My question is about the literal and precise meaning of the term "VLAN".
According to IEEE 802.1Q-2014, a LAN is a single segment of a medium. A cable connecting a PC to a switch port is a single LAN. I know that is not how we use the term, but that is how it is defined. What we call "the LAN" is defined as a Bridged Local Area Network. So, in practice, most LAN's when the term is correctly used have only one end station and one switch port on them nowadays.
So you would expect a Virtual LAN (or VLAN) to be a virtualisation of this. The IEEE standard does indeed define a "VLAN Bridged Network" as a Virtual Bridged Network, so what we call a "VLAN" e.g. VLAN 20 seems to be more accurately described as a VBN.
A VLAN itself is defined as "The closure of a set of Media Access Control (MAC) Service Access Points (MSAPs) such that a data request in one MSAP in the set is expected to result in a data indication in another MSAP in the set." Without a bridge, this would refer to a subset of stations on a LAN (single segment), although in practice we never implement this (that I know of).
Would anyone like to confirm or refute this?
Vlan – a VLAN (really)
bridgevlan
Best Answer
A VLAN is a layer 2 construct which separates devices into separate broadcast domains.
A VLAN is a group of devices on one or more LANs that are configured to communicate as if they were attached to the same wire, when in fact they are located on a number of different LAN segments. Because VLANs are based on logical instead of physical connections, they are extremely flexible.