3.1 Introduction to VLAN
This section describes definition, purpose and benefits of VLAN.
Definition
The Virtual Local Area Network (VLAN) technology divides a physical LAN into multiple
broadcast domains, each of which is called a VLAN. Hosts within a VLAN can communicate
with each other, while hosts in different VLANs cannot directly communicate with each other.
Therefore, the broadcast packets are limited in each VLAN.
Purpose
The Ethernet technology is used to share communication media and data based on the Carrier
Sense Multiple Access/Collision Detection (CSMA/CD). If there are a large number of hosts on
an Ethernet network, collision becomes a serious problem and can lead to broadcast storms. As
a result, network performance deteriorates. Switches can be used to connect LANs, preventing
collision. However, broadcast packets cannot be isolated and network quality cannot be
improved.
The VLAN technology divides a physical LAN into multiple broadcast domains, each of which
is called a VLAN. Hosts within a VLAN can communicate with each other, while hosts in
different VLANs cannot communicate with each other directly. Therefore, the broadcast packets
are limited in each VLAN.
NOTE
In this document, the Layer 2 switch is referred to as the switch for short.
Figure 3-1
Networking diagram for a typical VLAN application
VLAN-A
VLAN-B
VLAN-C
Router
Switch1
Switch2
Switch3
Huawei AR530&AR550 Series Industrial Switch Routers
Configuration Guide - Ethernet Switching
3 VLAN Configuration
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