Friday, January 16, 2015


Introduction of VLAN

          Vlan (Virtual Local Area Network) Foundation:-   Switch Vlan

Ø  Trunk Port :- That Carry All Vlan Traffic Between Your Switches

ü  Logically Groups Users
ü  Segments Broadcast Domain
ü  Subnet Correlation
ü  Access Control
ü  Quality Of Service

v  The Normal Switches World:-
Ø  1 Collision Domain Per Port
Ø  Broadcast Sent To All Ports
Ø  One Subnet Per Lan
Ø  Very Limited Access Control
The Flexibility Of Vlans:-

Ø   Segmentation Of Users Without Routers
Ø  No Longer Limited To Physical Location
Ø  Tighter Control Of Broadcast
 Understanding Trunks and VTP              
    • What is Trunking
    Ø Trunking(also known as Tagging) passes multi-Vlan information b/w switches
    Ø Places Vlan information into each frame
    Ø Layer 2 feature
    Ø Trunking is a Cisco term.

    •    Trunking Language : 802.1Q
    Ø Switches pass the information b/w each other using official languages 802.1Q that is industry standard
  •    Native Vlan:- is designed for packet that received on the trunk that are not tag
  • Double Edge word: VTP 
  • VLAN Trunking Protocol (VTP):-It Replicate the Vlans into Multiple Switches through Trunk Ports

The VTP Modes:-

Ø  Server(Default)
ü  Power to change vlan information
ü  Sends and receive vtp updates
ü  Saves vlan configuration

Ø  Client
ü  Cannot change vlan information
ü  Sends and receive vtp updates
ü  Does not save vlan configuration

Ø  Transparent
ü  Power to change vlan information
ü  Forward (pass through) vtp updates
ü  Does not listen to vtp advertisements
ü  Saves Vlan configuration

  Ø  Off (configurable only in CatOS switches):- in the VTP off mode, switches behave the same as in VTP transparent mode with the exception that VTP advertisements are not forwarded.

Vlan Pruning

Ø  Keeps unnecessary broadcast traffic from crossing trunk link.
Ø  Only work on VTP Server



  1. Please upload PDF of VLAN Introduction

    1. Dear Kindly refer to CCNP Switch option then Vlan and Trunking