H3C S7500E Series Ethernet Switches Operation Manual

Operation Manual – VLAN
H3C S7500E Series Ethernet Switches Chapter 1 VLAN Configuration
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Chapter 1 VLAN Configuration
When configuring VLAN, go to these sections for information you are interested in:
z Introduction to VLAN
z Configuring Basic VLAN Attributes
z Configuring Basic VLAN Interface Attributes
z Configuring Port-Based VLAN
z Configuring Protocol-Based VLAN
z Configuring IP-Subnet-Based VLAN
z Displaying and Maintaining VLAN
z VLAN Configuration Example
1.1 Introduction to VLAN
1.1.1 VLAN Overview
Ethernet is a network technology based on the Carrier Sense Multiple Access/Collision
Detect (CSMA/CD) mechanism. As the medium is shared in an Ethernet, network
performance may degrade as the number of hosts on the network is increasing. If the
number of the hosts in the network reaches a certain level, problems caused by
collisions, broadcasts, and so on emerge, which may cause the network operating
improperly. In addition to the function that suppresses collisions (which can also be
achieved by interconnecting LANs), virtual LAN (virtual LAN) can also isolate broadcast
packets. VLAN divides a LAN into multiple logical LANs with each being a broadcast
domain. Hosts in the same VLAN can communicate with each other like in a LAN.
However, hosts from different VLANs cannot communicate directly. In this way,
broadcast packets are confined to a single VLAN, as illustrated in the following figure.
Figure 1-1 A VLAN diagram