Basics of VLAN & VTP

VLAN

Virtual Local Area Network

A VLAN is a logical grouping or networking of hosts connected to a defined port of a switch. When you create VLAN, you can create smaller broadcast domains within Layer 2 switch. Each VLAN creates its own broadcast domain.

USE CASES:

Wide Area Network(WAN) domain: 

Here what we do, we logically divide the switch in to smaller broadcast domain to enabling adding many sub nets.

• IP Telephones, Video Conferencing system in a WAN environment at different department, building, branch offices, etc.

Broadcast Domain:

It is a logical division where all nodes reach at each node by broadcasting.

This VLAN can be two types, Static and Dynamic

• A static VLAN is just assign one switch port to a VLAN. They are most secure.
• A dynamic VLAN is just anytime you plug or connect a host to the switch. 

Sample VLAN Connectivity

Let say,

There are different departments in different color. There are two branch offices of one organization. The Yellow department is common for both branches (let say logistics or IT). That Yellow one of both branches were created as VLANs under switch S1 and S2 to communicate under Router R.

The S1 and S2 are connected through a TRUNK link. Yellow will communicate with only Yellow. 

Got?

VTP

VLAN Trunking Protocol

The Basic need of VTP is to manage all VLAN configurations across the network and maintain consistency.

In brief;

• It allows to add, delete and rename VLANs.
• It helps in tracking and monitoring of VLANs.
• Adding VLANs using easy plug and play.

For the operation of VTP, there is default VTP server in Cisco switches. 

-DR