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What is VLAN ? VLAN Overview

Hello Everyone, In this article I’ll discuss about VLAN. What is Vlans ? Vlan are Virtual Local Area Network.It is logical connections with other similar devices.

When we placing device into vlan network, they are have the following characterictics :

  • It provides segmentation of the various groups of devices on the same switch.
  • It provides organization that is more manageable :
    • Broadcast, Unicast and multicast are isolated in the individual vlan.
    • Each vlan will have the unique segment of network or unique range of ip address.
    • Smaller broadcast domains

Here’s some Types of VLANs :


Vlan network have default vlan on the vlan1. and on cisco devices vlan 1 are default vlan, default native vlan and default management vlan. And we need to remember that the vlan 1 cannot be deleted or renamed.



Vlan data is used for general traffic like web connection, email and etc. vlan data is on vlan 1 by default because for default nework on cisco all interfaces are assign on vlan1.



Native vlan is used on vlan trunking only. All frames are tagged on an 802.1Q trunk link except for those on native vlan.



Management vlan is used for remote connection like telnet or SSH and should not be carried with end user traffic. Typically that the vlan that is SVI (Switch Virtual Interfaces) for layer 2 switch.



The vlan is a separate vlan that is required for voice traffic. Because the voice traffic requires :

  • Assured Bandwidth
  • High QoS Priority
  • Ability to avoid congestion
  • Delay connection less that 150ms from source to destination



What is vlan trunks ? a trunks is a point to point link between two devices. Usually is switches devices.  Trunk is have some functions :

  • Allow more than one VLAN
  • Extend the vlan across the entire network
  • By Default it support All Vlans, in some case we can limit some vlan that are allowed to forward to the trunk links.
  • Support 802.1Q trunking


The Following is diffrent network without vlans and network with vlans :

  • Network without vlans, as the following we can see network on PC1 will be broadcast on all available ports on local switching.


  • And we can see the different on network with vlans, network on PC1 will be broadcast on Vlan 10 Ports.



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