Section 2.1.c Implement and Troubleshoot VLAN
We cannot discuss VLANs until we learn the dot1q tag in depth.
The dot1q header comes before the ethertype field in ethernet.
It is a 4 byte value used to denote these 3 fields:
802.1P (class of service/layer 2 qos)
DEI: Drop eligible indicator
ID: vlan membership