MAC address ranges of virtualized world

Nowadays when several MAC addresses are associated with one switch port, we cannot assume that this port is connected to another switch or hub as before. It might be connected to a Virtual Machine server.

Wi-Fi Blocking Paint

We know that Wireless LAN (Wi-Fi) is riding on non-licensed bands of radio frequencies. It is unavoidable, especially in a metropolitan area, that our facilities are filled with un-wanted wireless LAN radios.

With new strong encryption, we do not have to worry about the information leakage. However, we DO have to worry about effective transmission throughput. The more users in the same channels, the less effective throughput can we get!

How to verify the Secondary Root?

As you know  we can configure the designated switch as the "Primary root role" or the "Secondary root role" using the following commands:

spanning-tree vlan 10 root primay
spanning-tree vlan 20 root secondary
  

Although these commands are just "macros" that we cannot see them in the running configuration, it is still easy to verify the "Primary root role" is correctly configured: We just use "show spanning-tree" command to check the designated switch is really the current "Root Bridge".