Virtual LAN (VLAN) on a Layer 2 switch offers some of the benefits of both
bridging and routing. Like a bridge, a VLAN switch forwards traffic based on the
Layer 2 header, which is fast. Like a router, it partitions the network into logical
segments, providing better administration, security, and management of multicast
traffic.

A VLAN is a set of end stations and the switch ports that connect them. You might
have many reasons for the logical division, such as department or project
membership. The only requirement is that the end station and the port to which it
is connected both belong to the same VLAN(s).

Each VLAN in a network has an associated VLAN ID, which appears in the IEEE
802.1Q tag, also known as VLAN tag, in the Layer 2 header of packets transmitted
on a VLAN. If an end station omits the tag, or the VLAN portion of the tag, the first
switch port to receive the packet either rejects it or inserts a tag matching its
default VLAN ID. A port can handle traffic for more than one VLAN, but it can only
support the Port VLAN ID (PVID).

The switch is pre-configured with VLAN ID 1 as the Default VLAN. All ports are
members of this VLAN, and use its VLAN ID (1) as their PVID.