3Com 3CRWDR300A-73, User Manual

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104 C
HAPTER
5: C
ONFIGURING THE
R
OUTER
VLAN A VLAN is a flexible group of devices that can be located anywhere in a
network, but they communicate as if they are on the same physical
segment. With VLANs, you can segment your network without being
restricted by physical connections - a drawback of traditional network
design. As an example, with VLANs you can segment your network
according to:
■
Departmental groups - For example, you can have one VLAN for the
Marketing department, another for the Finance department, and
another for the Development department.
■
Hierarchical groups - For example, you can have one VLAN for
directors, another for managers, and another for general staff.
■
Usage groups - For example, you can have one VLAN for users of
e-mail, and another for users of multimedia.
The main benefit of VLANs is that they provide a network segmentation
system that is far more flexible than any traditional network. Using VLANs
also provides you with three other benefits:
■
It eases the change and movement of devices on IP networks: With
traditional IP networks, network administrators spend much of their
time dealing with moves and changes. If users move to a different IP
subnet, the IP addresses of each end-station must be updated
manually.
With a VLAN setup, if an end-station in VLAN 1 is moved to a port in
another part of the network, you only need to specify that the new
port forwards VLAN 1 traffic.
■
It provides extra security: Devices within each VLAN can only
communicate directly with devices in the same VLAN. If a device in
VLAN 1 needs to communicate with devices in VLAN 2, the traffic
needs to pass through a routing device or Layer 3 switch.
■
It helps to control broadcast traffic: With traditional networks,
congestion can be caused by broadcast traffic that is directed to all
network devices whether they require it or not. VLANs increase the
efficiency of your network because each VLAN can be set up to
contain only those devices that need to communicate with each other.
The VLAN screen allows you to setup VLAN groups. Note that Wireless
LAN is permanently assigned to Default VLAN.