In an organisation or a particular network, there are reasons why certain hosts access each other while others do not. As an example, members of the accounting department may be the only users who need to access the accounting server. This is where segmenting your network with VLANs comes in. A Virtual Local Area Networks (VLAN) is a logical broadcast domain that can span multiple physical LAN segments. With VLANs, you can group together stations by logical function, by project teams, or by applications, despite the physical location of the users.
Lets take for an example of an organisation in the same building with different departments, the marketing, accounts and IT departments.
In a normal switched network, every host connected to the network is able to access the other user’s data on the network.
With a proper VLAN configured, it was decided that only the accounting department can access the accounting sever and IT department can access the marketing department. The departments are now logically separated into two virtual LANs.
By Using this logical grouping or VLANs, the accounting department is grouped on the same VLANs with the server, even though IT, accounting and marketing are physically located within the same building.
Each VLAN functions as a separate LAN. A VLAN can be implemented on one or more switches; users on different VLANs behave as if they were on the same network segment. A device can be assigned to a VLAN based on its location, MAC address, IP address, or the applications that the device most frequently uses.
A VLAN has two major functions:
i. Contains broadcasts.
ii. Groups devices. Devices located on one VLAN are not visible to devices located on another VLAN.
Devices or users connected to a VLAN can only communicate with other users in the same VLAN despite whether those devices or users are on the same switch or different switches. VLANs can be used to isolate certain traffic for security reasons; VLANs conserve bandwidth, and concentrate traffic on an organisations network. All of these features combine to improve network performance.
Note:
For devices on the same VLANS to communicate requires unique logical address and a Layer 3 device. And switches have to be configured with trunk links between them.
Author: Chika Nwokeoma
Article Source: EzineArticles.com
Provided by: Excise Tax
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