Over the years, there has been a lot of discussion on if VLAN 1 in Cisco switches is special or not. Does it have any characteristics that other VLANs don’t? I covered some of this in the Is VLAN 1
Encapsulation of PDUs On Trunk Ports
When I studied for my CCIE almost 15 years ago, I recall that I was fascinated by how different PDUs such as CDP, DTP, STP would have different encapsulations on a trunk depending on the configuration of it. What happens
Adding Arista Switch to CML
I wanted to add Arista switches to CML to do some STP interopability testing. However, the process of adding them is not well described. I had to refer to some Youtube videos to understand what to do. This is what
Detecting Mismatched Native VLANs
Many people have seen the message logged to their switch about a mismatched native VLAN on a trunk, but how is it detected? There are two methods of detecting mismatched native VLAN on a trunk link: To demonstrate how this
802.1Q-Tagged Frames Through Unmanaged Switch – Forwarded or Dropped?
As a follow-up to the post yesterday on native VLANs, there was a question on what would happen to 802.1Q-tagged frames traversing an unmanaged switch. Unmanaged in this case being a switch that does not support VLANs. While this might
Why Do We Have Native VLANs?
Recently, my friend Andy Lapteff asked an excellent question. Why do we have native VLANs? As in, why allow untagged frames on a trunk link? There was a time where we didn’t have VLANs. At first there was hubs, then