag on a packet it looks like router configuration for VLANs is required to work. As you can see, I really am confused about the VLANs entering router part.

By: Rob

Rob — Wed, 17 Jul 2024 21:11:43 +0000

Thanks for fine article. BUT what if one or more hosts CAN “understand” VLANs? My PCs each have a NIC which can optionally be configured with one (and only one) VLAN ID. Now what happens? Does it send out all packets with that tag added, and if so, what does the switch port do if configured for the same VLAN ID? Or, if the switch port is (?mis-)configured with NO VLAN ID? I assume that if the host NIC receives a frame with its configured VLAN ID, it strips off the tag and processes it normally within the host. Correct?

By: Fred

Fred — Fri, 28 Jun 2024 08:03:51 +0000

This was a fantastic article. I highly recommend doing the exercise.
Put the answers on side panel and the picture on another.

Thank you,
Fred.