Vlan Configuration; Introduction To Vlan; Vlan Overview - 3Com MSR 50 Series Configuration Manual

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Introduction to VLAN

VLAN Overview

VLAN C
ONFIGURATION
When configuring VLAN, go to these sections for information you are interested
in:
"Introduction to VLAN" on page 487
■
"Configuring Basic VLAN Attributes" on page 489
■
"Configuring VLAN Interface Basic Attributes" on page 490
■
"Configuring a Port-Based VLAN" on page 491
■
"Displaying and Maintaining VLAN" on page 494
■
"VLAN Configuration Examples" on page 495
■
Ethernet is a network technique based on CSMA/CD (carrier sense multiple
access/collision detect) mechanism. As the medium is shared in an Ethernet,
network performance degrades with the increasing of the number of the hosts in
the network. 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. Although switch prevents collisions between
LANs, it still cannot block broadcast packets. VLAN, however, divides a LAN into
multiple logical LANs, with each being a broadcast domain. Hosts in the same
VLAN can communicate with each other just like in a LAN, and hosts from
different VLANs cannot communicate directly. In this way, broadcast packets are
confined in VLANs, as illustrated in the following figure.
Figure 137 A VLAN diagram
VLAN 2
Router
VLAN 5
VLAN 2
Switch A Switch B
VLAN 5